Browse Definitions :

theory of relativity

Contributor(s): Ivy Wigmore

Albert Einstein's theory of relativity is actually two separate theories: his special theory of relativity , postulated in the 1905 paper, The Electrodynamics of Moving Bodies and his theory of general relativity , an expansion of the earlier theory, published as The Foundation of the General Theory of Relativity in 1916. Einstein sought to explain situations in which Newtonian physics might fail to deal successfully with phenomena, and in so doing proposed revolutionary changes in human concepts of time, space and gravity.

The special theory of relativity was based on two main postulates: first, that the speed of light is constant for all observers; and second, that observers moving at constant speeds should be subject to the same physical laws. Following this logic, Einstein theorized that time must change according to the speed of a moving object relative to the frame of reference of an observer. Scientists have tested this theory through experimentation - proving, for example, that an atomic clock ticks more slowly when traveling at a high speed than it does when it is not moving. The essence of Einstein's paper was that both space and time are relative (rather than absolute), which was said to hold true in a special case, the absence of a gravitational field. Relativity was a stunning concept at the time; scientists all over the world debated the veracity of Einstein's famous equation, E=mc2, which implied that matter and energy were equivalent and, more specifically, that a single particle of matter could be converted into a huge quantity of energy. However, since the special theory of relativity only held true in the absence of a gravitational field, Einstein strove for 11 more years to work gravity into his equations and discover how relativity might work generally as well.

According to the theory of general relativity, matter causes space to curve. It is posited that gravitation is not a force, as understood by Newtonian physics, but a curved field (an area of space under the influence of a force) in the space-time continuum that is actually created by the presence of mass. According to Einstein, that theory could be tested by measuring the deflection of starlight traveling near the sun; he correctly asserted that light deflection would be twice that expected by Newton's laws. This theory also explained why the light from stars in a strong gravitational field was closer to the red end of the spectrum than those in a weaker one.

For the final thirty years of his life, Einstein attempted to find a unified field theory, in which the properties of all matter and energy could be expressed in a single equation. His search was confounded by quantum theory's uncertainty principle , which stated that the movement of a single particle could never be accurately measured, because speed and position could not be simultaneously assessed with any degree of assurance. Although he was unable to find the comprehensive theory that he sought, Einstein's pioneering work has allowed countless other scientists to carry on the quest for what some have called "the holy grail of physicists."

See a simple introduction to the theory of relativity:

This was last updated in January 2015

Continue Reading About theory of relativity

Join the conversation


Send me notifications when other members comment.

Please create a username to comment.

Well The Theory Of Relativity Means That Time Travel Is Possible If The Mass Of A Object Is 0 And Speed Is Of Light.I Think That The 0 Mass Is Possible In The Following Way:-
1.The Mass Between The Magnets Attracting Each Other Is Double Between The Magnets Then The Mass Of The Object Repelling Each Other Must Be 0 As 0 Mass Is Possible When Gravity Is In Minus And Minus Gravity Means That The Object Would Repell Not Attract The Object Over Its Gravity And There Would Be The Same Between The Two Objects

Am I Right Please Answer Me And I Would Request You That Can You Reply Me On My Email:-

As I Have A Lot Of Things To Ask
we know that
speed of light=300000 km/h
In light rays small pockets of photon particles are present.

so, we can easily understand that energy produce by light rays is nothing but the kinetic energy of photon particles

If i want to find out how many photon particle are emited if we switch on the circuit contain 1ohm LED , 2 Volt of ideal battery in space (vacume).

we know that
speed of light=300000 km/h
In light rays small pockets of photon particles are present.

so, we can easily understand that energy produce by light rays is nothing but the kinetic energy of photon particles

If i want to find out how many photon particle are emited if we switch on the circuit contain 1ohm LED , 2 Volt of ideal battery in space (vacume).

please answer my question I would request you that can you reply me on my email:-
Personally, I don’t believe we can reverse time, regardless of whether we are travelling at the speed of light or not. Time is constant. If that was the case, then theoretically if we reverse the process, we could go forward in time. The only time ‘perception’ changes from a fixed point is when we are able to observe objects in the distance, using a telescope which has infinite magnification and able to magnify objects faster than the speed of light, so that in theory we are going back in time, relative to where we are in the universe. The only thing that may affect ‘time’ is the potential for alternative or duplicate universes, which may explain why some people have a higher level of psychic ability, particularly those that can predict the future, and others who have the ability to astral travel. There has to be a logical explanation. The problem with science is that it tends to be extremely ‘one dimensional’. If it’s not felt, seen, proved etc, it can’t be factual. We talk about space travel as if we are the only living intelligent species in the universe, totally ignoring what looks to be million year old cave paintings of UFO’s.
If you want to discuss physics, as a 19yo old youth, I used to participate in a practice known as the ‘party trick’, where we would sit a 15 stone guy on a chair & together with a friend firmly press down on the top of his head for 5 to 10 minutes (not a painful press). We would then stand on each side of the chair, place one hand under each of his arms at the armpit & instantly lift him above our heads, with as much physical effort as it takes anyone to raise their arm above their head. The two lifters were both about 10 stone & I generally lifted with one or two fingers, both lifting a combined weight of 200 pounds. Yet, without touching his head before the lift, we couldn’t even as much as move him off the chair. Now someone explain that phenomenon to me…
i believe time zone limited to earth only because time applicability is related to the moving of earth and  outside earth if we go  to universe how do we calculate time?


  • risk assessment

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

  • PCI DSS (Payment Card Industry Data Security Standard)

    The Payment Card Industry Data Security Standard (PCI DSS) is a widely accepted set of policies and procedures intended to ...

  • risk management

    Risk management is the process of identifying, assessing and controlling threats to an organization's capital and earnings.


  • tokenization

    Tokenization is the process of replacing sensitive data with unique identification symbols that retain all the essential ...

  • incident response

    Incident response is an organized approach to addressing and managing the aftermath of a security breach or cyberattack, also ...

  • Federal Information Security Management Act (FISMA)

    The Federal Information Security Management Act (FISMA) is United States legislation that defines a framework of guidelines and ...



  • call tree

    A call tree is a layered hierarchical communication model that is used to notify specific individuals of an event and coordinate ...

  • Disaster Recovery as a Service (DRaaS)

    Disaster recovery as a service (DRaaS) is the replication and hosting of physical or virtual servers by a third party to provide ...

  • cloud disaster recovery (cloud DR)

    Cloud disaster recovery (cloud DR) is a combination of strategies and services intended to back up data, applications and other ...