Einstein's theory of relativitiy?

Question

This theory is based on the premise that the speed of light never changes, even if the source is moving. How could he be so sure that this is true?

Answer 1

His theory stemmed from experimental results of others, not the other way around.

The original experiments were done by Michelson and repeated by Moreley at the end of the 19th century. They measured the difference in the speed of light going down two paths at right angles to each other as they rotated their apparatus. Because the Earth is moving round the Sun quite fast, this means that sometimes one arm was pointing in the direction of movement while the the other was perpendicular to it. This would lead to a measurable speed difference if the speed was additive, but none was found.

It was hence concluded that the speed of light was constant for all frames (they had effectively tested an aweful lot).

Answer 2

First of all, what we commonly refer to as a "theory" and what is a scientific theory are two completely different things. For something to become a scientific theory is has to start out as a hypothesis and be tested by thousands of experiments. If none of those experiments prove the hypothesis wrong, it can become a scientific theory (in science, there is no such thing as proving something "right" - it is merely not proven wrong). So something that is considered a scientific theory, such as Einstein's Theory of Relativity, is widely considered as being true. It has never been proven false under any circumstances. So don't question Einstein when almost all of the scientific world agrees with him (at least on this matter).

Einstein was a brilliant man. He understood that physics is the most basic of sciences and that understanding physics before any other scence will give you a grander understanding of science in general. He took scientific facts and used logical reasoning and extended experimentation to support his hypothesis, which eventually became a scientific theory.

Now there are actually two theories of relativity: Einstein's theory of special relativity and general relativity. The theory of special relativity describes the relationship between matter, space, and time. It shows that e=mc^2 and that measurements of mass, distance, and time change or dilate as velocity approaches the speed of light. You are referring to the theory of special relativity. The theory of general relativity encompasses more forces of the universe and is, well, more general - it even concerns gravity and acceleration.

Well, anyway, after giving you and others a background, I guess you deserve a concrete final answer. Einstein is sure that the speed of light never changes (in a vacuum) because many scientists performed the following experiment.

Have a spaceship move away from a space station at high speeds and send back a signal (all electromagnetic signals travel at the speed of light in a vacuum and only have a different frequency than visible light). Measure the distance the two bodies are away from each other and measure the time it takes for the signal to reach the space station (then compute the speed). Then perform the experiment with the space shuttle moving toward the space station. Are the two speeds of light equal? Yes - they are!

You would think that they wouldn't be. If you are on a moving platform and throw a ball forward, it will have a greater speed relative to the ground than it would if you threw the ball at rest and would have a lesser speed relative to the ground if you threw it in the opposite direction of the moving platform (this is because the speed of the platform is added or subtracted to the speed that you can throw the ball). Wouldn't the same be true for light being "thrown" off of a moving "platform". No! It wouldn't. Light behaves differently. Light travels at the maximum speed that anything can travel - the speed limit of the universe (at least, matter cannot travel faster than light - some experiments are leading scientists to believe that some particles can - some have imagined superfast particles called tachyons).

Amazing! The speed of light does not change "even if the source is moving".


(OK - this is just a side note - to some of the other people who answered this question and do not know what they are talking about. 1) Einstein is right - he is awesome - he is brilliant - do not question him. 2) Many scientists of this day and age understand everything that Einstein said and have even surpassed his ideas - just because they are modern scientists building off of his great pioneering work - not because they are better. 3) Just because scientists have discovered that some particles can travel faster than the speed of light or that events can occur faster than the speed of light does not mean that Einstein's theory of relativity is false - nobody has ever shown that matter can even reach the speed of light. I could explain this but that would take a reaaally long time.)

Answer 3

eienstein's theory of relativity states that speed of light is constant and there is relation between energy and mass. E=mc2
m=m.(1-(v/c)2)1/2
where m.=rest mass and c is speed of light.
m is mass at speed v

This theory is based on the premise that the speed of light never changes.
Yes, this theory is right.But, Last year i read a news that scientist made conclusion on their observation that light coming from far galaxy having a variable speed. and also i read another news which was observed in the laboratory that scientist made strikes two particles and they came on conclusion that a particle formed which has a speed larger than the speed of light. This two experiments contradict the eienstein's theory of relativity.
But, I am supposed eienstein's theory of relativity is universal law.

Answer 4

actually its very simple einstein had 2 theories relatin relativity i.e. he stated that the speed of light is constant but ven u r movin vith the speed seems 2 change but it actually remains constant but iff that doesnt change should'nt sumthin change that sum thin is light and led 2 the idea of a 4d universe and so on into time travel but the point 2 be remembered is that there is relative motion between light time and the movin body and then came the special theory of relativity and says if great force acted on light light vould bend such a force vich can do dis is gravity and so gravity vas given its intro for eg u place a metal ball on a very soft bed now if the path of light is that curve than light vould bend so light vould bend thus notobeyin the law of rectilinear probigation but it only seems 2 bend such is vat vas seen near the sun as light bent as it vent 2vards the sun this vas cause light 2ook the path of the suns gravity

Answer 5

The theory is base on the premise that people are burning and I have no way of getting rid of this factor. Light is evil and it will never do anything for me, I'm scared, light is evil and it will never do anything for me, I think I'll make that known

Answer 6

In this day and age, we've already slowed the speed of light in labs. Therefore, if the premise you've stated is his actual premise...? He was wrong. Congratulations! You're smarter than he was - in a way...

Answer 7

when he first published this theory,only a dozen scientists were able to understand what he actually wanted to say!even now this theory is not approved by all mankind.but all think that einstien must have proved it otherwise he won't publish it in public,all believe that we should just accept this theory,because till now,nobody(exept einstien ofcourse!) is able to prove this theory praticaty or mentally..so just accept it (if a new einstien borns again,he must be able to prove it again!!!)

Answer 8

He probably found ways to test it as much as he could, but there's a reason it's a THEORY.

Answer 9

HE can't, that's why it's called a THEORY.

Answer 10

dude its a THEORY!!!!! i dont think he was sure because if he was it would be called a LAW