Browse Definitions:
Definition

double-slit experiment

The double-slit experiment is a nineteenth-century investigation into the properties of light that has since been found to demonstrate both the duality of photons and the concepts of superposition and quantum interference.

Debate over whether light is made up of particles or waves dates back over three hundred years. In the seventeenth century, Isaac Newton proclaimed that light consisted of a stream of particles. In the early nineteenth century, Thomas Young devised the double-slit experiment to prove that it consisted of waves. While the implications of Young's experiment are difficult to accept, they are illustrative of quantum theory. The noted physicist Richard Feynman claimed that the essentials of quantum mechanics could be grasped from an exploration of the results of the experiment.

In the double-slit experiment, a beam of light is aimed at a barrier with two vertical slits. After the light passes through the slits, the resulting pattern is recorded on a photographic plate. When one slit is covered, a single line of light is displayed, aligned with whichever slit is open.

Intuitively, one might hypothesize that if both slits were open, the resulting pattern would display as two lines of light, aligned with the slits. What occurs in practice, however, is that light passing through the slits and displayed on the photographic plate is entirely separated into multiple lines of lightness and darkness in varying degrees. The result illustrates that interference is taking place between the waves and particles going through the slits in what a layman might expect to be two non-crossing trajectories.

If the beam of photons is slowed enough to ensure that individual photons are hitting the plate, one might expect there to be no interference and a pattern of light would be two lines of light, aligned with the slits. The results of the experiment, however, indicate the presence of interference. Somehow, the single particles are interfering with themselves. On the face of things, this might seem impossible: we expect that a single photon will go through one slit or the other and will end up in one of two possible light line areas.

That expectation, however, is invalidated by the results of the double-slit experiment. What actually occurs is that each photon not only goes through both slits, but also simultaneously traverses every possible trajectory en route to the target. Research into this phenomenon has demonstrated that other elementary particles, such as electrons, exhibit the same behavior.

This was last updated in March 2011

Continue Reading About double-slit experiment

Join the conversation

2 comments

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

Define young double slit's ?
Cancel
Using relativity to explain the double slit experiment.

Can all the weirdness of double slit experiment be explained by the fact that we are only looking at it from a stationary frame perspective? If you look at the special relativity equation for total energy you see that it has a velocity of the speed of light. For an observer in an orthogonal rest frame to that perspective it looks entirely like a wave of light and would defract and interfere just like light. In our reference frame we observe the momentum energy component and the rest energy component of the total energy separately as the velocity of a particle with rest mass. So it looks like you can have a wave and a particle at the same time. How much wave-like and how much particle-like it looks only depends from what perspective you are looking.

Greg Marlow
marlowg@verizon.net
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

  • audit program (audit plan)

    An audit program, also called an audit plan, is an action plan that documents what procedures an auditor will follow to validate ...

SearchSecurity

  • computer worm

    A computer worm is a type of malicious software program whose primary function is to infect other computers while remaining ...

  • black hat

    Black hat refers to a hacker who breaks into a computer system or network with malicious intent.

  • copyright

    Copyright is a legal term describing ownership of control of the rights to the use and distribution of certain works of creative ...

SearchHealthIT

SearchDisasterRecovery

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

SearchStorage

  • hybrid hard drive (HHD)

    A hybrid hard drive (HHD), sometimes known as a solid-state hybrid drive (SSHD), is a mass storage device that combines a ...

  • USB flash drive

    A USB flash drive -- also known as a stick, thumb or pen drive -- is a plug-and-play portable storage device that uses flash ...

  • open source storage

    Open source storage is data storage software developed in a public, collaborative manner that permits the free use, distribution ...

SearchSolidStateStorage

  • RRAM or ReRAM (resistive RAM)

    RRAM or ReRAM (resistive random access memory) is a form of nonvolatile storage that operates by changing the resistance of a ...

  • JEDEC

    JEDEC is a global industry group that develops open standards for microelectronics.

  • M.2 SSD

    An M.2 SSD is a solid-state drive (SSD) that conforms to a computer industry specification written for internally mounted storage...

SearchCloudStorage

  • Google Cloud Storage

    Google Cloud Storage is an enterprise public cloud storage platform that can house large unstructured data sets.

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

Close