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Jakarta Enterprise Beans

Jakarta Enterprise Beans (EJB; formerly Enterprise JavaBeans) is one of several Java APIs for modular construction of enterprise software. EJB is a server-side software component that encapsulates business logic of an application. An EJB web container provides a runtime environment for web related software components, including computer security, Java servlet lifecycle management, transaction processing, and other web services. The EJB specification is a subset of the Java EE specification.

Specification
The EJB specification was originally developed in 1997 by IBM and later adopted by Sun Microsystems (EJB 1.0 and 1.1) in 1999 and enhanced under the Java Community Process as JSR 19 (EJB 2.0), JSR 153 (EJB 2.1), JSR 220 (EJB 3.0), JSR 318 (EJB 3.1) and JSR 345 (EJB 3.2).

The EJB specification provides a standard way to implement the server-side (also called "back-end") 'business' software typically found in enterprise applications (as opposed to 'front-end' user interface software). Such software addresses the same types of problem, and solutions to these problems are often repeatedly re-implemented by programmers. Jakarta Enterprise Beans is intended to handle such common concerns as persistence, transactional integrity and security in a standard way, leaving programmers free to concentrate on the particular parts of the enterprise software at hand.

General responsibilities
The EJB specification details how an application server provides the following responsibilities:
 * Transaction processing
 * Integration with the persistence services offered by the Jakarta Persistence (JPA)
 * Concurrency control
 * Event-driven programming using Jakarta Messaging (JMS) and Jakarta Connectors (JCA)
 * Asynchronous method invocation
 * Job scheduling
 * Naming and directory services via Java Naming and Directory Interface (JNDI)
 * Interprocess Communication using RMI-IIOP and Web services
 * Security (JCE and JAAS)
 * Deployment of software components in an application server

Additionally, the Jakarta Enterprise Beans specification defines the roles played by the EJB container and the EJBs as well as how to deploy the EJBs in a container. Note that the EJB specification does not detail how an application server provides persistence (a task delegated to the JPA specification), but instead details how business logic can easily integrate with the persistence services offered by the application server.

History
Businesses found that using EJBs to encapsulate business logic brought a performance penalty. This is because the original specification allowed only for remote method invocation through CORBA (and optionally other protocols), even though the large majority of business applications actually do not require this distributed computing functionality. The EJB 2.0 specification addressed this concern by adding the concept of local interfaces which could be called directly without performance penalties by applications that were not distributed over multiple servers.

The EJB 3.0 specification (JSR 220) was a departure from its predecessors, following a new light-weight paradigm. EJB 3.0 shows an influence from Spring in its use of plain Java objects, and its support for dependency injection to simplify configuration and integration of heterogeneous systems. EJB 3.0 along with the other version of the EJB can be integrated with MuleSoft-v4 using MuleSoft certified PlektonLabs EJB Connector. Gavin King, the creator of Hibernate, participated in the EJB 3.0 process and is an outspoken advocate of the technology. Many features originally in Hibernate were incorporated in the Java Persistence API, the replacement for entity beans in EJB 3.0. The EJB 3.0 specification relies heavily on the use of annotations (a feature added to the Java language with its 5.0 release) and convention over configuration to enable a much less verbose coding style. Accordingly, in practical terms EJB 3.0 is much more lightweight and nearly a completely new API, bearing little resemblance to the previous EJB specifications.

Example
The following shows a basic example of what an EJB looks like in code:

The above defines a service class for persisting a Customer object (via O/R mapping). The EJB takes care of managing the persistence context and the addCustomer method is transactional and thread-safe by default. As demonstrated, the EJB focuses only on business logic and persistence and knows nothing about any particular presentation.

Such an EJB can be used by a class in e.g. the web layer as follows:

The above defines a JavaServer Faces (JSF) backing bean in which the EJB is injected by means of the  annotation. Its addCustomer method is typically bound to some UI component, such as a button. Contrary to the EJB, the backing bean does not contain any business logic or persistence code, but delegates such concerns to the EJB. The backing bean does know about a particular presentation, of which the EJB had no knowledge.

Types of Enterprise Beans
An EJB container holds two major types of beans:
 * Session Beans that can be either "Stateful", "Stateless" or "Singleton" and can be accessed via either a Local (same JVM) or Remote (different JVM) interface or directly without an interface, in which case local semantics apply. All session beans support asynchronous execution for all views (local/remote/no-interface).
 * Message Driven Beans (MDBs, also known as Message Beans). MDBs also support asynchronous execution, but via a messaging paradigm.

Stateful Session Beans
Stateful Session Beans are business objects having state: that is, they keep track of which calling client they are dealing with throughout a session and of the history of its requests, and thus access to the bean instance is strictly limited to only one client during its lifetime. If concurrent access to a single bean is attempted anyway the container serializes those requests, but via the  annotation the container can instead throw an exception. Stateful session beans' state may be persisted (passivated) automatically by the container to free up memory after the client hasn't accessed the bean for some time. The JPA extended persistence context is explicitly supported by Stateful Session Beans.
 * Examples:
 * Checking out in a web store might be handled by a stateful session bean that would use its state to keep track of where the customer is in the checkout process, possibly holding locks on the items the customer is purchasing (from a system architecture's point of view, it would be less ideal to have the client manage those locks).

Stateless Session Beans
Stateless Session Beans are business objects that do not have state associated with them. However, access to a single bean instance is still limited to only one client at a time, concurrent access to the bean is prohibited. If concurrent access to a single bean is attempted, the container simply routes each request to a different instance. This makes a stateless session bean automatically thread-safe. Instance variables can be used during a single method call from a client to the bean, but the contents of those instance variables are not guaranteed to be preserved across different client method calls. Instances of Stateless Session beans are typically pooled. If a second client accesses a specific bean right after a method call on it made by a first client has finished, it might get the same instance. The lack of overhead to maintain a conversation with the calling client makes them less resource-intensive than stateful beans.
 * Examples:
 * Sending an e-mail to customer support might be handled by a stateless bean, since this is a one-off operation and not part of a multi-step process.
 * A user of a website clicking on a "keep me informed of future updates" box may trigger a call to an asynchronous method of the session bean to add the user to a list in the company's database (this call is asynchronous because the user does not need to wait to be informed of its success or failure).
 * Fetching multiple independent pieces of data for a website, like a list of products and the history of the current user might be handled by asynchronous methods of a session bean as well (these calls are asynchronous because they can execute in parallel that way, which potentially increases performance). In this case, the asynchronous method will return a Future instance.

Singleton Session Beans
Singleton Session Beans are business objects having a global shared state within a JVM. Concurrent access to the one and only bean instance can be controlled by the container (Container-managed concurrency, CMC) or by the bean itself (Bean-managed concurrency, BMC). CMC can be tuned using the  annotation, that designates whether a read lock or a write lock will be used for a method call. Additionally, Singleton Session Beans can explicitly request to be instantiated when the EJB container starts up, using the  annotation.
 * Examples:
 * Loading a global daily price list that will be the same for every user might be done with a singleton session bean, since this will prevent the application having to do the same query to a database over and over again...

Message driven beans
Message Driven Beans are business objects whose execution is triggered by messages instead of by method calls. The Message Driven Bean is used among others to provide a high level ease-of-use abstraction for the lower level JMS (Java Message Service) specification. It may subscribe to JMS message queues or message topics, which typically happens via the activationConfig attribute of the  annotation. They were added in EJB to allow event-driven processing. Unlike session beans, an MDB does not have a client view (Local/Remote/No-interface), i. e. clients cannot look-up an MDB instance. An MDB just listens for any incoming message on, for example, a JMS queue or topic and processes them automatically. Only JMS support is required by the Java EE spec, but Message Driven Beans can support other messaging protocols. Such protocols may be asynchronous but can also be synchronous. Since session beans can also be synchronous or asynchronous, the prime difference between session- and message driven beans is not the synchronicity, but the difference between (object oriented) method calling and messaging.
 * Examples:
 * Sending a configuration update to multiple nodes might be done by sending a JMS message to a 'message topic' and could be handled by a Message Driven Bean listening to this topic (the message paradigm is used here since the sender does not need to know the number of consumers, their location, or even their exact type).
 * Submitting a job to a work cluster might be done by sending a JMS message to a 'message queue' and could also be handled by a Message Driven Bean, but this time listening to a queue (the message paradigm and the queue is used, since the sender doesn't have to care which worker executes the job, but it does need assurance that a job is only executed once).
 * Processing timing events from the Quartz scheduler can be handled by a Message Driven Bean; when a Quartz trigger fires, the MDB is automatically invoked. Since Java EE doesn't know about Quartz by default, a JCA resource adapter would be needed and the MDB would be annotated with a reference to this.

Execution
EJBs are deployed in an EJB container, typically within an application server. The specification describes how an EJB interacts with its container and how client code interacts with the container/EJB combination. The EJB classes used by applications are included in the package. (The package is a service provider interface used only by EJB container implementations.)

Clients of EJBs do not instantiate those beans directly via Java's new operator, but instead have to obtain a reference via the EJB container. This reference is usually not a reference to the implementation bean itself, but to a proxy, which dynamically implements either the local or remote business interface that the client requested or a sub-type of the actual bean. The proxy can then be directly cast to the interface or bean respectively. A client is said to have a 'view' on the EJB, and the local interface, remote interface and bean sub-type itself respectively correspond to the local view, remote view and no-interface view.

This proxy is needed in order to give the EJB container the opportunity to transparently provide cross-cutting (AOP-like) services to a bean like transactions, security, interceptions, injections, and remoting. As an example, a client invokes a method on a proxy, which will first start a transaction with the help of the EJB container and then call the actual bean method. When the bean method returns, the proxy ends the transaction (i.e. by committing it or doing a rollback) and transfers control back to the client.

The EJB Container is responsible for ensuring the client code has sufficient access rights to an EJB. Security aspects can be declaratively applied to an EJB via annotations.

Transactions
EJB containers must support both container managed ACID transactions and bean managed transactions.

Container-managed transactions (CMT) are by default active for calls to session beans. That is, no explicit configuration is needed. This behavior may be declaratively tuned by the bean via annotations and if needed such configuration can later be overridden in the deployment descriptor. Tuning includes switching off transactions for the whole bean or specific methods, or requesting alternative strategies for transaction propagation and starting or joining a transaction. Such strategies mainly deal with what should happen if a transaction is or isn't already in progress at the time the bean is called. The following variations are supported:

Alternatively, the bean can also declare via an annotation that it wants to handle transactions programmatically via the JTA API. This mode of operation is called Bean Managed Transactions (BMT), since the bean itself handles the transaction instead of the container.

Events
JMS (Java Message Service) is used to send messages from beans to clients, to let clients receive asynchronous messages from these beans. MDBs can be used to receive messages from clients asynchronously using either a JMS Queue or a Topic.

Naming and directory services
As an alternative to injection, clients of an EJB can obtain a reference to the session bean's proxy object (the EJB stub) using Java Naming and Directory Interface (JNDI). This alternative can be used in cases where injection is not available, such as in non-managed code or standalone remote Java SE clients, or when it's necessary to programmatically determine which bean to obtain.

JNDI names for EJB session beans are assigned by the EJB container via the following scheme:

(entries in square brackets denote optional parts)

A single bean can be obtained by any name matching the above patterns, depending on the 'location' of the client. Clients in the same module as the required bean can use the module scope and larger scopes, clients in the same application as the required bean can use the app scope and higher, etc.

E.g. code running in the same module as the CustomerService bean (as given by the example shown earlier in this article) could use the following code to obtain a (local) reference to it:

Remoting/distributed execution
For communication with a client that's written in the Java programming language a session bean can expose a remote-view via an interface annotated with. This allows those beans to be called from clients in other JVMs which may be running on other systems (from the point of view of the EJB container, any code in another JVM is remote).

Stateless and Singleton session beans may also expose a "web service client view" for remote communication via WSDL and SOAP or plain XML. This follows the JAX-RPC and JAX-WS specifications. JAX-RPC support however is proposed for future removal. To support JAX-WS, the session bean is annotated with, and methods that are to be exposed remotely with.

Although the EJB specification does not mention exposure as RESTful web services in any way and has no explicit support for this form of communication, the JAX-RS specification does explicitly support EJB. Following the JAX-RS spec, Stateless and Singleton session beans can be declared as root resources via the  annotation and EJB business methods can be mapped to resource methods via the ,  ,   and   annotations. This however does not count as a "web service client view", which is used exclusively for JAX-WS and JAX-RPC.

Communication via web services is typical for clients not written in the Java programming language, but is also convenient for Java clients who have trouble reaching the EJB server via a firewall. Additionally, web service based communication can be used by Java clients to circumvent the arcane and ill-defined requirements for the so-called "client-libraries"; a set of jar files that a Java client must have on its class-path in order to communicate with the remote EJB server. These client-libraries potentially conflict with libraries the client may already have (for instance, if the client itself is also a full Java EE server) and such a conflict is deemed to be very hard or impossible to resolve.

Home interfaces and required business interface
With EJB 2.1 and earlier, each EJB had to provide a Java implementation class and two Java interfaces. The EJB container created instances of the Java implementation class to provide the EJB implementation. The Java interfaces were used by client code of the EJB.

Required deployment descriptor
With EJB 2.1 and earlier, the EJB specification required a deployment descriptor to be present. This was needed to implement a mechanism that allowed EJBs to be deployed in a consistent manner regardless of the specific EJB platform that was chosen. Information about how the bean should be deployed (such as the name of the home or remote interfaces, whether and how to store the bean in a database, etc.) had to be specified in the deployment descriptor.

The deployment descriptor is an XML document having an entry for each EJB to be deployed. This XML document specifies the following information for each EJB:
 * Name of the Home interface
 * Java class for the Bean (business object)
 * Java interface for the Home interface
 * Java interface for the business object
 * Persistent store (only for Entity Beans)
 * Security roles and permissions
 * Stateful or Stateless (for Session Beans)

Old EJB containers from many vendors required more deployment information than that in the EJB specification. They would require the additional information as separate XML files, or some other configuration file format. An EJB platform vendor generally provided their own tools that would read this deployment descriptor, and possibly generated a set of classes that would implement the now deprecated Home and Remote interfaces.

Since EJB 3.0 (JSR 220), the XML descriptor is replaced by Java annotations set in the Enterprise Bean implementation (at source level), although it is still possible to use an XML descriptor instead of (or in addition to) the annotations. If an XML descriptor and annotations are both applied to the same attribute within an Enterprise Bean, the XML definition overrides the corresponding source-level annotation, although some XML elements can also be additive (e.g., an activation-config-property in XML with a different name than already defined via an  annotation will be added instead of replacing all existing properties).

Container variations
Starting with EJB 3.1, the EJB specification defines two variants of the EJB container; a full version and a limited version. The limited version adheres to a proper subset of the specification called EJB 3.1 Lite and is part of Java EE 6's web profile (which is itself a subset of the full Java EE 6 specification).

EJB 3.1 Lite excludes support for the following features:
 * Remote interfaces
 * RMI-IIOP Interoperability
 * JAX-WS Web Service Endpoints
 * EJB Timer Service
 * Asynchronous session bean invocations
 * Message-driven beans

EJB 3.2 Lite excludes less features. Particularly it no longer excludes  and  /, but for   it does not support the "persistent" attribute that full EJB 3.2 does support. The complete excluded list for EJB 3.2 Lite is:
 * Remote interfaces
 * RMI-IIOP Interoperability
 * JAX-WS Web Service Endpoints
 * Persistent timers ("persistent" attribute on )
 * Message-driven beans

Version history
EJB 4.0, final release (2020-05-22)

Jakarta Enterprise Beans 4.0, as a part of Jakarta EE 9, was a tooling release that mainly moved API package names from the top level javax.ejb package to the top level jakarta.ejb package.

Other changes included removal of deprecated APIs that were pointless to move to the new top level package and the removal of features that depended on features that were removed from Java or elsewhere in Jakarta EE 9. The following APIs were removed:
 * methods relying on java.security.Identity which has been removed from the Java 14.
 * methods relying on Jakarta XML RPC to reflect the removal of XML RPC from the Jakarta EE 9 Platform.
 * deprecated EJBContext.getEnvironment method.
 * "Support for Distributed Interoperability" to reflect the removal of CORBA from Java 11 and the Jakarta EE 9 Platform.

Other minor changes include marking the Enterprise Beans 2.x API Group as "Optional" and making the Schedule annotation repeatable.

EJB 3.2.6, final release (2019-08-23)

Jakarta Enterprise Beans 3.2, as a part of Jakarta EE 8, and despite still using "EJB" abbreviation, this set of APIs has been officially renamed to "Jakarta Enterprise Beans" by the Eclipse Foundation so as not to tread on the Oracle "Java" trademark.

EJB 3.2, final release (2013-05-28)

JSR 345. Enterprise JavaBeans 3.2 was a relatively minor release that mainly contained specification clarifications and lifted some restrictions that were imposed by the spec but over time appeared to serve no real purpose. A few existing full EJB features were also demanded to be in EJB 3 lite and functionality that was proposed to be pruned in EJB 3.1 was indeed pruned (made optional).

The following features were added:
 * Passivation of a stateful session bean can be deactivated via attribute on  annotation (passivationCapable = false)
 * TimerService can retrieve all active timers in the same EJB module (could previously only retrieve timers for the bean in which the TimerService was called)
 * Lifecycle methods (e.g. ) can be transactional for stateful session beans using the existing   annotation
 * Autocloseable interface implemented by embeddable container

EJB 3.1, final release (2009-12-10)

JSR 318. The purpose of the Enterprise JavaBeans 3.1 specification is to further simplify the EJB architecture by reducing its complexity from the developer's point of view, while also adding new functionality in response to the needs of the community:
 * Local view without interface (No-interface view)
 * .war packaging of EJB components
 * EJB Lite: definition of a subset of EJB
 * Portable EJB Global JNDI Names
 * Singletons (Singleton Session Beans)
 * Application Initialization and Shutdown Events
 * EJB Timer Service Enhancements
 * Simple Asynchrony ( for session beans)

EJB 3.0, final release (2006-05-11)

JSR 220 - Major changes: This release made it much easier to write EJBs, using 'annotations' rather than the complex 'deployment descriptors' used in version 2.x. The use of home and remote interfaces and the ejb-jar.xml file were also no longer required in this release, having been replaced with a business interface and a bean that implements the interface.

EJB 2.1, final release (2003-11-24)

JSR 153 - Major changes:
 * Web service support (new): stateless session beans can be invoked over SOAP/HTTP. Also, an EJB can easily access a Web service using the new service reference.
 * EJB timer service (new): Event-based mechanism for invoking EJBs at specific times.
 * Message-driven beans accepts messages from sources other than JMS.
 * Message destinations (the same idea as EJB references, resource references, etc.) has been added.
 * EJB query language (EJB-QL) additions: ORDER BY, AVG, MIN, MAX, SUM, COUNT, and MOD.
 * XML schema is used to specify deployment descriptors, replaces DTDs

EJB 2.0, final release (2001-08-22)

JSR 19 - Major changes: Overall goals:
 * The standard component architecture for building distributed object-oriented business applications in Java.
 * Make it possible to build distributed applications by combining components developed using tools from different vendors.
 * Make it easy to write (enterprise) applications: Application developers will not have to understand low-level transaction and state management details, multi-threading, connection pooling, and other complex low-level APIs.
 * Will follow the "Write Once, Run Anywhere" philosophy of Java. An enterprise Bean can be developed once, and then deployed on multiple platforms without recompilation or source code modification.
 * Address the development, deployment, and runtime aspects of an enterprise application’s life cycle.
 * Define the contracts that enable tools from multiple vendors to develop and deploy components that can interoperate at runtime.
 * Be compatible with existing server platforms. Vendors will be able to extend their existing products to support EJBs.
 * Be compatible with other Java APIs.
 * Provide interoperability between enterprise Beans and Java EE components as well as non-Java programming language applications.
 * Be compatible with the CORBA protocols (RMI-IIOP).

EJB 1.1, final release (1999-12-17)

Major changes:
 * XML deployment descriptors
 * Default JNDI contexts
 * RMI over IIOP
 * Security - role driven, not method driven
 * Entity Bean support - mandatory, not optional

Goals for Release 1.1:
 * Provide better support for application assembly and deployment.
 * Specify in greater detail the responsibilities of the individual EJB roles.

EJB 1.0 (1998-03-24)

Announced at JavaOne 1998, Sun's third Java developers conference (March 24 through 27) Goals for Release 1.0:
 * Defined the distinct "EJB Roles" that are assumed by the component architecture.
 * Defined the client view of enterprise Beans.
 * Defined the enterprise Bean developer’s view.
 * Defined the responsibilities of an EJB Container provider and server provider; together these make up a system that supports the deployment and execution of enterprise Beans.

title: Jakarta Enterprise Beans


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J. Michael Straczynski

Joseph Michael Straczynski (born July 17, 1954) is an American filmmaker and comic book writer. He is the founder of Synthetic Worlds Ltd. and Studio JMS and is best known as the creator of the science fiction television series Babylon 5 (1993–1998) and its spinoff Crusade (1999), as well as the series Jeremiah (2002–2004) and Sense8 (2015–2018). He is the executor of the estate of Harlan Ellison.

Straczynski wrote the psychological drama film Changeling (2008) and was co-writer on the martial arts thriller Ninja Assassin (2009), was one of the key writers for (and had a cameo in) Marvel's Thor (2011), as well as the horror film Underworld: Awakening (2012), and the apocalyptic horror film World War Z (2013). From 2001 to 2007, Straczynski wrote Marvel Comics' The Amazing Spider-Man, followed by runs on Thor and Fantastic Four. He is the author of the Superman: Earth One trilogy of graphic novels, and he has written Superman, Wonder Woman, and Before Watchmen for DC Comics. Straczynski is the creator and writer of several original comic book series such as Rising Stars, Midnight Nation, Dream Police, and Ten Grand through Joe's Comics.

A prolific writer across a variety of media and former journalist, Straczynski is the author of the autobiography Becoming Superman (2019) for HarperVoyager, the novel Together We Will Go (2021) for Simon & Schuster, and Becoming a Writer, Staying a Writer (2021) for Benbella Books. In 2020 he was named Head of the Creative Council for the comics publishing company Artists, Writers and Artisans.

Straczynski is a long-time participant in Usenet and other early computer networks, interacting with fans through various online forums (including GEnie, CompuServe, and America Online) since 1984. He is credited as being the first TV producer to directly engage with fans on the Internet and to allow viewer viewpoints to influence the look and feel of his show (see Babylon 5's use of the Internet). Two prominent areas where he had a presence were GEnie and the newsgroup rec.arts.sf.tv.babylon5.moderated.

Early and personal life
Straczynski was born in Paterson, New Jersey, and is the son of Charles Straczynski, a manual laborer, and Evelyn Straczynski (née Pate). He was raised in Newark, New Jersey; Kankakee, Illinois; Dallas, Texas; Chula Vista, California, where he graduated from high school; and San Diego, California. Straczynski's family religion was Catholic although he is an atheist. He has Polish ancestry and his grandparents lived in the area which today belongs to Belarus and fled to the United States from the Russian Revolution; his father was born in the United States and has lived in Poland, Germany and Russia.

Straczynski is a graduate of Southwestern College and San Diego State University (SDSU), having earned an AA and later an honorary degree from Southwestern, where he was mentored by Professor Bill Virchis, and a BA with a double major in psychology and sociology (with minors in philosophy and literature) from San Diego State. While at SDSU, he wrote for the student newspaper, The Daily Aztec.

Straczynski met Kathryn M. Drennan while they were at SDSU. They moved to Los Angeles in 1981 (where he still resides), married in 1983, separated in 1999, and they were divorced in 2001. Sometime after his separation from Drennan, Straczynski entered into a relationship with Patricia Tallman, whom he had met when she was acting in his 1990s series Babylon 5. She served as CEO and executive producer of Studio JMS in partnership with him; both their relationship and partnership ended in 2013.

Straczynski has Asperger syndrome. Straczynski had a voluntary vasectomy when he turned 21, and wrote about the experience in the January 28, 1983 edition of the Los Angeles Reader.

Early work
Straczynski began writing plays, having several produced at Southwestern College and San Diego State University before publishing his adaptation of Snow White with Performance Publishing. Several other plays were produced around San Diego, including The Apprenticeship for the Marquis Public Theater. During the late 1970s, Straczynski became the on-air entertainment reviewer for KSDO-FM and wrote several radio plays before being hired as a scriptwriter for the radio drama Alien Worlds. He produced his first television project in San Diego, Marty Sprinkle for KPBS-TV as well as worked on the XETV-TV project Disasterpiece Theatre. He worked as a journalist for the Los Angeles Times as a special San Diego correspondent and worked for San Diego Magazine and The San Diego Reader, and wrote for the Los Angeles Herald-Examiner, the Los Angeles Reader, TV-Cable Week, and 'People' magazine. Straczynski wrote The Complete Book of Scriptwriting for Writer's Digest. Published in 1982, the book is often used as a text in introductory screenwriting courses, and is in its third edition.

He spent five years from 1987 to 1992 co-hosting the Hour 25 radio talk show on KPFK-FM Los Angeles with Larry DiTillio. During his tenure, he interviewed John Carpenter, Neil Gaiman, Ray Bradbury, Harlan Ellison and other writers, producers, actors and directors. In 2000, Straczynski returned to radio drama with The City of Dreams for scifi.com. Straczynski is the author of three horror novels—Demon Night, Othersyde, and Tribulations—and nearly twenty short stories, many of which are collected in two compilations—Tales from the New Twilight Zone and Straczynski Unplugged.

Work in animation
Straczynski was a fan of the cartoon He-Man and the Masters of the Universe. He wrote a spec script in 1984 and sent it directly to Filmation. Filmation purchased his script and several others, and hired him on staff. During this time he became friends with Larry DiTillio, and when Filmation produced the He-Man spinoff She-Ra: Princess of Power, they worked as story editors on the show. However, when Filmation refused to give them credit on-screen, both left, finding work with DIC on Jayce and the Wheeled Warriors.

Straczynski and DiTillio worked to create an animated version of Elfquest, but that project fell through when CBS attempted to retool the show to appeal to younger audiences.

While working on Jayce, Straczynski was hired to come aboard the Len Janson and Chuck Menville project to adapt the movie Ghostbusters to an animated version called The Real Ghostbusters. When Janson and Menville learned that there was not only a 13-episode order but a 65-episode syndication order as well, they decided that the workload was too much and that they would only work on their own scripts. DIC head Jean Chalopin asked Straczynski to take on the task of story editing the entire 78-episode block as well as writing his own scripts. After the show's successful first season, consultants were brought in to make suggestions for the show, including changing Janine to a more maternal character, giving every character a particular "job" (Peter is the funny one, Egon is the smart one, and Winston, the only black character, was to be the driver), and to add kids into the show. Straczynski left at this point, Janson and Menville resuming the story editing job for the second network season. Straczynski then began development on a show called Spiral Zone but left after only one script, taking his name off the series, because management drastically altered his conception of show. substituting the pseudonym "Fettes Grey" (derived from the names of the grave robbers in The Body Snatcher).

Straczynski wrote for CBS Storybreak, writing an adaptation of Evelyn Sibley Lampman's The Shy Stegosaurus of Cricket Creek.

Live action and network shows
After leaving animation, Straczynski freelanced for The Twilight Zone writing an episode entitled "What Are Friends For" and, for Shelley Duvall's Nightmare Classics, adapting The Strange Case of Dr. Jekyll and Mr. Hyde, which was nominated for a Writer's Guild Award.

Straczynski was offered the position of story editor on the syndicated live-action science fiction series Captain Power and the Soldiers of the Future. Straczynski constructed a season long arc with lasting character changes and wrote a third of the scripts himself. After one season, the toy company Mattel demanded more input into the show, causing Straczynski to quit. He recommended DiTillio to take over the job as story editor for a second season, but the toy company financing fell through and that season was never produced.

Soon after, the 1988 Writers Guild of America strike began. Straczynski met Harlan Ellison during this time and later became friends with him. Straczynski is an executor of Ellison's collected works.

After the strike ended, the producers of the new Twilight Zone needed to create more episodes to be able to sell the series into syndication with a complete 65-episode package. They hired Straczynski as executive story editor to fill in the remaining number of needed episodes. Straczynski wrote many of the scripts himself. In addition, one episode, "Crazy as a Soup Sandwich", was written by Ellison.

After leaving Twilight Zone, his agent of the time asked him to pitch for the show Jake and the Fatman. Initially wary, Straczynski finally did and was hired on as an executive story consultant under Jeri Taylor and David Moessinger. When Taylor and Moessinger left the show, Straczynski left too as an act of solidarity.

When Moessinger was hired as executive producer for Murder, She Wrote, he offered Straczynski a job as co-producer. Straczynski joined Murder, She Wrote for two seasons and wrote seven produced episodes. Moessinger and Straczynski moved the protagonist, Jessica Fletcher, from the sleepy Maine town of Cabot Cove to New York City to revitalize the show. The move effectively brought the show back into the top ten from the mid-thirties where it had fallen. Straczynski made Jessica an instructor in writing and criminology, and he emphasized her role as a working writer, with all the deadlines and problems involved in that profession.

Straczynski wrote one episode of Walker, Texas Ranger for Moessinger between the pilot episode for Babylon 5 and the start of its first season.

Straczynski wrote an adaptation of Robert Louis Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde for the Showtime network, which was nominated for a Writers Guild of America award, and a Murder, She Wrote movie, Murder, She Wrote: A Story to Die For, which he produced.

Babylon 5 and Crusade
In late 1991, Warner Bros. contracted with Straczynski and Doug Netter as partners to produce Babylon 5 as the flagship program for the new Prime Time Entertainment Network.

Straczynski and Netter hired many of the people from Captain Power, as well as hiring Ellison as a consultant and DiTillio as a story editor. Babylon 5 won two Emmy Awards, back-to-back Hugo Awards, and dozens of other awards. Straczynski wrote 92 of the 110 episodes, as well as the pilot and five television movies. The show is a character-driven space opera and features an intentional emphasis on realism in its portrayal of space operations. It pioneered extensive use of CGI for its special effects. Babylon 5 was produced and broadcast for five seasons completing Stracynski's planned story arc. Its sequel, Crusade, was produced for the TNT Network, however it ended with only 13 episodes. Production was halted before the first episode aired.

He wrote the outlines for nine of the canonical Babylon 5 novels, supervised the three produced Babylon 5 telefilm novelizations (In the Beginning, Thirdspace, and A Call to Arms), and is the author of four Babylon 5 short stories published in magazines, not yet reprinted.

In 2005, Straczynski began publishing his Babylon 5 scripts. This process ended in June 2008, with the scripts no longer being available from the end of July of that year. His scripts for the television movies were published for a limited time in January 2009.

Straczynski wrote and produced the pilot Babylon 5: The Legend of the Rangers, a pilot for the SciFi Network, and wrote, directed and produced Babylon 5: The Lost Tales as a two-hour direct-to-DVD movie.

Joe's Comics
Straczynski has long been a comic fan and began writing comics in the late 1980s. His work in comics includes the adaptations of Captain Power and the Soldiers of the Future, The Twilight Zone, Star Trek and Babylon 5. In 1999 he created Rising Stars for Top Cow/Image Comics. Eventually he worked mostly under his own imprint – Joe's Comics – for which he wrote the Midnight Nation miniseries and the illustrated fantasy parable Delicate Creatures.

Marvel Comics
Marvel Comics signed him to an exclusive contract, beginning with a run on The Amazing Spider-Man, from 2001 to 2007. He took over the series with Volume 2 issue #30 (cover dated June 2001). Straczynski and artist John Romita Jr. crafted an acclaimed story for The Amazing Spider-Man #36 (Dec. 2001) in response to the September 11 attacks. He wrote or co-wrote several major Spider-Man story arcs including "Spider-Man: The Other", "Back in Black", and the infamous "One More Day". He later wrote several other Marvel titles including Supreme Power, Strange, Fantastic Four, Thor, and mini-series featuring the Silver Surfer and a "What If" scenario, Bullet Points.

Jeremiah
Straczynski ran Jeremiah, loosely based on the Belgian post-apocalyptic comic Jeremiah, from 2002–2004. Straczynski ran the series for two seasons but was frustrated with the conflicting directions that MGM and Showtime wanted from the show, and even used the pseudonym "Fettes Grey" for the first time since Spiral Zone on one of the scripts. In the second season, Straczynski decided to leave the show if things did not improve, and the show ended after two seasons.

Changeling
Straczynski wrote Changeling, a psychological drama film based partly on the "Wineville Chicken Coop" kidnapping and murder case in Los Angeles, California. Directed by Clint Eastwood, produced by Ron Howard, and starring Angelina Jolie, the film premiered in 2008 and subsequently received eight nominations for the BAFTA Award, including a nomination for Best Original Screenplay. The first draft script was written in eleven days, after Straczynski figured out "how to tell" the story, which ended up being the shooting draft, after Eastwood declined to make any changes. It was optioned immediately by Howard, who at first intended to direct the film but later stepped down after scheduling conflicts.

At first, Straczynski expressed disbelief at the story, but spent a year researching the case, compiling over six thousands pages of documentation. Straczynski claimed that 95% of the script's content came from the historical record, and went through the script with Universal Studios's legal department, providing attribution for every scene so the film would be described as "a true story" rather than "based on" one. On how his journalistic background helped him write the film, Straczynski stated:

"It was hugely important. Usually, when you're asked to tell a true story in film, there's already an article or something where the legwork's been done. In this case, there was nothing available. It was all primary research—City Hall archives, county courthouse archives, criminal records, hospital records. I just sifted through stuff, often spending a whole day paging through records just to find one reference."

Feature screenwriter
Straczynski announced on February 23, 2007, that he had been hired to write the feature film adaptation of Max Brooks's novel World War Z for Paramount Pictures and production company Plan B Entertainment, taking screen story credit on the finished film.

In 2008, Straczynski wrote a draft of Ninja Assassin for Joel Silver, which he completed in just 53 hours. The film was produced by The Wachowskis and released on November 25, 2009.

Straczynski is credited as "story writer" along with Mark Protosevich for the 2011 film, Thor. He makes a cameo appearance in the film, his first appearance in a movie and his second appearance as an actor (the first being "Sleeping in Light", the final episode of Babylon 5). Straczynski was part of the writers room (along with Terry Rossio, Patrick McKay, J. D. Payne, Lindsey Beer, Cat Vasko, T.S. Nowlin, and Jack Paglen) to develop Godzilla vs. Kong, though was uncredited on the final script.

DC Comics
When his exclusive contract with Marvel ended, he was announced as the writer for a run on The Brave and the Bold for DC Comics. He collaborated with artist Shane Davis on an out-of-continuity original graphic novel starring Superman titled Superman: Earth One. The story features a young Superman and focus on his decision about the role he wants to assume in life. On March 8, 2010, it was announced he would be taking over writing duties for the monthly Superman title with a story arc entitled "Grounded", and the Wonder Woman title, beginning with issues 701 and 601 respectively. Less than a year later he was asked by DC to step away from both titles in order to concentrate on the second volume of Superman: Earth One and handed them over to Chris Roberson and Phil Hester to finish his Superman and Wonder Woman stories respectively. In 2012, Straczynski wrote Before Watchmen: Dr. Manhattan drawn by Adam Hughes and Before Watchmen: Nite Owl drawn by Andy Kubert and Joe Kubert. A second volume of Superman: Earth One was released later that same year.

At the San Diego Comic-Con in 2015, DC Comics announced The Flash: Earth One, a new graphic novel of its Earth One line to be written by Straczynski, set to be published in 2016. As of 2023, it has still not been published.

Studio JMS
In July 2012, J. Michael Straczynski announced the launch of Studio JMS to produce TV series, movies, comics and, in the future, games and web series. On March 27, 2013, Netflix announced they would produce the show Sense8 with Studio JMS and The Wachowskis, which aired on June 5, 2015, and earned a season 2 announcement by August 10, 2015.

Joe's Comics revival
The Joe's Comics line was revived at Image Comics in 2013 with the launch of Ten Grand drawn by Ben Templesmith and Sidekick drawn by Tom Mandrake.

Dynamite Entertainment announced in July 2013 a new 12 issue The Twilight Zone comic book series penned by Straczynski. The series ran for its projected 12 issues, from December 2013 to February 2015, with art by Guiu Vilanova. Straczynski was announced as the writer of Terminator Salvation: The Final Battle, a 12 issue comic book series from Dark Horse Comics, along with artist Pete Woods.

Sense8
Sense8, a science fiction television series created by Straczynski and The Wachowskis was ordered straight-to-series by Netflix in March 2013. Sense8's first season debuted in June 2015 on Netflix, from Studio JMS and Georgeville Television. Straczynski executive produced and co-wrote all 12 episodes of the first season with fellow creators, executive producers, and directors Lilly and Lana Wachowski. In August 2015, Netflix renewed Sense8 for a second season.

Artists Writers and Artisans
In 2020, Straczynski was named head of the Creative Council for the new comics publishing company AWA, where he was responsible for creating the shared universe used by many of its writers.

Following the publication of his autobiography Becoming Superman in 2019 from HarperVoyager, the novel Together We Will Go was published in 2021 by Simon & Schuster's Scout Press, and Becoming A Writer, Staying A Writer was published in 2021 by Benbella Books.

Return to Babylon 5
In 2022, Straczynski announced that a reboot of his series Babylon 5 was in the works at The CW, with the pilot script written by him. Following a buy-out of the CW by NextStar and strike action by the WGA, work on the project was stalled.

In 2023, it was announced by Straczynski that a fully animated Babylon 5 feature film, Babylon 5: The Road Home, had been produced in secret and was scheduled for release in the summer of that year, reunited the surviving members of the original cast. It was released in August 2023.

Return to Marvel Comics
Across 2021 and 2022, Straczynski contributed short stories to several anthology and milestone editions of comics published by Marvel Comics, this led to him writing a mystery six issue event mini-series for the publisher. In June 2023, it was announced Straczynski would write the next volume of Captain America, beginning in September of that year.

Unrealized projects
In 2004, Straczynski was approached by Paramount Studios to become a producer of the Star Trek: Enterprise series. He declined, believing that he would not be allowed to take the show in the direction he felt it should go. He did write a treatment for a new Star Trek series with colleague Bryce Zabel.

After both Babylon 5 and Jeremiah ended, Straczynski transitioned to working as a feature film screenwriter. In 2006, he was hired to write a feature film based on the story of King David for Universal by producers Erwin Stoff and Akiva Goldsman. In June 2007, it was announced that Straczynski had written a feature screenplay for the Silver Surfer movie for Fox, the production of which would depend on the success of the Fantastic Four: Rise of the Silver Surfer. Additionally, he has written a script for Tom Hanks' Playtone Productions and Universal Pictures called They Marched into Sunlight based upon the Pulitzer nominated novel of the same name and an outline by Paul Greengrass, for Greengrass to direct, should it get a greenlight.

In June 2008, Daily Variety named Straczynski one of the top Ten Screenwriters to Watch. They announced Straczynski was writing Lensman for Ron Howard (to whom he had sold a screenplay entitled The Flickering Light), that he was selling another spec, Proving Ground, to Tom Cruise and United Artists. In October 2008, it was announced that Straczynski was engaged to pen a remake of the science fiction classic Forbidden Planet. In the fall of 2009, it was reported that Straczynski was writing a movie titled Shattered Union for Jerry Bruckheimer and Disney. The screenplay, based on the video game of that name, concerns itself with a present-day American civil war.

In October 2012, Valiant Entertainment announced a live-action feature film adaptation on its comic book series Shadowman, written and executive produced by Straczynski. The Flickering Light, Straczynski's directorial debut, was announced in February 2013, with the World War II drama set to be written and produced by Straczynski through his Studio JMS. Straczynski and Studio JMS optioned Harlan Ellison's short story "Repent, Harlequin!" Said the Ticktockman, who granted the option only after reading a finished screenplay written by Straczynski.

On San Diego Comic-Con 2014, it was announced that Straczynski and Graphic India would team up with Chernin Entertainment to produce a feature film adaptation of his upcoming graphic novel Titans, to be written and produced by Straczynski, through Studio JMS.

Straczynski was hired to adapt Red Mars for Spike TV, based on the Kim Stanley Robinson novels, with Vince Gerardis as producer. In December 2015, Spike TV gave a 10-episode straight-to-series order to Red Mars, set to premiere in January 2017, with Straczynski serving as writer, executive producer, and showrunner through Studio JMS, and production set to begin in Summer 2016. On March 25, 2016 Deadline reported that Straczynski had left his position as showrunner with Peter Noah replacing him but he too left due to creative differences with Spike. Spike has put the series on hold for further development.

On July 30, 2021, Straczynski expressed an interest in becoming showrunner of the BBC Television series Doctor Who, following the departure of Chris Chibnall, confirming his representatives had been contacting the BBC. On August 19, Straczynski confirmed contact had been made with the BBC, but that the organization had already begun their own selection process and were not seeking new candidates. On September 24, 2021, the BBC confirmed former showrunner Russell T Davies would return, which Straczynski commended.

Selected accolades
An asteroid, discovered in 1992 at the Kitt Peak National Observatory, was honorarily named 8379 Straczynski.

Joe's Comics

 * Rising Stars #1–24 (1999–2005)
 * Midnight Nation #1–12 (2000–2002)

Marvel Comics

 * The Amazing Spider-Man vol. 2 #30–58, vol. 1 #500–545 (2001–2007)
 * Supreme Power #1–18 (Marvel MAX, 2003–2006)
 * Silver Surfer: Requiem #1–4 (Marvel Knights, 2007)
 * Thor vol. 3 #1–12, vol. 1 #600–603, Giant-Size Finale #1 (2007–2009)
 * Thor vol. 6 #24 (2022)
 * Captain America vol. 11

DC Comics

 * Superman: Earth One Volume 1–3 (2010–2015)
 * Before Watchmen:
 * Nite Owl #1–4 (2012)
 * Dr. Manhattan #1–4 (2012)

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

title: J. Michael Straczynski


text:
Sonoluminescence

Sonoluminescence is the emission of light from imploding bubbles in a liquid when excited by sound.

Sonoluminescence was first discovered in 1934 at the University of Cologne. It occurs when a sound wave of sufficient intensity induces a gaseous cavity within a liquid to collapse quickly, emitting a burst of light. The phenomenon can be observed in stable single-bubble sonoluminescence (SBSL) and multi-bubble sonoluminescence (MBSL). In 1960, Peter Jarman proposed that sonoluminescence is thermal in origin and might arise from microshocks within collapsing cavities. Later experiments revealed that the temperature inside the bubble during SBSL could reach up to 12000 K. The exact mechanism behind sonoluminescence remains unknown, with various hypotheses including hotspot, bremsstrahlung, and collision-induced radiation. Some researchers have even speculated that temperatures in sonoluminescing systems could reach millions of kelvins, potentially causing thermonuclear fusion; this idea, however, has been met with skepticism by other researchers. The phenomenon has also been observed in nature, with the pistol shrimp being the first known instance of an animal producing light through sonoluminescence.

History
The sonoluminescence effect was first discovered at the University of Cologne in 1934 as a result of work on sonar. Hermann Frenzel and H. Schultes put an ultrasound transducer in a tank of photographic developer fluid. They hoped to speed up the development process. Instead, they noticed tiny dots on the film after developing and realized that the bubbles in the fluid were emitting light with the ultrasound turned on. It was too difficult to analyze the effect in early experiments because of the complex environment of a large number of short-lived bubbles. This phenomenon is now referred to as multi-bubble sonoluminescence (MBSL).

In 1960, Peter Jarman from Imperial College of London proposed the most reliable theory of sonoluminescence phenomenon. He concluded that sonoluminescence is basically thermal in origin and that it might possibly arise from microshocks with the collapsing cavities.

In 1990, an experimental advance was reported by Gaitan and Crum, who produced stable single-bubble sonoluminescence (SBSL). In SBSL, a single bubble trapped in an acoustic standing wave emits a pulse of light with each compression of the bubble within the standing wave. This technique allowed a more systematic study of the phenomenon because it isolated the complex effects into one stable, predictable bubble. It was realized that the temperature inside the bubble was hot enough to melt steel, as seen in an experiment done in 2012; the temperature inside the bubble as it collapsed reached about 12000 K. Interest in sonoluminescence was renewed when an inner temperature of such a bubble well above 1 MK was postulated. This temperature is thus far not conclusively proven; rather, recent experiments indicate temperatures around 20000 K.

Properties

Sonoluminescence can occur when a sound wave of sufficient intensity induces a gaseous cavity within a liquid to collapse quickly. This cavity may take the form of a preexisting bubble or may be generated through a process known as cavitation. Sonoluminescence in the laboratory can be made to be stable so that a single bubble will expand and collapse over and over again in a periodic fashion, emitting a burst of light each time it collapses. For this to occur, a standing acoustic wave is set up within a liquid, and the bubble will sit at a pressure antinode of the standing wave. The frequencies of resonance depend on the shape and size of the container in which the bubble is contained.

Some facts about sonoluminescence:
 * The light that flashes from the bubbles last between 35 and a few hundred picoseconds long, with peak intensities of the order of 1 –.
 * The bubbles are very small when they emit light—about 1 μm in diameter—depending on the ambient fluid (e.g., water) and the gas content of the bubble (e.g., atmospheric air).
 * SBSL pulses can have very stable periods and positions. In fact, the frequency of light flashes can be more stable than the rated frequency stability of the oscillator making the sound waves driving them. The stability analyses of the bubble, however, show that the bubble itself undergoes significant geometric instabilities due to, for example, the Bjerknes forces and Rayleigh–Taylor instabilities.
 * The addition of a small amount of noble gas (such as helium, argon, or xenon) to the gas in the bubble increases the intensity of the emitted light.

Spectral measurements have given bubble temperatures in the range from 2300 to 5100 K, the exact temperatures depending on experimental conditions including the composition of the liquid and gas. Detection of very high bubble temperatures by spectral methods is limited due to the opacity of liquids to short wavelength light characteristic of very high temperatures.

A study describes a method of determining temperatures based on the formation of plasmas. Using argon bubbles in sulfuric acid, the data shows the presence of ionized molecular oxygen, sulfur monoxide, and atomic argon populating high-energy excited states, which confirms a hypothesis that the bubbles have a hot plasma core. The ionization and excitation energy of dioxygenyl cations, which they observed, is 18 eV. From this observation, they conclude the core temperatures reach at least 20000 K —hotter than the surface of the Sun.

Rayleigh–Plesset equation

The dynamics of the motion of the bubble is characterized to a first approximation by the Rayleigh–Plesset equation (named after Lord Rayleigh and Milton Plesset):

 * $$R\ddot{R} + \frac{3}{2}\dot{R}^{2} = \frac{1}{\rho}\left(P_\infty(t) - P_0(t) - 4\mu\frac{\dot{R}}{R} - \frac{2\gamma}{R}\right)$$

This is an approximate equation that is derived from the Navier–Stokes equations (written in spherical coordinate system) and describes the motion of the radius of the bubble R as a function of time t. Here, μ is the viscosity, $$P_\infty(t)$$ is the external pressure infinitely far from the bubble, $$P_0(t)$$ is the internal pressure of the bubble, $$\rho$$ is the liquid density, and γ is the surface tension. The over-dots represent time derivatives. This equation, though approximate, has been shown to give good estimates on the motion of the bubble under the acoustically driven field except during the final stages of collapse. Both simulation and experimental measurement show that during the critical final stages of collapse, the bubble wall velocity exceeds the speed of sound of the gas inside the bubble. Thus a more detailed analysis of the bubble's motion is needed beyond Rayleigh–Plesset to explore the additional energy focusing that an internally formed shock wave might produce. In the static case, the Rayleigh-Plesset equation simplifies, yielding the Young–Laplace equation.

Mechanism of phenomenons
The mechanism of the phenomenon of sonoluminescence is unknown. Hypotheses include: hotspot, bremsstrahlung radiation, collision-induced radiation and corona discharges, nonclassical light, proton tunneling, electrodynamic jets and fractoluminescent jets (now largely discredited due to contrary experimental evidence).

In 2002, M. Brenner, S. Hilgenfeldt, and D. Lohse published a 60-page review that contains a detailed explanation of the mechanism. An important factor is that the bubble contains mainly inert noble gas such as argon or xenon (air contains about 1% argon, and the amount dissolved in water is too great; for sonoluminescence to occur, the concentration must be reduced to 20–40% of its equilibrium value) and varying amounts of water vapor. Chemical reactions cause nitrogen and oxygen to be removed from the bubble after about one hundred expansion-collapse cycles. The bubble will then begin to emit light. The light emission of highly compressed noble gas is exploited technologically in the argon flash devices.

During bubble collapse, the inertia of the surrounding water causes high pressure and high temperature, reaching around 10,000 kelvins in the interior of the bubble, causing the ionization of a small fraction of the noble gas present. The amount ionized is small enough for the bubble to remain transparent, allowing volume emission; surface emission would produce more intense light of longer duration, dependent on wavelength, contradicting experimental results. Electrons from ionized atoms interact mainly with neutral atoms, causing thermal bremsstrahlung radiation. As the wave hits a low energy trough, the pressure drops, allowing electrons to recombine with atoms and light emission to cease due to this lack of free electrons. This makes for a 160-picosecond light pulse for argon (even a small drop in temperature causes a large drop in ionization, due to the large ionization energy relative to photon energy). This description is simplified from the literature above, which details various steps of differing duration from 15 microseconds (expansion) to 100 picoseconds (emission).

Computations based on the theory presented in the review produce radiation parameters (intensity and duration time versus wavelength) that match experimental results with errors no larger than expected due to some simplifications (e.g., assuming a uniform temperature in the entire bubble), so it seems the phenomenon of sonoluminescence is at least roughly explained, although some details of the process remain obscure.

Any discussion of sonoluminescence must include a detailed analysis of metastability. Sonoluminescence in this respect is what is physically termed a bounded phenomenon meaning that the sonoluminescence exists in a bounded region of parameter space for the bubble; a coupled magnetic field being one such parameter. The magnetic aspects of sonoluminescence are very well documented.

Quantum explanations
An unusually exotic hypothesis of sonoluminescence, which has received much popular attention, is the Casimir energy hypothesis suggested by noted physicist Julian Schwinger and more thoroughly considered in a paper by Claudia Eberlein of the University of Sussex. Eberlein's paper suggests that the light in sonoluminescence is generated by the vacuum within the bubble in a process similar to Hawking radiation, the radiation generated at the event horizon of black holes. According to this vacuum energy explanation, since quantum theory holds that vacuum contains virtual particles, the rapidly moving interface between water and gas converts virtual photons into real photons. This is related to the Unruh effect or the Casimir effect. The argument has been made that sonoluminescence releases too large an amount of energy and releases the energy on too short a time scale to be consistent with the vacuum energy explanation, although other credible sources argue the vacuum energy explanation might yet prove to be correct.

Nuclear reactions
Some have argued that the Rayleigh–Plesset equation described above is unreliable for predicting bubble temperatures and that actual temperatures in sonoluminescing systems can be far higher than 20,000 kelvins. Some research claims to have measured temperatures as high as 100,000 kelvins and speculates temperatures could reach into the millions of kelvins. Temperatures this high could cause thermonuclear fusion. This possibility is sometimes referred to as bubble fusion and is likened to the implosion design used in the fusion component of thermonuclear weapons.

Experiments in 2002 and 2005 by R. P. Taleyarkhan using deuterated acetone showed measurements of tritium and neutron output consistent with fusion. However, the papers were considered low quality and there were doubts cast by a report about the author's scientific misconduct. This made the report lose credibility among the scientific community.

On January 27, 2006, researchers at Rensselaer Polytechnic Institute claimed to have produced fusion in sonoluminescence experiments.

Biological sonoluminescence
Pistol shrimp (also called snapping shrimp) produce a type of cavitation luminescence from a collapsing bubble caused by quickly snapping its claw. The animal snaps a specialized claw shut to create a cavitation bubble that generates acoustic pressures of up to 80 kPa at a distance of 4 cm from the claw. As it extends out from the claw, the bubble reaches speeds of 60 miles per hour (97 km/h) and releases a sound reaching 218 decibels. The pressure is strong enough to kill small fish. The light produced is of lower intensity than the light produced by typical sonoluminescence and is not visible to the naked eye. The light and heat produced by the bubble may have no direct significance, as it is the shockwave produced by the rapidly collapsing bubble which these shrimp use to stun or kill prey. However, it is the first known instance of an animal producing light by this effect and was whimsically dubbed "shrimpoluminescence" upon its discovery in 2001. It has subsequently been discovered that another group of crustaceans, the mantis shrimp, contains species whose club-like forelimbs can strike so quickly and with such force as to induce sonoluminescent cavitation bubbles upon impact.

A mechanical device with 3D printed snapper claw at five times the actual size was also reported to emit light in a similar fashion, this bioinspired design was based on the snapping shrimp snapper claw molt shed from an Alpheus formosus, the striped snapping shrimp.

title: Sonoluminescence


text:
University of Cologne

The University of Cologne (Universität zu Köln) is a university in Cologne, Germany. It was established in the year 1388, the sixth university to be established in Central Europe. It closed in 1798 before being re-established in 1919. It is now one of the largest universities in Germany with more than 50,000 students. The University of Cologne is a member of the German U15 association of major research-intensive universities and was a university of excellence as part of the German Universities Excellence Initiative from 2012 to 2019. It is constantly ranked among top 20 German universities in the world rankings.

University of Cologne has 4 Clusters of Excellence; CECAD Cluster of Excellence for Aging Research, Cluster of Excellence ECONtribute: Markets & Public Policy, CEPLAS Cluster of Excellence for Plant Sciences and Cluster of Excellence Matter and Light for Quantum Information (ML4Q). As of 2022, among its notable alumni, faculty and researchers are 4 Nobel Laureates, 11 Gottfried Wilhelm Leibniz Prize winners, 7 Humboldt Professorship winners, 2 Humboldt Research Awards winners and 1 Rhodes Scholar.

1388–1798
The university of Cologne was established in 1388 as the fourth university in the Holy Roman Empire, after the Charles University of Prague (1348), the University of Vienna (1365) and the Ruprecht Karl University of Heidelberg (1386). The charter was signed by Pope Urban VI. The university began teaching on 6 January 1389, and operated for several hundred years.

In 1798, the university was abolished by the French First Republic, who had invaded Cologne in 1794, because under the new French constitution, many universities were abolished all over France. The last rector Ferdinand Franz Wallraf was able to preserve the university's Great Seal, now once more in use.

1919–today
In 1919, the Prussian government endorsed a decision by the Cologne City Council to re-establish the university. This was considered to be a replacement for the loss of the University of Strasbourg on the west bank of the Rhine, which contemporaneously reverted to France with the rest of Alsace. On 29 May 1919, the Cologne Mayor Konrad Adenauer signed the charter of the modern university.

At that point, the new university was located in Neustadt-Süd, but relocated to its current campus in Lindenthal on 2 November 1934. The old premises are now being used for the Cologne University of Applied Sciences.

Initially, the university was composed of the Faculty of Business, Economics and Social Sciences (successor to the Institutes of Commerce and of Communal and Social Administration) and the Faculty of Medicine (successor to the Academy of Medicine). In 1920, the Faculty of Law and the Faculty of Arts were added, from which latter the School of Mathematics and Natural Sciences was split off in 1955 to form a separate Faculty. In 1980, the two Cologne departments of the Rhineland School of Education were attached to the university as the Faculties of Education and of Special Education. In 1988, the university became a founding member of the Community of European Management Schools and International Companies (CEMS), today's Global Alliance in Management Education.

The university is a leader in the area of economics and is regularly placed in top positions for law and business, both for national and international rankings.

Organization
The University of Cologne is a statutory corporation (Körperschaft des öffentlichen Rechts), operated by the Federal State of North Rhine-Westphalia.

Faculties
The university is divided into six faculties, which together offer 200 fields of study. The faculties are those of Management, Economics and Social Sciences, Law, Medicine (with the affiliated University clinic), Arts, Mathematics and Natural Sciences and Human Sciences.

Rectors
On 24 November 2004, the physicist Axel Freimuth was elected as Rector of the University. His (initially four-year) term began on 1 April 2005. He succeeded Tassilo Küpper and was the 49th Rector since 1919. He was previously Dean of Mathematics and Natural Sciences.

Academic profile
The University of Cologne is member of the association German U15 e.V. which is a coalition of fifteen major research-intensive and leading medical universities in Germany with a full disciplinary spectrum.

Especially the faculties of law and economics are renowned and leading in Germany. Leading researchers are affiliated to Cologne: e.g., Angelika Nußberger, Thomas von Danwitz, Claus Kreß, Martin Henssler, Ulrich Preis, Heinz-Peter Mansel.

Apart from these, affiliated persons with the university have won various awards including Max Planck Research Award, Cologne Innovation Prize (City of Cologne), Postbank Finance Award (Deutsche Postbank), Ernst Jung Prize in Medicine (Jung Foundation), SASTRA Ramanujan Prize, Wilhelm Vaillant Prize (Wilhlem Vaillant Foundation), Heinz Maier Leibnitz Prize (DFG), Alfried Krupp Prize for the Advancement of Young Professors, Innovation Prize of the State of NRW, Karl Arnold Prize (North Rhine-Westphalia Academy of Sciences and Arts).

Rankings
According to the QS World University Rankings, the university held the 268th position globally and the 17th position nationally in 2024. The Times Higher Education World University Rankings for 2023 saw the university at the 160th place globally and 15th place at the national level. In the Academic Ranking of World Universities, more commonly known as the ARWU rankings, for the year 2022, the university was ranked within the 151-200 range globally and between 6th and 9th in the national ranking.

Museums and collections

 * GeoMuseum: The only natural history museum in Cologne
 * Theatre Collection in Schloss Wahn: images and text from European theater from the 16th century
 * Max Bruch Archive of the Institute of Musicology: autographs and writings from and about Max Bruch
 * The Kathy Acker Reading Room, the personal library of author Kathy Acker.
 * Musical Instrument Collection of the Musicology Institute
 * Egyptian collection: Papyri and parchments, ceramics and small sculptures
 * Prehistoric collection artefacts from all periods of prehistoric and early history also from foreign sites, from the Neanderthal fist to the bronze sword and iron weapons of the early Middle Ages
 * Papyrus collection of the Institute of Antiquity
 * Barbarastollen: Under the main building, a mining gallery was built as part of a museum for trade and industry in 1932

Students and faculty
In 2022, the university enrolled 48,214 students. 7,010 Students earned their graduate or undergraduate degrees in 2022.

There were 5,265 students with non-german citizenship in the 2022 Summer Semester. The largest contingents of first year students came from Italy (10.3%), Turkey (8.8%), Poland (9,8%), France (6.6%) and Spain (5,5%).

There are 613 professors at the university, 31% of the professors are female. Including the professors the university employs a total of 4,667 research assistants.

Partner universities
The University of Cologne maintains twenty official partnerships with universities from ten countries. Of these, the partnerships with Clermont-Ferrand I and Pennsylvania State are the oldest partnerships. In addition, Cologne has further cooperations with more than 260 other universities.

 * Federal University of Ceará, Fortaleza, Brazil (since 1990)
 * Sofia University St. Kliment Ohridski, Sofia, Bulgaria (since 1985)
 * Sun Yat-sen University, Guangzhou, Guangdong, China (since 2005)
 * Fudan University, Shanghai, China (since 2010)
 * Université d'Auvergne, Clermont-Ferrand I, France (since 1962)
 * Université Blaise Pascal, Clermont-Ferrand II, France (since 1980)
 * Aristotle University of Thessaloniki, Thessaloniki, Greece (since 1992)
 * National Law School of India University, Bangalore, India
 * Hitotsubashi University, Tokyo, Japan (since 1987)
 * Keio University, Tokyo, Japan (since 1981)
 * University of Wrocław, Wrocław, Poland (since 2003)
 * University of Rajshahi, Rajshahi, Bangladesh
 * Jagiellonian University, Kraków, Poland (since 1990)
 * Maxim Gorky Literature Institute, Moscow, Russia
 * Volgograd State University, Russia (since 1993)
 * University of Seville, Spain
 * Charles University, Prague, Czech Republic (since 1999)
 * Istanbul University, Istanbul, Turkey (since 2003)
 * University of California at Berkeley, School of Law, Berkeley, CA, U.S.
 * Duquesne University, Pittsburgh, PA, U.S. (since 2001)
 * Pennsylvania State University, State College, PA, U.S. (since 1961)

Notable alumni and professors

 * Albertus Magnus
 * Thomas Aquinas
 * Kurt Alder (Nobel Prize in Chemistry 1950)
 * Eberhard Becker (Rector of University of Dortmund from 2002 to 2008)
 * Peter Grünberg (Nobel Prize in Physics 2007)
 * Heinrich Böll (Nobel Prize for Literature)
 * Karl Carstens (president of the Federal Republic of Germany 1979–1984)
 * Gustav Heinemann (president of the Federal Republic of Germany 1969 to 1974)
 * Benjamin List (Nobel Prize in Chemistry 2021)
 * Karolos Papoulias (former president of the Hellenic Republic)
 * Martin Broszat (1926–1989), historian
 * Ute Deichmann, historian
 * Erich Gutenberg (founder of modern German business studies)
 * Amos Grunebaum, obstetrician and gynecologist
 * Dirk M. Guldi, chemist
 * Jenny Gusyk, a Jewish woman of Turkish citizenship, was the first female and foreign student to be enrolled in 1919.
 * Sasa Hanten-Schmidt, lawyer and publicist
 * Leonhard Harding, (born 1936), historian and scholar in African studies
 * Hans Mayer (1907–2001), literary scholar
 * Stephan Noller (born 1970), internet-entrepreneur, founder and former committee chairman
 * Ernst Alfred Philippson (1900–1993), philologist
 * Axel Ockenfels
 * Katja Terlau (born 1970), art historian and provenance researcher
 * Andreas Kaplan, German economist
 * Eberhard Voit
 * Eberhard Wagner, German linguist and author

In popular culture
The University of Cologne was commemorated on the Federal Republic of Germany's postage stamp in 1988, celebrating university's 600 years.

title: University of Cologne