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Gemini 1

Gemini 1 was the first mission in NASA's Gemini program. An uncrewed test flight of the Gemini spacecraft, its main objectives were to test the structural integrity of the new spacecraft and modified Titan II launch vehicle. It was also the first test of the new tracking and communication systems for the Gemini program and provided training for the ground support crews for the first crewed missions.

Originally scheduled for launch in December 1963, difficulties in the development of both the spacecraft and its booster caused four months of delay. Gemini 1 was launched from Launch Complex 19 at Cape Kennedy (now Canaveral), Florida on April 8, 1964. The spacecraft stayed attached to the second stage of the rocket. The mission lasted for three orbits while test data were taken, but the spacecraft stayed in space for almost 64 orbits until its orbit decayed due to atmospheric drag. The spacecraft was not intended to be recovered, and holes were drilled through its heat shield to ensure it would not survive re-entry.

Background
Project Gemini was conceived as a bridge between America's single-seat Project Mercury and the three-seat Project Apollo. With a design largely extrapolated from its predecessor, the Gemini spacecraft would allow two astronauts to conduct the maneuvers inherent in Apollo's lunar mission: rendezvous, docking, and changing of orbit. Moreover, Gemini would support astronauts in space for extended flights, approximating the expected length of the Apollo missions.

Its two-person capacity and greater capabilities meant that Gemini would be a substantially heavier spacecraft than Mercury had been — too heavy to be lofted into orbit by Mercury's Atlas rocket. A replacement was needed. The newly developed Titan II ICBM (which had also been tapped by the Air Force for its X-20 spaceplane project) was an attractive replacement. It had a thrust some two and a half times that of the Atlas, a far simpler mechanical construction, and the ability to store propellants indefinitely. Moreover, the Titan II's propellants mixed less violently than those of Atlas meaning a booster explosion, should it happen, would be less violent. This made obsolete the heavy escape tower used in the Mercury program; instead, ejection seats could be used.

The primary goal of the first Gemini mission was to flight test the modified Titan II launch vehicle and the basic structural soundness of the Gemini capsule under launch and orbital conditions. Consequently, the first Gemini capsule could be a largely boilerplate structure. Secondary goals of the mission included testing the remote guidance systems, the Titan's redundancy systems, and evaluation of the Gemini-Titan malfunction detection system.

Pre-flight
Gemini Spacecraft Number 1 was built specifically for the uncrewed mission. Most internal systems were replaced with dummies and ballast approximating the weight and balance of the crewed spacecraft. In place of the crew couches, two pallets of instruments were installed for the relaying via telemetry of the pressure, vibration, acceleration, temperature, and structural loads experienced during the short flight. A spacecraft heat shield was installed, but four large holes were drilled in it to ensure Gemini 1 was destroyed during reentry.

Even with the simplified systems, this first Gemini encountered several weeks of delay in testing. Nevertheless, it was not the spacecraft that caused the launch date, originally planned for December 1963, to slip. Rather, it was the testing and man-rating of the Titan II launch vehicle. Assembled on May 21, 1963, the first Titan-Gemini launch vehicle required comprehensive testing and retesting, and it was not until October that it was ready for transport to the launch site — where considerable preparation still had to be done. Moreover, there was concern that the Titan II produced too much vertical oscillation (pogo) to be usable at all, and consideration was given to using the Saturn I rocket instead, at least for the first missions. However, on November 1, 1963, the Air Force flew a Titan II rocket with standpipes in its oxidizer lines and mechanical accumulators in its fuel lines, which suppressed the pogo effect.

Inefficient project management threatened to further delay the first Gemini launch, which by November had already been pushed back to February 28, 1964. Gemini Manager Charles Mathews united the several disparate teams into a single Gemini Launch Vehicle Coordination Committee with clearly defined management and communication channels. This measure ensured that no more time would be lost due to uncertain authority, duplicated effort, or conflicting decisions. Still, issues that arose during testing caused the launch date to slip further. The Titan II booster was not ready for final readiness testing until March 3, 1964, the same day that Gemini Spacecraft Number 1 arrived at the launch complex for mating with its booster. Faulty test equipment caused a further delay of two weeks. By late March, all serious hurdles cleared, Gemini 1's launch date was set for April 7. The resolution of a failure in the secondary autopilot caused one last day of delay. Finally, by noon of the seventh, Gemini 1's Mission Review Board determined unanimously that all systems were cleared for flight.

Mission and results
After a flawless countdown, Gemini 1's Titan II booster lifted off from Cape Kennedy's (now Canaveral) Launch Complex 19 at 11:00:01 EDT, April 8, 1964. The first stage was jettisoned after two and a half minutes with the rocket 64 km high and 91 km downrange. At that moment, there was an unexpected three-second loss of signal from the craft. It was later determined that this brief communications blackout was caused by charged ions from the separation and startup of the second stage, similar to the blackout during spacecraft reentry. All subsequent Gemini flights would have the same brief blackout.

The spacecraft achieved orbit five and a half minutes after launch. The launch vehicle had imparted an excess 7 meters (24 feet) per second of velocity to the Gemini 1, placing the spacecraft into an orbit with an apogee of 320 km instead of the planned 299 km. This lengthened Gemini 1's lifespan from the planned three and a half days to four.

The formal mission of Gemini 1 was over long before that. Its battery had only been designed to last a single orbit, and only the first three orbits — lasting four hours and 50 minutes — were part of the flight plan. Gemini 1 and its attached second stage were tracked by the Manned Space Flight Network until they reentered over the South Atlantic, midway between South America and Africa, on April 12, 1964, during their 64th orbit.

As a result of the successful flight, the Titan II was considered "man-rated" (safe for use in human spaceflight). Man-rating the Gemini capsule itself would not be accomplished until the launch of Gemini 2 nine months later, on January 19, 1965.

The Gemini 1 mission was supported by 5,176 United States Department of Defense personnel, as well as eleven aircraft and three ships provided by the Department of Defense.

title: Gemini 1


text:
Jordan, Hong Kong

Jordan is an area in Hong Kong, located on Kowloon Peninsula. It is named after a road of the same name in the district. The area is bordered by King's Park to the east, Tsim Sha Tsui to the south, Ferry Point to the west, and Yau Ma Tei to the north. Administratively, it is part of Yau Tsim Mong District.

Geography
Jordan is located in the central part of the Yau Tsim Mong District. The western portion is officially known as Kwun Chung (官涌), especially before the MTR metro system went into service in 1979.

Jordan is considered as an area surrounded by Cox's Road to the east, Austin Road to the south, Ferry Street to the west, and Kansu Street to the north. This would make Jordan approximately 1 km2 in size with a population of about 150,000.

Like most of southern Kowloon, Jordan is entirely developed and urbanised other than a few small parks. Motor and pedestrian traffic throughout most of the day is very dense.

Character
Jordan is a microcosm of working-class Hong Kong. Like nearby districts of Mong Kok and Tsim Sha Tsui, large sections of Jordan hosts a mix of older residential high-rises, office buildings, street markets, hotels, eateries and an almost infinite variety of small shops. There are also sections offering karaoke, hostess bars and massage parlours; nearby Mong Kok is better known for such services, however.

Although Jordan lacks the sights and comforts to support mass mainstream tourism, it still attracts a small cadre of adventurous tourists interested in experiencing authentic working-class life in Hong Kong. For locals, many live in Jordan for its relatively affordable housing, its centralised location on the spine of Hong Kong's transportation network and its diverse cultural flavour.

Jordan is home to a large number of Indians, Pakistanis, Nepalese and other ethnic minorities. The area bordering Ferry Point therefore hosts a wide array of South Asian and other restaurants and market stores.

History
On 23 January 2021, HKSAR government imposed the first COVID-19 lockdown in Jordan at 04:00. The lockdown area reopened at 03:30 on 25 January, lasting for 23.5 hours.

Tourism and recreation
The following noteworthy places are located in Jordan:

 * Australia Dairy Company
 * Diocesan Girls' School
 * Gun Club Hill Barracks
 * Jade Market & Jade Street
 * Kowloon Union Church
 * Man Wah Sun Chuen
 * Temple Street Night Market
 * King George V Memorial Park, Kowloon
 * Kowloon Cricket Club
 * Kowloon Park (North Entrance)

Jordan is also home to a number of prominent hotels in Kowloon:
 * Novotel Nathan Road Kowloon Hong Kong
 * Eaton Hotel Hong Kong
 * Nathan Hotel
 * Mayfair Garden Hotel

Major roads and streets

 * Austin Road
 * Battery Street
 * Bowring Street
 * Gascoigne Road
 * Cox's Road
 * Jordan Path
 * Jordan Road
 * Kansu Street
 * Kwun Chung Street
 * Min Street
 * Nanking Street
 * Ning Po Street
 * Pak Hoi Street
 * Parkes Street, named after Harry Parkes
 * Pilkem Street
 * Reclamation Street
 * Saigon Street
 * Temple Street
 * Woosung Street

Transport
Nathan Road and Jordan Road run through the area. The intersection of these two roads is a major intersection in Kowloon.

Jordan is served by the MTR station of the same name, on the Tsuen Wan line, as well as numerous bus lines.

Jordan is also the site of a bus terminal for transport to the Huanggang Border Crossing in Shenzhen, China.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Jordan, Hong Kong


text:
Aldosterone

Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a central role in the homeostatic regulation of blood pressure, plasma sodium (Na+), and potassium (K+) levels. It does so primarily by acting on the mineralocorticoid receptors in the distal tubules and collecting ducts of the nephron. It influences the reabsorption of sodium and excretion of potassium (from and into the tubular fluids, respectively) of the kidney, thereby indirectly influencing water retention or loss, blood pressure, and blood volume. When dysregulated, aldosterone is pathogenic and contributes to the development and progression of cardiovascular and kidney disease. Aldosterone has exactly the opposite function of the atrial natriuretic hormone secreted by the heart.

Aldosterone is part of the renin–angiotensin–aldosterone system. It has a plasma half-life of less than 20 minutes. Drugs that interfere with the secretion or action of aldosterone are in use as antihypertensives, like lisinopril, which lowers blood pressure by blocking the angiotensin-converting enzyme (ACE), leading to lower aldosterone secretion. The net effect of these drugs is to reduce sodium and water retention but increase the retention of potassium. In other words, these drugs stimulate the excretion of sodium and water in urine, while they block the excretion of potassium.

Another example is spironolactone, a potassium-sparing diuretic of the steroidal spirolactone group, which interferes with the aldosterone receptor (among others) leading to lower blood pressure by the mechanism described above.

Aldosterone was first isolated by Sylvia Tait (Simpson) and Jim Tait in 1953; in collaboration with Tadeusz Reichstein.

Biosynthesis
The corticosteroids are synthesized from cholesterol within the zona glomerulosa and zona fasciculata of adrenal cortex. Most steroidogenic reactions are catalysed by enzymes of the cytochrome P450 family. They are located within the mitochondria and require adrenodoxin as a cofactor (except 21-hydroxylase and 17α-hydroxylase).

Aldosterone and corticosterone share the first part of their biosynthetic pathways. The last parts are mediated either by the aldosterone synthase (for aldosterone) or by the 11β-hydroxylase (for corticosterone). These enzymes are nearly identical (they share 11β-hydroxylation and 18-hydroxylation functions), but aldosterone synthase is also able to perform an 18-oxidation. Moreover, aldosterone synthase is found within the zona glomerulosa at the outer edge of the adrenal cortex; 11β-hydroxylase is found in the zona glomerulosa and zona fasciculata.

Aldosterone synthase is normally absent in other sections of the adrenal gland.

Stimulation
Aldosterone synthesis is stimulated by several factors:
 * increase in the plasma concentration of angiotensin III, a metabolite of angiotensin II
 * increase in plasma angiotensin II, ACTH, or potassium levels, which are present in proportion to plasma sodium deficiencies. (The increased potassium level works to regulate aldosterone synthesis by depolarizing the cells in the zona glomerulosa, which opens the voltage-dependent calcium channels.) The level of angiotensin II is regulated by angiotensin I, which is in turn regulated by renin, a hormone secreted in the kidneys.
 * Serum potassium concentrations are the most potent stimulator of aldosterone secretion.
 * the ACTH stimulation test, which is sometimes used to stimulate the production of aldosterone along with cortisol to determine whether primary or secondary adrenal insufficiency is present. However, ACTH has only a minor role in regulating aldosterone production; with hypopituitarism there is no atrophy of the zona glomerulosa.
 * plasma acidosis
 * the stretch receptors located in the atria of the heart. If decreased blood pressure is detected, the adrenal gland is stimulated by these stretch receptors to release aldosterone, which increases sodium reabsorption from the urine, sweat, and the gut. This causes increased osmolarity in the extracellular fluid, which will eventually return blood pressure toward normal.
 * adrenoglomerulotropin, a lipid factor, obtained from pineal extracts. It selectively stimulates secretion of aldosterone.

The secretion of aldosterone has a diurnal rhythm.

Biological function
Aldosterone is the primary of several endogenous members of the class of mineralocorticoids in humans. Deoxycorticosterone is another important member of this class. Aldosterone tends to promote Na+ and water retention, and lower plasma K+ concentration by the following mechanisms:

 * 1) Acting on the nuclear mineralocorticoid receptors (MR) within the principal cells of the distal tubule and the collecting duct of the kidney nephron, it upregulates and activates the basolateral Na+/K+ pumps, which pumps three sodium ions out of the cell, into the interstitial fluid and two potassium ions into the cell from the interstitial fluid. This creates a concentration gradient which results in reabsorption of sodium (Na+) ions and water (which follows sodium) into the blood, and secreting potassium (K+) ions into the urine (lumen of collecting duct).
 * 2) Aldosterone upregulates epithelial sodium channels (ENaCs) in the collecting duct and the colon, increasing apical membrane permeability for Na+ and thus absorption.
 * 3) Cl− is reabsorbed in conjunction with sodium cations to maintain the system's electrochemical balance.
 * 4) Aldosterone stimulates the secretion of K+ into the tubular lumen.
 * 5) Aldosterone stimulates Na+ and water reabsorption from the gut, salivary and sweat glands in exchange for K+.
 * 6) Aldosterone stimulates secretion of H+ via the H+/ATPase in the intercalated cells of the cortical collecting tubules
 * 7) Aldosterone upregulates expression of NCC in the distal convoluted tubule chronically and its activity acutely.

Aldosterone is responsible for the reabsorption of about 2% of filtered sodium in the kidneys, which is nearly equal to the entire sodium content in human blood under normal glomerular filtration rates.

Aldosterone, probably acting through mineralocorticoid receptors, may positively influence neurogenesis in the dentate gyrus.

Mineralocorticoid receptors
Steroid receptors are intracellular. The aldosterone mineralocorticoid receptor (MR) complex binds on the DNA to specific hormone response element, which leads to gene specific transcription. Some of the transcribed genes are crucial for transepithelial sodium transport, including the three subunits of the epithelial sodium channel (ENaC), the Na+/K+ pumps and their regulatory proteins serum and glucocorticoid-induced kinase, and channel-inducing factor, respectively.

The MR is stimulated by both aldosterone and cortisol, but a mechanism protects the body from excess aldosterone receptor stimulation by glucocorticoids (such as cortisol), which happen to be present at much higher concentrations than mineralocorticoids in the healthy individual. The mechanism consists of an enzyme called 11 β-hydroxysteroid dehydrogenase (11β-HSD). This enzyme co-localizes with intracellular adrenal steroid receptors and converts cortisol into cortisone, a relatively inactive metabolite with little affinity for the MR. Liquorice, which contains glycyrrhetinic acid, can inhibit 11β-HSD and lead to a mineralocorticoid excess syndrome.

The role of the renin–angiotensin system
Angiotensin is involved in regulating aldosterone and is the core regulation. Angiotensin II acts synergistically with potassium, and the potassium feedback is virtually inoperative when no angiotensin II is present. A small portion of the regulation resulting from angiotensin II must take place indirectly from decreased blood flow through the liver due to constriction of capillaries. When the blood flow decreases so does the destruction of aldosterone by liver enzymes.

Although sustained production of aldosterone requires persistent calcium entry through low-voltage-activated Ca2+ channels, isolated zona glomerulosa cells are considered nonexcitable, with recorded membrane voltages that are too hyperpolarized to permit Ca2+ channels entry. However, mouse zona glomerulosa cells within adrenal slices spontaneously generate membrane potential oscillations of low periodicity; this innate electrical excitability of zona glomerulosa cells provides a platform for the production of a recurrent Ca2+ channels signal that can be controlled by angiotensin II and extracellular potassium, the 2 major regulators of aldosterone production. Voltage-gated Ca2+ channels have been detected in the zona glomerulosa of the human adrenal, which suggests that Ca2+ channel blockers may directly influence the adrenocortical biosynthesis of aldosterone in vivo.

The plasma concentration of potassium
The amount of plasma renin secreted is an indirect function of the serum potassium as probably determined by sensors in the carotid artery.

Adrenocorticotropic hormone
Adrenocorticotropic hormone (ACTH), a pituitary peptide, also has some stimulating effect on aldosterone, probably by stimulating the formation of deoxycorticosterone, a precursor of aldosterone. Aldosterone is increased by blood loss, pregnancy, and possibly by further circumstances such as physical exertion, endotoxin shock, and burns.

The role of sympathetic nerves
The aldosterone production is also affected to one extent or another by nervous control, which integrates the inverse of carotid artery pressure, pain, posture, and probably emotion (anxiety, fear, and hostility) (including surgical stress). Anxiety increases aldosterone, which must have evolved because of the time delay involved in migration of aldosterone into the cell nucleus. Thus, there is an advantage to an animal's anticipating a future need from interaction with a predator, since too high a serum content of potassium has very adverse effects on nervous transmission.

The role of baroreceptors
Pressure-sensitive baroreceptors are found in the vessel walls of nearly all large arteries in the thorax and neck, but are particularly plentiful in the sinuses of the carotid arteries and in the arch of the aorta. These specialized receptors are sensitive to changes in mean arterial pressure. An increase in sensed pressure results in an increased rate of firing by the baroreceptors and a negative feedback response, lowering systemic arterial pressure. Aldosterone release causes sodium and water retention, which causes increased blood volume, and a subsequent increase in blood pressure, which is sensed by the baroreceptors. To maintain normal homeostasis these receptors also detect low blood pressure or low blood volume, causing aldosterone to be released. This results in sodium retention in the kidney, leading to water retention and increased blood volume.

The plasma concentration of sodium
Aldosterone levels vary as an inverse function of sodium intake as sensed via osmotic pressure. The slope of the response of aldosterone to serum potassium is almost independent of sodium intake. Aldosterone is increased at low sodium intakes, but the rate of increase of plasma aldosterone as potassium rises in the serum is not much lower at high sodium intakes than it is at low. Thus, potassium is strongly regulated at all sodium intakes by aldosterone when the supply of potassium is adequate, which it usually is in "primitive" diets.

Aldosterone feedback
Feedback by aldosterone concentration itself is of a nonmorphological character (that is, other than changes in the cells' number or structure) and is poor, so the electrolyte feedbacks predominate, short term.

Associated clinical conditions
Hyperaldosteronism is abnormally increased levels of aldosterone, while hypoaldosteronism is abnormally decreased levels of aldosterone.

A measurement of aldosterone in blood may be termed a plasma aldosterone concentration (PAC), which may be compared to plasma renin activity (PRA) as an aldosterone-to-renin ratio.

Hyperaldosteronism
Primary aldosteronism, also known as primary hyperaldosteronism, is characterized by the overproduction of aldosterone by the adrenal glands, when not a result of excessive renin secretion. It leads to arterial hypertension (high blood pressure) associated with hypokalemia, usually a diagnostic clue. Secondary hyperaldosteronism, on the other hand, is due to overactivity of the renin–angiotensin system.

Conn's syndrome is primary hyperaldosteronism caused by an aldosterone-producing adenoma.

Depending on cause and other factors, hyperaldosteronism can be treated by surgery and/or medically, such as by aldosterone antagonists.

The ratio of renin to aldosterone is an effective screening test to screen for primary hyperaldosteronism related to adrenal adenomas. It is the most sensitive serum blood test to differentiate primary from secondary causes of hyperaldosteronism. Blood obtained when the patient has been standing for more than 2 hours are more sensitive than those from when the patient is lying down. Before the test, individuals should not restrict salt and low potassium should be corrected before the test because it can suppress aldosterone secretion.

Hypoaldosteronism
An ACTH stimulation test for aldosterone can help in determining the cause of hypoaldosteronism, with a low aldosterone response indicating a primary hypoaldosteronism of the adrenals, while a large response indicating a secondary hypoaldosteronism. The most common cause of this condition (and related symptoms) is Addison's disease; it is typically treated by fludrocortisone, which has a much longer persistence (1 day) in the bloodstream.

title: Aldosterone


text:
Talk:Galilean transformation

Invariance
I have a serious question. Can anyone work out for me how Maxwell's equations (differential forms, of course) are not Galilean invariant, but are Lorentz invariant? I attempted the problem before but couldn't see anything conclusive in the math. Every book I've run across says "it's easy to show...." ub3rm4th 19:49, 30 Dec 2004 (UTC)

 * The fact that all electromagnetic waves propagate at the speed of light is enough to show they're not Galilean covariant. As for Lorentz covariance, see Faraday tensor. Phys 17:23, 18 Jan 2005 (UTC)

 * in the language of differential forms, Maxwell's equations are dF=0 and *d*F=j. The first is invariant under all diffeomorphisms of spacetime.  The second is only invariant under transformations which preserve the metric.  Lorentz transformations preserve the metric but Galilean transformations do not.  Just check what happens to the Hodge star in a Galilean boosted frame. -Lethe | Talk 17:07, Apr 24, 2005 (UTC)

 * Actually, the latter is invariant under all conformal transformations. Phys 01:08, 13 November 2005 (UTC)

 * Maybe any transformations which preserve the volume form as well? I forget, but it sounds plausible...  -Lethe | Talk 01:21, 13 November 2005 (UTC)

 * The "macroscopic" Maxwell equations (div D = rho, curl H - dD/dt = J, div B = 0, curl E + dB/dt = 0) have an invariance group containing GL(4) (as well as a superset of the conformal group), since they can be expressed in the language of differential forms. Their invariance, therefore, is independent of the distinction between Galilean versus Poincare (versus Euclidean, even!)

 * The distinction arises from the constitutive laws. The Lorentz relations (D = epsilon_0 E, B = mu_0 H) are Lorentz invariant. That's directly tied to the duality operation F -> *F, which both requires a metric to be defined, and effectively defines a metric. When the Maxwell field is regarded also as a special case of a gauge field, the duality also involves the metric associated with the gauge group. Here, the role of the gauge group metric and its dual is played respectively by (epsilon_0 c) and (mu_0 c).

 * In contrast, the older Maxwell relations, which are equivalent to (D = epsilon_0 (E + G x B), B = mu_0 (H - G x D)), would be Galilean covariant, with G transforming as G -> G + v under a boost by velocity v. Maxwell's G was removed by the time of Lorentz once its non-observation became apparent. This is why you see a gap in Maxwell's alphabet soup A, B, C, D, E, F, H, I, J.

 * The invariance of the macroscopic equations is a "superset" of the conformal group because it also includes a residue of the complexion transformation: D -> D + kB, H -> H - kE, E -> E, B -> B. Consequently, it's best to distinguish the field (D,H) from the dual *F. The fields that come out of the Heisenberg-Euler Lagrangian in effective field theory, for instance, embody a transformation by a non-zero k, as well as having a variable epsilon.

This article is terribly written
The English in this article is terrible - example:

"From the point of view of group theory, Einstein's special theory of relativity the Lorentz transformation group events, it is essentially a particle do uniform motion of the Lorentz transformation group - This is the core of Einstein's special theory of relativity all."

I'm not an expert in this field so don't feel comfortable editing it, but that sentence is embarrassing.

 * What is worse: the article contains absolute nonsense. JocK (talk) 21:31, 4 January 2008 (UTC)

 * Have made a start with a thorough clean-up. JocK (talk) 21:57, 4 January 2008 (UTC)

Do we have t' = t when v = 0?
Let me arrange two inertial systems first. One with observer Mr. A holding his clock A at the origin point O of the stationary system S and the other one with observer Mr. B holding his clock B at the origin point O’ of the moving system S’ and x axes is on the same line of x’ axes while system S’ is moving at a constant speed v toward the positive direction of x axes. The y axes is parallel to the y’ axes and so does z axes to z’ axes. Clocks A and B are identical and set to 0 when O’ = O.

1. Postulate

The main purpose of Galilean Transformation, GT, is to study the result of measurements for location and time when an event is measured by Mr. A and Mr. B. The time formula t' = t is a postulate when GT started.

2. Believed

However, if we let v = 0, then the time formulas in Lorentz Transformation, LT, and Special Theory of Relativity, STR, all become t’ = t. Even scientists cannot let LT and STR coexist, most of them believe that one of LT and STR must be correct. Since both LT and STR indicate if v = 0 then t' = t it is fair to say that most scientists believe in that "If v = 0, then GT is correct." But how do we prove that if v = 0 then t’ = t?

3. Investigation

Let me describe an experiment just finished this morning for your reference. The system S’ stopped when Mr. B was about 900 meters away from Mr. A this morning and Mr. B threw an orange into the air then caught it 2 seconds later. Mr. B could use his clock B to record the beginning and ending time of that event. At that time, how did Mr. A measure the t’ for that same event? Do we have t’ = t for that event? My answer is no.

4. t' = t is not correct

Since that event was 900 meters away from Mr. A when it started, we know that the picture of the moment the orange was leaving Mr. B’s hand would take some time to arrive Mr. A’s eyes. (900 meters) / (300000000 (meters/second)) = 3000 nanoseconds. That means if Mr. B recorded the beginning of that event as 5 minutes according to the clock B then Mr. A would record the beginning of that same event as 5 minutes and 3000 nanoseconds according to the clock A. If we assume that both clocks are able to read nanoseconds then we already proved that t’ = t is not true when v = 0.

5. Nanosecond Formula

To an observer at point o, an event starts ta at point a is recorded as it is started t’a = ta+(ao/c) so that t’a is always later than ta by the difference of the time that photons spend in traveling the distance ao from point a to point o. If the event ends tb at point b, then the time period of that event tab = tb-ta is recorded as t’ab = t’b-t’a = (tb-ta)+((bo-ao)/c). The formula t’ab = tab+((bo-ao)/c) is the nanosecond formula.

John C. Huang (talk) 02:29, 19 May 2008 (UTC)

 * An "experiment just finished this morning" belongs in the realm of Original Research. Wikipedia does not deal with Original Research.
 * I have reverted your most recent edits to the pages talk:Time and talk:Lorentz transformation and left another warning on your talk page. How many times and in how many way do we have to explain this to you? DVdm (talk) 14:45, 19 May 2008 (UTC)

"Under the Erlangen program, the space-time (no longer spacetime)" what does that mean? ("no longer spacetime"). 217.132.109.1 (talk) 07:21, 5 November 2008 (UTC)

Please, explain the "operators"
My problem when reading this article was the lack of introduction of the "operators", E, C etc. Which transformations are they associated with? Why is there a hbar in this. I believe Galilei was unaware of quantum mechanics. It would be much better to use operators without hbars. Anyone ready to contemplate the Lie-algebra aspect of GT, will not be particularly disturbed by this deviation from the standard qm-textbook variants. —Preceding unsigned comment added by 212.37.14.186 (talk) 14:06, 28 April 2009 (UTC)

x' ≠ x - vt
I am a first time writer to Wikipedia and would appreciate some comments. Please note, that this is a mathematical challenge to this equation. That is, by letting vt = distance (d) my challenge is to x' = x - d. In no manner then, is this related to any Physics concerns, such as time, motion, observers, light, time dilation, length contraction, wave-fronts, velocity, etc.

My math challenge of x' ≠ x - vt since x' ≠ x - d

Given x = +2 and d = +3

Then according to x' = x - d, x' = -1.

However, Woldemar Voigt's 1887 equation, and consequently Relativity's x' = x - d should instead be

x' = x + d, where x' = 5.

The length of 3 is not a coordinate ( in the unmoved frame ) since it goes from -1 to + 2. By definition, all coordinate lengths must start from 0,0,0 in their own frame.

Please excuse my jumping the gun and editing the on-line article. I was under the impression it was to be screened first. Hopefully, this page/place is the correct procedure to follow. I do hope for some feedback/discussion/criticism/critique.

Steve waterman (talk) 17:49, 16 September 2009 (UTC)

 * Remarks:
 * "'... 'by letting vt = distance (d) ...''" => Here you go wrong already. Distance is a positive quantity, whereas the time coordinate of an event can be positive or negative. A time coordinate is zero for all events simultaneous with the null-marking of a clock. An event taking place before the null-mark has a negative time coordinate. An event taking place after the null-mark has a positive time coordinate. Likewise, a velocity in the positive x-direction is modelled with a positive value for v, whereas a velocity in the negative x-direction is modelled with a positive value for v. So the product vt can be positive or negative. Distances cannot be negative, by definition. The x-coordinate and the x'-coordinate of an event can be negative or positive.
 * "Please note, that this is a mathematical challenge to this equation." => Please note that is an article about a topic in physics. Unlike in mathematics, in physics the variables in an equation have a physical meaning. Physics is not just another application of algebra.
 * DVdm (talk) 18:47, 16 September 2009 (UTC)

"Here you go wrong already." So vt ≠ d ? http://www.1728.com/velocity.htm Please show your reference that vt ≠ d. I believe every textbook will allow velocity times time = distance.

Time is not relevant as I mentioned. The problem exists mathematically, AFTER the frame has moved 3 and stopped.

"Please note that is an article about a topic in physics." I am saying that the foundation for that Physics is based upon a math error... and thus has implications directly related to Relativity.

—Preceding unsigned comment added by Steve waterman (talk • contribs) 20:02, 16 September 2009 (UTC)

 * Remarks:
 * "So vt ≠ d ?" => Quite indeed, not with the definitions of v (velocity) and t (time coordinate) as they are used in the article, combined with the definition of d (distance) which you seem to have in mind. I tried to explain that the product of a time coordinate with a velocity is a location coordinate and not a distance. As opposed to the former, the latter is positive by definition. Please re-read my previous comment until you understand. Again, physics is not just another application of algebra.
 * "Time is not relevant as I mentioned" => Since the symbol t represents a time coordinate in the article, time is highly relevant. If you say it is not relevant, you are working outside the context of the article. Please note that an article's talk page is not meant to help readers understand the subject, get rid of their misconceptions, or entertain them about unrelated subjects, but to discuss the content and format of the article in question. I'm afraid you really have come to the wrong place with this.
 * DVdm (talk) 20:32, 16 September 2009 (UTC)

I thought using vt = d was going to be easier, it has not been so in this particular discussion. So I will just stick to the original equation.

My math challenge of x' ≠ x - vt

Given x = +2,0 and vt = +3

Then according to x' = x - vt, or x - vt, then x' = -1 after x' having been transformed to the unmoved frame.

However, Woldemar Voigt's 1887 equation, and consequently Relativity's x' = x - vt should instead be x' = x + vt, where x' = 5.

The length of 3 is not a coordinate ( in the unmoved frame ) after being transformed to the unmoved frame, since it extends between -1 to + 2.

question - Do you agree that the length of 3 is not a coordinate in the unmoved frame after being transformed to the unmoved frame ?

Noting that by definition, all coordinate lengths must start from 0,0,0 in their OWN frame.

Of course time is used in the Wiki article, you missed my point, I believe. Time is not relevant to my math only challenge discussion.

"I'm afraid you really have come to the wrong place with this."

I do appreciate your responding in the discussion. I will drop this thread immediately, as soon as you can answer my one question above. Fair enough ? If you could supply a brief logic for your yes or no choice, I would much appreciate it. I will let you have the last word, which quite likely, I will not be in agreement with. I do understand the nature of your observation "wrong place". I admittedly am as far from aiding in the construction of the current Galilean page as perhaps one can get.

Steve waterman (talk) 17:19, 26 September 2009 (UTC) —Preceding unsigned comment added by Steve waterman (talk • contribs) 22:22, 16 September 2009 (UTC)

 * Remarks:
 * "Given x = +2,0 and vt = +3. Then according to x' = x - vt, or x - vt, then x' = -1". => In the article's context where "x' = x - vt" this means:
 * The (x',y',z',t') system moves with velocity v in the positive x-direction of the (x,y,z,t) system. At time t=t'=0 the origins of both systems coincide.
 * Some event takes place at some time t at location x=2 as measured in the (x,y,z,t) system, i.e. at a location at 2 distance units from the origin of the (x,y,z,t) system in the positive x-direction, i.o.w. in front of someone sitting at this origin and looking in the +x-direction.
 * As measured in the (x',y',z',t') system this same event takes place at location x'=-1, i.e. at a location at 1 distance unit from the origin of the (x',y',z',t') system in the negative x'-direction, i.o.w. behind someone sitting at this origin and looking in the +x'-direction.
 * "Time is not relevant to my math only challenge discussion." => As you are discussing an article equation in which time is modelled as a variable, tIme is extremely relevant.
 * "I admittedly am as far from aiding in the construction of the current Galilean page as perhaps one can get." => Then your remarks and your questions are not relevent to this article's talk page. <== Please click this link and aquaint yourself with the talk page guidelines. For starters, use indentation and sign your comments. Thanks.

 * DVdm (talk) 07:03, 17 September 2009 (UTC)

 * As measured in the (x',y',z',t') system this same event takes place at location x'=-1, i.e. at a location at 1 distance unit from the origin of the (x',y',z',t') system in the negative x'-direction, i.o.w. behind someone sitting at this origin and looking in the +x'-direction.

Thank you for your nicely detailed response and that your made a numerical choice; being -1.

Quoting you from just above- As measured in the (x',y',z',t') system this same event takes place at location x'=-1

We likely agree that at t = 0 that x = 2 and x' = 2, being coincident frames at t = 0, therefore if x is present at t= 0, so too must be x'.

The transformation is to determine what the value of x' [ which is now at 2 at t = 0, ] is in the x,y,z,t system AFTER the (x',y',z',t') system has gone +3. You will disagree surely, believing it to be what x is transformed to AFTER the (x',y',z',t') system has gone +3.

Thus you would get the result ...What is x (2) in the (x',y',z',t') system ? x = -1 um, since x = 2, then in reference to the (right-moved x',y',z',t') system - the (x,y,z,t) system is itself left moved, relatively speaking. Obviously, if two systems are coincident, then moving one right moves the other left relative to each another.

What is x' (2) in the (x',y',z',t') system transformed value in the (x,y,z,t) system ? x' = +5

According to the equation, we what to know what x' is in the (x,y,z,t) system as would seem evident by the fact the equation was solved for x'. x' [the (x',y',z',t') system ] = x - vt the (x',y',z',t'] system.

I no longer need you to answer my previous question that was not addressed. I will keep my word then, and will make this my last post here. I really do thank you for playing along with my given values and representing your position. I will look for a response to this assessment above, hopefully.

Recap - are we not trying to transform a point x' from the (x',y',z',t') system to the (x,y,z,t) system ?

Think about it please....you have a point x' at 2 and a point x' at 2 at t = 0 and you move the (x',y',z',t') system three places to the right. Where is x' now in relationship to the (x,y,z,t) system ? I know it is most impossible to believe that we all got this wrong.

So we agree that x was transformed to -1 in the (x',y',z',t') system.

x = 2  vt = 3

If we solve x' = x - vt for x, we get x = x' + vt = 2 + 3 = +5.

relativity  x = -1  x' = 5 reality     x = -1  x' = 5 We agree where the transformed points end up; at -1 and +5, but not the direction.

x = -1 in the (x',y',z',t') system x' = 5 in the (x,y,z,t) system

FINAL  SYNOPSIS given x = 2  vt = 3. Relativity says x' = x - vt = -1 and x = x' + vt = +5. However, x to x'y'z't = -1 and  x' to  xyzt = +5

and we disagree about directions. While in fact x' = x + vt = 5   and  x = x' - vt = -1. x ≠ x - vt  ≠ -1  and  x ≠ x' + vt ≠ 5.

.............................................

You may only be considering point x = 2 at t = 0 ???

However, at t = 0, if x = 2 in the (x,y,z,t) system then the (x',y',z',t') system MUST also have a point x' at 2.

After all, by definition they are coincident systems. This is absolutely critical to agree upon this above singular issue or not. As the (x',y',z',t') system moves to the right, that point X' at 2 in the (x',y',z',t') system ALSO moves to the right. It goes three and ends up at 5.

I believe relativity would just say x = 2 vt = 3. So x' = -1 and even if we solve for x, being x' + vt...we still get x' to be -1. Again likely you see 5, that is x' in the x,y,z,t) system as not involved at all. It certainly depends upon there also being at point x' at 2, at t = 0, should x be 2.  Coincident frames have coincident points.

Perhaps worse even yet, one can be further be mislead by the sheer fact that EVERY x point in the (x,y,z,t) system is now vt greater than EVERY x' point in the (x',y',z',t') system. Which would also make it seem that x = x' + vt is true. whereas, X' in the (x',y',z',t') system, is 2 at t = 0, and 5 after vt is completed. So, in fact X' = X + vt. Steve waterman (talk) 17:19, 26 September 2009 (UTC)

 * Please note that you are disrupting this talk page. Do have a look at your user talk page. Thank you. DVdm (talk) 08:25, 19 September 2009 (UTC)

If you wish to remove my thread from the discussion, I am okay with that. I would be pleased if you do allow it to remain. In conclusion, I have finished a video of 2 and a half minutes that portraits my contention much clearer than I could do here. I would like to thank you Dr. Rick for your feedback upon this issue. I hope you will at least enjoy the accompanying music. http://watermanpolyhedron.com/videoforweb17-show0.html This video replaces the url that was here before as I was informed that some could not view it. Steve waterman (talk) 17:19, 26 September 2009 (UTC)

Spacetime video?
Surely that video of spacetime distorting with velocity changes in accordance with Einstein's relativity shouldn't be on a page about Galilean relativity? 165.124.205.18 (talk) 23:27, 8 June 2010 (UTC)

 * Huh? That video uses the Galilean transformation, not the Lorentz transformation. mike4ty4 (talk) 10:27, 31 December 2010 (UTC)

About Translation
The last sentence of Tanslation stated {Note that the last equation expresses the assumption of a universal time independent of the relative motion of different observers.} I think that is just one of the explanations for {t'=t}. There are at least two other ways to explain {t'=t}:

1. If the speed of light is infinitely fast, then, the picture of event-happening will be sent to all observers instantly so that all observers will record same event time t'=t.

2. If we assign observers at the location where the event is happening to record event time for their systems, then, since observers are all at the same place with zero distance from the event-location, they should record same event time t'=t.

Actually, the assumption of a universal time is not as clearly defined as above two explanations for the possible relation of t'=t. Because the Galilean Transformation (GT) is dealing with two sets of records for the same event eA, happens at a time tA and a location A. If in the stationary system (t,x,y,z), named S, the recorded time is tA=t and coordinate of A is A(x,y,z) while in the moving system (t',x',y',z'), named S', the recorded time is tA=t' and the coordinate of A is A(x',y',z'), then, GT states (t',x',y',z')=(t,x-vt,y,z). As you can tell, the assumption of a universal time does not care about that {an actual observation} is related to LIGHT, hence, the distance away from event or the speed of light should be handled. That assumption does not care about the distance away from event, nor the speed of light, so that it is not a detailed expalnation for t'=t, I think.

John Huang Jh17710 (talk) 05:14, 23 October 2010 (UTC)

transformed axis graph at t=0
Hi. I think it wouldn't hurt to have a graph similar to this one: http://www.phys.vt.edu/~takeuchi/relativity/notes/Lorentz-STD.gif — Preceding unsigned comment added by 78.179.87.40 (talk) 11:01, 9 September 2011 (UTC)

Perhaps a different approach
My 2c worth: The approach that this article currently takes, namely that the Galilean transformation is something only used in Newtonian physics helps perpetuate the confusion that existed in the early 20th century and which still persists today regarding relativity and continues to make relativity so difficult to understand or even accept. The Galilean transformation is a logically - indeed trivially logical - proveable transformation between ordinary Cartesian coordinates and a set of convenient generalized coordinates used in the analysis of a systrem moving at a constant velocity v relative to the observer. Standard Cartesian coordinates are projections of the positions of objects in the system onto the stationary axes of the observers reference frame. The Galilean transformation transforms these standard coordinates into a set of generalized coordinates consisting of projections of the positions of the objects onto a set of axes which according to the observer are moving with the same velocity as the system being analyzed. This really isn't any different to using any other generalized coordinates to simplify the analysis of a system and it is valid regardless of special reletivity. Saying that the Galilean transformation doesn't hold for relativity is what confuses people and creates misunderstanding and makes relativity sound like hocus pocus. The real issue leading to special relativity and the Lorentz transformation comes in when we introduce a second obsever and wish to convert from the standard Cartesian coordinates of the first observer to those of the second. That is where the Lorentz transformation is needed and where the Galilean transformation is the wrong tool, because that is not what the Galilean transformation is doing. The reason its not doing that is that all observers measure time and space against their own perception of electromnagnetic signals traveling between them and the objects being observed and thus in particular they all measure the speed of light to be same - its like if everyone used their own hand to measure length and then marvelled at the fact that everyone found their own hand to be exactly one hand long :) Because every observer measures with his "own hand", the Galilean transformation is not a conversion from one observers frame to anothers - we need the Lorentz transformation which scales "hand length" so to speak. However the Galilean transformation is still valid as a transformation used by a _single_ observer going from standard to convenient general coordinates. Kuratowski's Ghost (talk) 14:36, 10 December 2012 (UTC)

This article is missing so much information.
I would expect this article to have the following sections:

1. Some discussion of the relation between Galilean Transformation and Newton's First Law. Note that the standard physics version of the Galilean transformation does not include transformations to rotating or accelerating frames, since those are non-inertial frames.

2. Galilean Transformations in Dynamics; Transformation of displacement, velocity(1D, 2D, 3D), momentum, kinetic energy.

3. Galilean Transformations in systems of particles; Center of Mass Transformtions; Galilean Transformations in Fluids

4. Invariance of Classical Lagrangians under Galilean Transformations

5. Galilean Transformations in non-relativistic Quantum Mechanics; Relation to Unitary Operator, Momentum operator

6. An independent section discussing the limitations/extensions of Galilean transformation to Relativistic Phenomena. It is tiresome when the article mentions special relativity every other paragraph.

7. The stuff on group theory really seems to pertain to the Galilean Group (which is Galilean boost, translation, rotation, time translation) and not specifically to the Galilean transformation. The equations should really be limited to the article on the Galilean Group (which has several other issues of its own). And maybe just a paragraph in this article about how the galilean transformation is one part of a larger class of transformations known as the Galilean Group with a link.

70.124.92.52 (talk) 16:36, 26 October 2013 (UTC)

 * Go ahead and fix it. - DVdm (talk) 20:18, 26 October 2013 (UTC)

I'll get to work on it 70.124.92.52 (talk) 14:23, 1 November 2013 (UTC)

What is i ?
Some of the commutation relations like $$[C_i,H] = i P_i$$ use a multiplicative i. But isn't the Lie algebra of the Galilean group a real algebra? Isn't there a confusion in the article with Representation_theory_of_the_Galilean_group and Quantum mechanics considerations? 94.245.87.72 (talk) 09:30, 5 November 2013 (UTC)

title: Talk:Galilean transformation


text:
List of historic houses in Massachusetts

This is a list of historic houses in Massachusetts.

Berkshire County

 * Lenox
 * The Mount (Lenox) – author Edith Wharton's estate; 1902
 * Ventfort Hall (Lenox) – Jacobean style mansion, built 1893 – George & Sarah Morgan (sister of J.P. Morgan)
 * Frelinghuysen Morris House and Studio – home of American Abstract Artists George L.K. Morris and Suzy Frelinghuysen; 1930–1941
 * Pittsfield
 * Arrowhead (Pittsfield) – home of author Herman Melville; built 1780
 * Stockbridge
 * Chesterwood (Stockbridge) – sculptor Daniel Chester French's home and studio; 1920s
 * Merwin House (Stockbridge) – Federal-style house built c. 1825
 * The Mission House (Stockbridge) – the first missionary to the Mohegan Indians in Stockbridge; built in 1739
 * Naumkeag (Stockbridge) – 44 room, Shingle-style country house designed by Stanford White; 1885
 * Elsewhere
 * Anthony House (Adams) – birthplace of Susan B. Anthony
 * Colonel John Ashley House (Sheffield) – built c. 1735
 * Bidwell House Museum (Monterey) – built 1750
 * The Folly (Williamstown) – designed by Ulrich Franzen, 1966
 * Santarella (Tyringham) – home of sculptor Henry Hudson Kitson

Franklin County

 * Deerfield
 * Sheldon–Hawks House (Deerfield) – built in 1743
 * Greenfield
 * Leavitt–Hovey House (Greenfield) – built in 1799 by architect Asher Benjamin for judge Jonathan Leavitt

Hampden County

 * Agawam
 * Capt. Charles Leonard House, built in 1805, designed by Asher Benjamin
 * Purchase-Ferre House, built in 1764, owned by the Ferre family since 1799
 * Thomas and Esther Smith House, built in 1757, example of vernacular Georgian architecture
 * Chicopee
 * Edward Bellamy House, built in 1852, home of Utopian writer Edward Bellamy
 * Thomas D. Page House, c. 1875, used as freemason lodge, 1909–2012
 * East Longmeadow
 * Elijah Burt House, c. 1720–1740, station of Underground Railroad
 * Swetland-Pease House, c. 1793
 * Granville
 * John and Ruth Rose House, built in 1742
 * Hampden
 * Laughing Brook Wildlife Sanctuary (Hampden) – home of author Thornton Burgess
 * Captain John Porter House, built in 1771 in Agawam
 * Thornton W. Burgess House, c. 1780–1784
 * Holyoke
 * Wistariahurst built in 1868 for William Skinner
 * Monson
 * Jacob Thompson House, c. 1811–1813, rare example of Federal style with brick ends
 * William Norcross House, c. 1785, example of late Georgian architecture
 * Southwick
 * Laflin-Phelps Homestead, c. 1808–1821, owned by the Phelps family since 1865
 * Springfield, Massachusetts
 * Mills-Stebbins Villa, built 1849–1851, considered architect Henry Sykes's "best work" in the Italianate style
 * Westfield
 * Joseph Dewey House, c. 1735
 * Octagon House, c. 1858–1864
 * West Springfield
 * Josiah Day House, built in 1754, oldest known brick saltbox

Hampshire County

 * Amherst
 * Dickinson Homestead (Amherst) – home of Emily Dickinson
 * Strong House, c. 1744, home of the Amherst Historical Society
 * Cummington
 * William Cullen Bryant Homestead (Cummington) – home of William Cullen Bryant
 * Hadley
 * Porter–Phelps–Huntington House (Hadley) – built between 1752 and 1799 and home of several generations of important local figures, including diarist Elizabeth Porter Phelps and bishop Frederic Dan Huntington
 * Samuel Porter House, 1713
 * Northampton
 * Historic Northampton, a museum of local history in the heart of the Connecticut River Valley of western Massachusetts. Its collection of approximately 50,000 objects and three historic buildings is the repository of Northampton and Connecticut Valley history from the pre-contact era to the present. Historic Northampton constitutes a campus of three contiguous historic houses, all on their original sites. The grounds themselves are part of an original Northampton homelot, laid out in 1654.
 * Isaac Damon House (1813), built by architect Isaac Damon, contains Historic Northampton's administrative offices and a Federal era parlor featuring Damon family furnishings and period artifacts. A modern structure, added in 1987, houses the museum and exhibition area. It features changing exhibits and a permanent installation, A Place Called Paradise: The Making of Northampton, Massachusetts, chronicling Northampton history.
 * Parsons House (1730) affords an overview of Colonial domestic architecture with its interior walls exposed to reveal evolving structural and decorative changes over more than two and a half centuries.
 * Shepherd House (1796) contains artifacts and furnishings from many generations, including exotic souvenirs from the turn-of-the-century travels of Thomas and Edith Shepherd, and reflects one family's changing tastes and values.
 * Shepherd Barn contains exhibits of antique farm implements, vehicles and a working blacksmith shop.

Worcester County

 * Auburn
 * Joseph Stone House – Central Chimney Cape house built c. 1729 35 Stone Street, Auburn.
 * Thaddeus Chapin House on Elmwood Street – Federal-style house built on west side of Pakachoag Hill in what is now Auburn.
 * Grafton
 * Willard House and Clock Museum
 * Shrewsbury
 * General Artemas Ward House
 * Rev. Joseph Sumner House, built in 1797
 * Worcester
 * Salisbury Mansion – built 1772
 * Judge Timothy Paine House – House is known as The Oaks (1774)
 * Captain Benjamin Flagg House – Central Chimney Cape house built c. 1717, 136 Plantation Street

Essex County

 * Amesbury
 * Mary Baker Eddy Historic House (Amesbury) – Mary Baker Eddy associations
 * Macy–Colby House (Amesbury) – built 1654
 * Isaac Morrill House – built 1680
 * John Greenleaf Whittier Home (Amesbury) – home of poet John Greenleaf Whittier
 * Andover
 * Amos Blanchard House (Andover) – house museum; late Federal period
 * Russell House (Andover) – c. 1805
 * Beverly
 * John Balch House (Beverly) – one of the oldest surviving timber-framed houses in the United States, built c. 1679
 * John Cabot House (Beverly) – one of the first brick structures built in Beverly
 * Exercise Conant House (Beverly) (Son of early Cape Ann settler Roger Conant) (Added on to by Reverend John Chipman

 * John Hale House (Beverly) – c. 1695
 * Long Hill (Beverly) – Ellery Sedgwick's home and gardens; 1925
 * Danvers
 * Judge Samuel Holten House (Danvers) – c. 1670
 * Rebecca Nurse Homestead (Danvers) – hanged for witchcraft, 1692
 * General Israel Putnam House (Danvers) – c. 1648, birthplace of Gen. Israel Putnam
 * Essex
 * Choate House (Essex) – birthplace of Rufus Choate; built c. 1730
 * Coffin House (Essex) – Colonial house; c. 1678
 * Gloucester
 * Beauport, Sleeper–McCann House – built in 1907 as a summer house for designer Henry Davis Sleeper
 * Captain Elias Davis House – built in 1804, part of Cape Ann Museum's decorative arts collection.
 * Hammond Castle – home and laboratory of John Hays Hammond Jr.; built 1926–1929
 * Sargent House Museum – built in 1782, home of writer Judith Sargent Murray and pastor John Murray
 * White–Ellery House – built in 1710 for Reverend John White, owned by the Ellery family for 200 years
 * Ipswich
 * John Heard House (Ipswich) – Western and Asian cultures in an atmosphere of the China trade years; built 1795
 * John Whipple House (Ipswich) – mid-17th century to the early 18th century
 * Ipswich has hundreds of historic houses, including 57–59 that are classified as First Period.
 * Marblehead
 * Ambrose Gale House - built in 1663
 * Jeremiah Lee Mansion - built in 1768
 * Newbury and Newburyport
 * Cushing House Museum and Garden (Newburyport) – home of shipowner John Newmarch Cushing
 * Dole–Little House (Newbury) – c. 1715 of older materials
 * Spencer–Peirce–Little Farm (Newbury) – c. 1675–1700
 * The Swett–Ilsley House (Newbury) – c. 1670
 * North Andover
 * The Capt. Timothy Johnson House - c. 1708, First Period Colonial home with historical ties to Indian Raids, the Salem Witch Trials, and The Underground Railroad
 * Salem
 * Andrew–Safford House was built in 1819
 * Bessie Monroe House was built in 1811
 * Bowker Place located at144–156 Essex Street and built in 1830
 * Crowninshield–Bentley House (Salem) – c. 1727–1730
 * Salem City Hall – Oldest continually run City Hall in America, built in 1837
 * Cotting–Smith Assembly House
 * Derby House built in 1762
 * Francis Cox House built in 1846
 * Gardner–Pingree House (Salem) – 1804–1805
 * Gedney House (Salem) – c. 1665
 * Hamilton Hall – A National Historic Landmark located at 9 Chestnut Street and built in 1805 by Samuel McIntire and added to the National Register of Historic Places in 1970.
 * Hawkes House – c. 1780, 1800
 * House of the Seven Gables (Salem) – house from the Nathaniel Hawthorne novel of the same name
 * John Bertram Mansion located in the McIntyre Historic District, High Style Italianate brick and brownstone mansion built in 1855. When John Bertram died in March 1882, his widow donated their home ( The John Bertram Mansion located at 370 Essex Street ) and this became the Salem Public Library. The Salem Public Library opened its doors on July 8, 1889, and is in the National Register of Historic Places.
 * John Bertram Mansion, built in 1818–19 – Located in the Salem Common Historic District and is a home for the elderly
 * John Tucker Daland House (Salem) – 1851–1852
 * Joseph Fenno House–Woman's Friend Society, 18th Century – Federal architecture
 * Joseph Story House was built in 1811 for U.S. Supreme Court Justice Joseph Story
 * Joshua Ward House was built in 1784
 * Joseph Winn Jr. House c. 1843
 * Narbonne House c. 1675
 * Nathaniel Hawthorne Birthplace (Salem) – birthplace of American novelist Nathaniel Hawthorne; built between 1730 and 1745
 * Nathaniel Bowditch House (Salem) – home of Nathaniel Bowditch (c. 1805)
 * Pedrick Store House c. 1770
 * Peirce–Nichols House located at 80 Federal Street, built in 1782
 * Phillips Library
 * Pickering House (Salem) – c. 1651
 * Ropes Mansion (Salem) – late 1720s
 * Rufus Choate House is located at 14 Lynde Street and was built in 1787
 * Salem Athenaeum
 * Shepard Block is a Greek Revival structure was constructed in 1851 and is located at 298-304 Essex Street
 * Stephen Phillips House is located at 34 Chestnut Street – c. 1806
 * Thomas March Woodbridge House is located at 48 Bridge Street – c. 1809
 * John P. Peabody House at 15 Summer Street – built in 1867
 * Salem Old Town Hall 1816–17, Federal Style building.
 * Quaker Meeting House
 * West Cogswell House is a historic set of row houses located at 5–9 Summer Street and built in 1834
 * William Pike House, 19th Century
 * Witch House (Salem) – c. 1642 – home of Witch Trials Judge Jonathan Corwin
 * William Murray House built in 1688
 * Yin Yu Tang House, was built around 1800 in China. 200 years after construction the Yin Yu Tang House was disassembled in China, shipped to America and then reassembled inside the Peabody Essex Museum.
 * Swampscott
 * Mary Baker Eddy Historic House (Swampscott) – Mary Baker Eddy home (1865–66)
 * Sir John Humphreys House (Swampscott) – built by first Deputy Governor of Massachusetts
 * Elihu Thomson House (Swampscott) – home of Elihu Thomson
 * General Glover House – 1750s home of General John Glover
 * Elsewhere
 * Boardman House (Saugus) – c. 1687
 * Brocklebank–Nelson–Beecher House (Georgetown) – c. 1668
 * Claflin–Richards House (Wenham) – c. 1690
 * Cogswell's Grant (Essex) – remarkable collectors' house
 * Mary Baker Eddy Historic Home (Lynn) – first home owned by Mary Baker Eddy
 * Jeremiah Lee Mansion (Marblehead) – 1768
 * The Stevens–Coolidge Place (North Andover) – house museum and garden; late Federal period
 * John Greenleaf Whittier Homestead (Haverhill) – home of poet John Greenleaf Whittier
 * Parson Capen House (Topsfield) – c. 1683

Middlesex County

 * Arlington
 * Jason Russell House (Arlington) – Bloodiest spot in the Battle of Lexington and Concord; built 1740
 * Fowle-Reed-Wyman House (Arlington) - Oldest house in Arlington; c. 1706
 * Burlington
 * Wyman House (Burlington) – oldest house in Burlington, built c. 1666
 * Cambridge
 * Cooper–Frost–Austin House (Cambridge) – oldest house in Cambridge; built c. 1681
 * Elmwood (Cambridge) – birthplace and home of poet James Russell Lowell; built 1767
 * Asa Gray House (Cambridge) – designed by Ithiel Town, home of botanist Asa Gray
 * Hooper–Lee–Nichols House (Cambridge) – 2nd oldest house in Cambridge; 1685
 * Longfellow House–Washington's Headquarters National Historic Site - built 1759
 * Chelmsford
 * Barrett–Byam Homestead – (Chelmsford) – prior to 1663
 * "Old Chelmsford" Garrison House – (Chelmsford) – prior to 1691
 * Concord
 * The Old Manse (Concord) – built by Ralph Waldo Emerson's grandfather; Emerson and Nathaniel Hawthorne wrote some of their work in the house; 1770
 * Orchard House (Concord) – home of Louisa May Alcott; the novel Little Women was written here
 * The Wayside (Concord) – built circa 1717; later the home of Samuel Whitney, a Minuteman who fought the British regulars at the North Bridge on April 19, 1775; home of Louisa May Alcott and her family 1845–1848; home of Nathaniel Hawthorne and his family 1852–1870; purchased in 1883 by Boston publisher Daniel Lothrop and his wife, author Harriett Lothrop (pen name Margaret Sidney), whose descendants lived in the house until it was acquired by the National Park Service in 1965.
 * Bush, Ralph Waldo Emerson House (Concord) – home of Ralph Waldo Emerson
 * Reuben Brown House – Colonial style built in 1725
 * Thoreau Birth House—Built by John Wheeler circa 1730; Henry David Thoreau born in the house in 1817; house moved 300 yards to its current location in 1878.
 * Robbins House—Built circa 1790–1800; home of Caesar Robbins, a formerly enslaved African-American and Revolutionary War veteran. In 1870–71, the house was moved to Bedford Street, near Sleepy Hollow Cemetery. In 2011 it was moved to its present site at 320 Monument Street, across from the Old North Bridge and the Old Manse.
 * Lexington
 * Hancock–Clarke House (Lexington) – home of the Reverend John Hancock (grandfather of John Hancock, signer of the Declaration of Independence) and the Reverend Jonas Clarke; built between 1698 and 1738 in Lexington, Massachusetts
 * Lincoln
 * Codman House (Lincoln) – Federal style; built 1735
 * Gropius House (Lincoln) – designed by Walter Gropius; 1938
 * Hoar Tavern (Lincoln) – Oldest home in Lincoln; built 1680
 * Malden
 * Cox-Haven House (Malden) – One of three Stations in Malden that hid Fugitive slaves on the Underground Railroad. The home was also the birthplace of Gilbert Haven Jr. (1821- 1880), the great social reformer and bishop of the Methodist Church. Today located at 35 Clifton St.; built 1790
 * Medford
 * Grandfather's House (Medford) – original destination from "Over the River and Through the Woods"
 * Isaac Royall House (Medford) – a very fine mansion from the early 18th century with New England's only surviving slave quarters
 * Peter Tufts House (Medford) – perhaps the oldest all-brick house in the United States
 * Lowell
 * Whistler House Museum of Art (Lowell) – birthplace of painter James McNeill Whistler
 * Natick
 * Sherman Geissler House – Roger Sherman was a member of the five man drafting committee the "Committee of Five" that wrote the first draft of the Declaration of Independence. In the famous painting by John Trumbull entitled "The Declaration Of Independence" Roger Sherman is depicted literally front and center. He was the only person that signed ALL four great state papers of the United States; The Continental Association, the Declaration of Independence, the Articles of Confederation and the Constitution. He built this house in 1750 in the Bean Hill section of Norwich CT. The house was moved from Norwich, CT to Natick, MA. in 1934
 * Henry Wilson Shoe Shop – Henry Wilson, eighteenth Vice President of the United States, made shoes in this ten footer.
 * Newton
 * Dupee Estate–Mary Baker Eddy Home
 * Reginald A. Fessenden House (Newton) – home of technologist Reginald Aubrey Fessenden
 * Somerville
 * Samuel Gaut House (Somerville) – Italianate style; built 1855
 * Stoneham, Massachusetts
 * Jonathan Green House (Stoneham) – built c. 1720
 * Shoe Shop–Doucette Ten Footer, 1850 ten footer
 * Townsend
 * Reed Homestead (Townsend) – murals by Rufus Porter, founder of Scientific American
 * Stow
 * Randall–Hale homestead - built c. 1710
 * Sudbury
 * Wayside Inn – oldest operating inn in the country, from 1716. Grounds contain one-room schoolhouse associated with the poem Mary Had a Little Lamb.
 * Waltham
 * Gore Place (Waltham) – brick country estate; built 1806
 * Lyman Estate (Waltham) – country estate; built 1793
 * Robert Treat Paine Estate (Waltham) – country estate, collaboration of Henry Hobson Richardson and Frederick Law Olmsted; built 1866 and 1884
 * Watertown
 * Abraham Browne House (Watertown) – c. 1694–1701
 * Edmund Fowle House (Watertown) – site of revolutionary government and first US treaty; early 1740s
 * Woburn
 * 1790 House (Woburn) – large Federal house with interesting history; 1790
 * Baldwin House (Woburn) – home of engineer Col. Loammi Baldwin; 1661
 * Benjamin Thompson House–Count Rumford Birthplace (Woburn) – birthplace of Benjamin Thompson, also known as Count Rumford

Norfolk County

 * Quincy
 * John Adams Birthplace (Quincy) – birthplace of John Adams
 * John Quincy Adams Birthplace (Quincy) – birthplace of John Quincy Adams
 * The Josiah Quincy House (Quincy) – country home of Revolutionary War soldier Colonel Josiah Quincy;1770
 * Peacefield (Quincy) – home of several generations of the Adams family
 * Brookline
 * John F. Kennedy National Historic Site, the birthplace of JFK
 * George R. Minot House (Brookline) – home of George R. Minot
 * Dedham
 * Endicott Estate Dedham, Massachusetts – home of Henry B. Endicott, designed by Henry Bailey Alden, 1905
 * Endicott House Dedham, Massachusetts – home of H. Wendell Endicott, designed by Charles A. Platt with landscape by Frederick Law Olmsted, 1934
 * Fairbanks House (Dedham) – North America's oldest surviving timber-frame house; built c. 1641
 * Needham
 * Jarvis Thorpe House (Needham) – Built in 1836, served as Needham's Post Office as well as home to the influential Thorpe family.
 * Elsewhere
 * Captain Robert Bennet Forbes House (Milton) – Greek Revival architecture
 * Eleanor Cabot Bradley Estate (Canton) – country house with garden grounds
 * General Sylvanus Thayer Birthplace (Braintree) – birthplace of Sylvanus Thayer, "Father of West Point"

Suffolk County

 * Boston
 * First Harrison Gray Otis House (Boston) – by Charles Bulfinch
 * Second Harrison Gray Otis House (Boston) – by Charles Bulfinch
 * Third Harrison Gray Otis House (Boston) – by Charles Bulfinch
 * Amory–Ticknor House (Boston) by Charles Bulfinch
 * Isabella Stewart Gardner Museum (Boston) – Remarkable palazzo and art museum
 * Gibson House Museum (Boston) – unchanged Back Bay townhouse lived in by 3 generations of Gibsons; built 1859
 * Paul Revere House (Boston) – built in 1680
 * Pierce–Hichborn House (Boston) – an early Georgian house; 1711
 * Nichols House Museum (Boston) - by Charles Bulfinch
 * Dorchester
 * James Blake House (Dorchester) – oldest house in Boston; 1648
 * Captain Lemuel Clap House (Dorchester) – built for a descendant of an original settler; 1710 and 1765
 * William Clapp House (Dorchester) – Federal style with Greek Revival addition; 1806
 * Pierce House (Dorchester, Massachusetts) - First period house; c. 1683
 * Roxbury
 * William Lloyd Garrison House (Roxbury) – William Lloyd Garrison's home
 * Shirley–Eustis House (Roxbury) – Tory stronghold
 * Edward Everett Hale House (Roxbury)- Home of famed author and minister Edward Everett Hale; 1841
 * Elsewhere
 * Loring–Greenough House (Jamaica Plain) – Tory stronghold
 * Ellen Swallow Richards House (Jamaica Plain) – home of Ellen Swallow Richards

Bristol County

 * Dartmouth
 * Elihu Akin House – cape-style house built; built in 1762
 * Fall River
 * David M. Anthony House – Second Empire style, built 1875
 * Ariadne J. and Mary A. Borden House – Second Empire, built 1882
 * Borden–Winslow House – Georgian Colonial, built 1740
 * Lafayette–Durfee House – Georgian Colonial, built about 1750
 * William Lindsey House – Greek Revival, built 1844
 * Luther Winslow Jr. House – Federal, built 1875
 * Osborn House – Greek Revival, built 1843
 * Mansfield
 * Fisher-Richardson House - built 1743
 * New Bedford
 * Rotch–Jones–Duff House and Garden Museum – home of William Rotch Jr., a whaling merchant; built in 1834
 * Rehoboth
 * Christopher Carpenter House – built 1800
 * Col. Thomas Carpenter III House – built 1855
 * Carpenter House (Rehoboth, Massachusetts) – built 1789
 * Taunton
 * J.C. Bartlett House – built, 1880
 * Samuel Colby House – Italianate, built 1869
 * McKinstrey House – Georgian colonial, built 1759
 * Morse House – built 1850
 * William L. White Jr. House – Second Empire, built 1873

Plymouth County

 * Duxbury
 * Alden House Historic Site (Duxbury) – purportedly built by the Pilgrim John Alden; originally thought built in 1653, though later evidence suggests c. 1700
 * King Caesar House (Duxbury) – home of Ezra Weston, II ("King Caesar"); built 1808
 * Nathaniel Winsor Jr. House (Duxbury) – built 1807
 * Plymouth
 * Harlow Old Fort House (Plymouth) – built with timbers from the Pilgrims 1621 Fort on Burial Hill; built in 1677
 * The Jabez Howland House (Plymouth) – home of Mayflower passenger John Howland; built in 1667
 * Richard Sparrow House (Plymouth) – oldest house in Plymouth; owned by the Sparrow family, who arrived Plymouth in 1633; the house was built c. 1640
 * Hingham
 * Samuel Lincoln House (Hingham) – built by Samuel Lincoln 1721 on land purchased in 1649 by grandfather Samuel Lincoln, ancestor of President Abraham Lincoln
 * Elsewhere
 * Isaac Winslow House (Marshfield) – Tory stronghold
 * Old Oaken Bucket Homestead (Scituate) – scene of Samuel Woodworth's poem "The Old Oaken Bucket"
 * Daniel Webster Estate (Marshfield, Massachusetts) – site of Webster Law Office and Webster Family home

Barnstable County

 * Atwood House Museum, Chatham – built 1756
 * Isaac Crocker Homestead, Marstons Mills – built c. 1750s
 * Winslow Crocker House, Yarmouth Port – built c. 1780
 * Hoxie House, Sandwich – Cape Cod's oldest saltbox house; built c. 1675
 * Wing Fort House, East Sandwich, Massachusetts – built ca. 1641

Dukes County

 * The Vincent House, Martha's Vineyard – oldest house in Martha's Vineyard; built c. 1672
 * The Thomas Chase House, Martha's Vineyard – oldest house in downtown Vineyard Haven; built c. 1717

Nantucket County

 * Auld Lang Syne House, Nantucket Sconset – oldest house in Nantucket not on the original foundation, ca. 1675
 * Jethro Coffin House, Nantucket – oldest house in Nantucket on its original foundation; built c. 1686


text:
Prince Edward, Hong Kong

Prince Edward is an area of Mong Kok south of Tong Mi surrounding Prince Edward station in Kowloon, Hong Kong. Named after Prince Edward Road West, the Prince Edward station of the MTR rapid transit system is an interchange station on the Tsuen Wan and the Kwun Tong lines.

Location
Prince Edward is located in the northern part of Mong Kok on either side of Nathan Road, administratively under the Yau Tsim Mong District (until the mid-1990s part of the Mong Kok District). Prince Edward contains the northern end of Nathan Road. Prince Edward is shown on Google Maps as bounded by:

 * Boundary Street to the North
 * Waterloo Road to the East
 * Prince Edward Road West, Sai Yee Street and Bute Street to the South
 * Canton Road and Lai Chi Kok Road to the West

Transport
The area is served by the Prince Edward Station of the MTR rapid transit system on both the Tsuen Wan line and the Kwun Tong line. Access to Mong Kok East station includes an entrance via the MOKO shopping centre on Prince Edward Road West.

Policing
Mong Kok Police Station is on Prince Edward Road West. The police station is adjacent to Prince Edward MTR station exit B1.

Sport and recreation
Mong Kok Stadium is a sports venue with capacity of 6,769. It hosts Hong Kong Premier League football matches, with Southern and Kitchee currently ground-sharing the venue as their home ground. The stadium is run by the Leisure and Cultural Services Department of Hong Kong.

Markets
Although Prince Edward area is perceived as part of Mong Kok the following markets are closer to the Prince Edward station:
 * Flower Market Road (花墟道)
 * Goldfish Street (金魚街) or Goldfish Market — Centered around the section of Tung Choi Street
 * Yuen Po Street Bird Garden (園圃街雀鳥花園)
 * Ladies' Street (女人街, Ladies' market on Tung Choi Street)

title: Prince Edward, Hong Kong


text:
Glyceraldehyde

Glyceraldehyde (glyceral) is a triose monosaccharide with chemical formula C3H6O3. It is the simplest of all common aldoses. It is a sweet, colorless, crystalline solid that is an intermediate compound in carbohydrate metabolism. The word comes from combining glycerol and aldehyde, as glyceraldehyde is glycerol with one alcohol group oxidized to an aldehyde.

Structure
Glyceraldehyde has one chiral center and therefore exists as two different enantiomers with opposite optical rotation:

 * In the nomenclature, either  from Latin Dexter meaning "right", or  from Latin Laevo meaning "left"
 * In the R/S nomenclature, either R from Latin Rectus meaning "right", or S from Latin Sinister meaning "left"

While the optical rotation of glyceraldehyde is (+) for R and (−) for S, this is not true for all monosaccharides. The stereochemical configuration can only be determined from the chemical structure, whereas the optical rotation can only be determined empirically (by experiment).

It was by a lucky guess that the molecular geometry was assigned to (+)-glyceraldehyde in the late 19th century, as confirmed by X-ray crystallography in 1951.

Nomenclature
In the system, glyceraldehyde is used as the configurational standard for carbohydrates. Monosaccharides with an absolute configuration identical to (R)-glyceraldehyde at the last stereocentre, for example C5 in glucose, are assigned the stereo-descriptor. Those similar to (S)-glyceraldehyde are assigned an.

Chemical synthesis
Glyceraldehyde can be prepared, along with dihydroxyacetone, by the mild oxidation of glycerol, for example with hydrogen peroxide and a ferrous salt as catalyst.

Its cyclohexylidene acetal can also be produced by oxidative cleavage of the bis(acetal) of mannitol.

Biochemistry
The enzyme glycerol dehydrogenase (NADP+) has two substrates, glycerol and NADP+, and 3 products, D-glyceraldehyde, NADPH and H+.

The interconversion of the phosphates of glyceraldehyde (glyceraldehyde 3-phosphate) and dihydroxyacetone (dihydroxyacetone phosphate), catalyzed by the enzyme triosephosphate isomerase, is an intermediate step in glycolysis.

title: Glyceraldehyde


text:
Rashad Khalifa

Rashad Khalifa (رشاد خليفة; November 19, 1935 – January 31, 1990) was an Egyptian-American biochemist, closely associated with the United Submitters International (USI), an organization which promotes the practice and study of Quranism. Khalifa saw his role as purging the accretions that found their way into Islam via hadith and sunnah, which he claimed were corrupted. Similarly, he believed that previous revelations of God, such as the Bible, contained contradictions due to human interference (a concept known as tahrif). Instead, he believed that the beliefs and practices of Islam should be based on the Quran alone. He is also known for his claims regarding the existence of a Quran code, also known as The Number 19.

However, his changing views regarding the essence of faith, recorded in his two renditions of the Quran, and declaring himself as a divine messenger who communicated with Gabriel, drew opposition from other Muslims. On January 31, 1990, Khalifa was found stabbed to death inside the Mosque of Tucson, in Arizona, which he founded.

Life
Khalifa was born in Egypt on November 19, 1935. He obtained an honors degree from Ain Shams University, before he immigrated to the United States in 1959. He later earned a Master's Degree in biochemistry from University of Arizona and a Ph.D. from University of California, Riverside. He became a naturalized U.S. citizen and lived in Tucson, Arizona. He was married to an American woman and they had a son and a daughter together.

Khalifa worked as a science adviser for the Libyan government for about one year, after which he worked as a chemist for the United Nations Industrial Development Organization. He next worked as a senior chemist in Arizona's State Office of Chemistry in 1980.

He founded the United Submitters International (USI), an organization that promulgated his beliefs.

Doctrine
He saw his role as purging the accretions that found their way into Islam via hadith and sunnah, which he claimed were corrupted. Similarly, he believed that previous revelations of God, such as the Bible, contained contradictions due to human interference (a concept known as tahrif). Instead, he believed that the beliefs and practices of Islam should be based on the Quran alone.

Starting in 1968, Khalifa used computers to analyze the frequency of letters and words in the Quran. He published his findings in 1973 in the book Miracle of the Quran: Significance of the Mysterious Alphabets, in 1981 in the book The Computer Speaks: God's Message to the World, and in 1982 in the book Quran: Visual Presentation of the Miracle. Khalifa claimed that the Quran, unlike the Hadith, was incorruptible because it contained a mathematical structure based on the number 19, namely the Quran code or known as Code 19. For example, he claimed that this mathematical structure rejected the Quranic verses 9:128-129. Some Muslims objected to this interpretation. However, Khalifa believed this mathematical structure prevented the Quran from being adulterated and that it was proof of its divine authorship.

Khalifa's research did not receive much attention in the West. In 1980, Martin Gardner mentioned it in Scientific American. Gardner later wrote a more extensive and critical review of Khalifa and his work.

Assassination
On January 31, 1990, Khalifa was found stabbed to death inside the mosque of Tucson, Arizona, which he founded.

Nineteen years after the murder, on April 28, 2009, the Calgary Police Service arrested Glen Cusford Francis, a 52-year-old citizen of Trinidad and Tobago, on suspicion of having killed Rashad Khalifa. Investigators in Tucson learned that Francis, who was going by the name Benjamin Phillips, had begun his studies under Khalifa in January 1990. Phillips disappeared shortly after the slaying, and was said to have left the country. An investigation revealed Phillips and Francis were the same man when the police analyzed fingerprints found in Phillips' apartment. A specialty unit of the Tucson Police Department progressed in its investigation in 2006 and in December 2008, and was able to use DNA testing on forensic evidence from the crime scene to tie Francis to the assassination. In October 2009, a Canadian judge ordered Francis's extradition to the United States to face trial.

The trial for the murder began on December 11, 2012. On December 19, the jury, after a three-hour deliberation, found Glen Francis guilty of first-degree murder and sentenced him to life in prison. Prior to the Francis trial, James Williams, an alleged member of the Jamaat ul-Fuqra organization, was convicted of conspiracy in the slaying. Williams disappeared in 1994 on the day of his sentencing. In 2000, Williams was apprehended attempting to re-enter the United States and was sentenced to serve 69 years in prison. In 2003, his convictions were upheld on appeal by the Colorado Court of Appeals, except for one count of forgery.

title: Rashad Khalifa


text:
Room-temperature superconductor

A room-temperature superconductor is a hypothetical material capable of displaying superconductivity above 0 C, operating temperatures which are commonly encountered in everyday settings. As of 2023, the material with the highest accepted superconducting temperature was highly pressurized lanthanum decahydride, whose transition temperature is approximately 250 K at 200 GPa.

At standard atmospheric pressure, cuprates currently hold the temperature record, manifesting superconductivity at temperatures as high as 138 K. Over time, researchers have consistently encountered superconductivity at temperatures previously considered unexpected or impossible, challenging the notion that achieving superconductivity at room temperature was infeasible. The concept of "near-room temperature" transient effects has been a subject of discussion since the early 1950s.

Reports
Since the discovery of high-temperature superconductors ("high" being temperatures above 77 K, the boiling point of liquid nitrogen), several materials have been claimed, although not confirmed, to be room-temperature superconductors.

Corroborated studies
In 2014, an article published in Nature suggested that some materials, notably YBCO (yttrium barium copper oxide), could be made to briefly superconduct at room temperature using infrared laser pulses.

In 2015, an article published in Nature by researchers of the Otto Hahn Institute suggested that under certain conditions such as extreme pressure transitioned to a superconductive form  at 150 GPa (around 1.5 million times atmospheric pressure) in a diamond anvil cell. The critical temperature is 203 K which would be the highest Tc ever recorded and their research suggests that other hydrogen compounds could superconduct at up to 260 K.

Also in 2018, researchers noted a possible superconducting phase at 260 K in lanthanum decahydride at elevated (200 GPa) pressure. In 2019, the material with the highest accepted superconducting temperature was highly pressurized lanthanum decahydride, whose transition temperature is approximately 250 K.

Uncorroborated studies
In 1993 and 1997, Michel Laguës and his team published evidence of room temperature superconductivity observed on MBE deposited ultrathin nanostructures of BiSrCaCuO. These compounds exhibit extremely low resistivities orders of magnitude below that of copper, strongly non-linear I(V) characteristics and hysteretic I(V) behavior.

In 2000, while extracting electrons from diamond during ion implantation work, Johan Prins claimed to have observed a phenomenon that he explained as room-temperature superconductivity within a phase formed on the surface of oxygen-doped type IIa diamonds in a 10−6 mbar vacuum.

In 2003, a group of researchers published results on high-temperature superconductivity in palladium hydride (PdHx: x > 1) and an explanation in 2004. In 2007, the same group published results suggesting a superconducting transition temperature of 260 K, with transition temperature increasing as the density of hydrogen inside the palladium lattice increases. This has not been corroborated by other groups.

In March 2021, an announcement reported superconductivity in a layered yttrium-palladium-hydron material at 262 K and a pressure of 187 GPa. Palladium may act as a hydrogen migration catalyst in the material.

On 31st of December 2023 "Global Room-Temperature Superconductivity in Graphite" was published in the journal "Advanced Quantum Technologies" claiming to demonstrate superconductivity at room temperature and ambient pressure in Highly oriented pyrolytic graphite with dense arrays of nearly parallel line defects.

Retracted or unreliable studies

In 2012, an Advanced Materials article claimed superconducting behavior of graphite powder after treatment with pure water at temperatures as high as 300 K and above. So far, the authors have not been able to demonstrate the occurrence of a clear Meissner phase and the vanishing of the material's resistance.

In 2018, Dev Kumar Thapa and Anshu Pandey from the Solid State and Structural Chemistry Unit of the Indian Institute of Science, Bangalore claimed the observation of superconductivity at ambient pressure and room temperature in films and pellets of a nanostructured material that is composed of silver particles embedded in a gold matrix. Due to similar noise patterns of supposedly independent plots and the publication's lack of peer review, the results have been called into question. Although the researchers repeated their findings in a later paper in 2019, this claim is yet to be verified and confirmed.

Since 2016, a team led by Ranga P. Dias has produced a number of retracted or challenged papers in this field. In 2016 they claimed observation of solid metallic hydrogen in 2016. In October 2020, they reported room-temperature superconductivity at 288 K (at 15 °C) in a carbonaceous sulfur hydride at 267 GPa, triggered into crystallisation via green laser. This was retracted in 2022 after flaws in their statistical methods were identified and led to questioning of other data. In 2023 he reported superconductivity at 294 K and 1 GPa in nitrogen-doped lutetium hydride, in a paper widely met with skepticism about its methods and data. Later in 2023 he was found to have plagiarized parts of his dissertation from someone else's thesis, and to have fabricated data in a paper on manganese disulfide, which was retracted. The lutetium hydride paper was also retracted. The first attempts to replicate those results failed.

On July 23, 2023, a Korean team claimed that Cu-doped lead apatite, which they named LK-99, was superconducting up to 370 K, though they had not observed this fully. They posted two preprints to arXiv, published a paper in a journal, and submitted a patent application. The reported observations were received with skepticism by experts due to the lack of clear signatures of superconductivity. The story was widely discussed on social media, leading to a large number of attempted replications, none of which had more than qualified success. By mid-August, a series of papers from major labs provided significant evidence that LK-99 was not a superconductor, finding resistivity much higher than copper, and explaining observed effects such as magnetic response and resistance drops in terms of impurities and ferromagnetism in the material.

Metallic hydrogen and phonon-mediated pairing
Theoretical work by British physicist Neil Ashcroft predicted that solid metallic hydrogen at extremely high pressure (~500 GPa) should become superconducting at approximately room temperature, due to its extremely high speed of sound and expected strong coupling between the conduction electrons and the lattice-vibration phonons.

A team at Harvard University has claimed to make metallic hydrogen and reports a pressure of 495 GPa. Though the exact critical temperature has not yet been determined, weak signs of a possible Meissner effect and changes in magnetic susceptibility at 250 K may have appeared in early magnetometer tests on an original now-lost sample. A French team is working with doughnut shapes rather than planar at the diamond culette tips.

Organic polymers and exciton-mediated pairing
In 1964, William A. Little proposed the possibility of high-temperature superconductivity in organic polymers.

Other hydrides
In 2004, Ashcroft returned to his idea and suggested that hydrogen-rich compounds can become metallic and superconducting at lower pressures than hydrogen. More specifically, he proposed a novel way to pre-compress hydrogen chemically by examining IVa hydrides.

In 2014–2015, conventional superconductivity was observed in a sulfur hydride system (Hydrogen sulfide or ) at 190 K to 203 K at pressures of up to 200 GPa.

In 2016, research suggested a link between palladium hydride containing small impurities of sulfur nanoparticles as a plausible explanation for the anomalous transient resistance drops seen during some experiments, and hydrogen absorption by cuprates was suggested in light of the 2015 results in as a plausible explanation for transient resistance drops or "USO" noticed in the 1990s by Chu et al. during research after the discovery of YBCO.

It has been predicted that (scandium dodedecahydride) would exhibit superconductivity at room temperature – Tc between 333 K and 398 K – under a pressure expected not to exceed 100 GPa.

Some research efforts are currently moving towards ternary superhydrides, where it has been predicted that (dilithium magnesium hexadecahydride) would have a Tc of 473 K at 250 GPa.

Spin coupling
It is also possible that if the bipolaron explanation is correct, a normally semiconducting material can transition under some conditions into a superconductor if a critical level of alternating spin coupling in a single plane within the lattice is exceeded; this may have been documented in very early experiments from 1986. The best analogy here would be anisotropic magnetoresistance, but in this case the outcome is a drop to zero rather than a decrease within a very narrow temperature range for the compounds tested similar to "re-entrant superconductivity".

In 2018, support was found for electrons having anomalous 3/2 spin states in YPtBi. Though YPtBi is a relatively low temperature superconductor, this does suggest another approach to creating superconductors.

"Quantum bipolarons" could describe how a material might superconduct at up to nearly room temperature.

title: Room-temperature superconductor