Are the theories of relativity real?

[Inter.spem.et.metum]

What evidence is there that the theories of relativity are actually laws? Are they applicable? If you must assume certain conditions in the creation of a hypothesis without being able to reproduce the same conditions, then what have you proven? The assumptions that we create make the calculations relational just in principle. What is the purpose of these studies if we are not able to use them?

 

This is not an attack. I would like to understand more about this area.

[freeztar]

What evidence is there that the theories of relativity are actually laws? Are they applicable?

 

Certainly! One very popular example is the GPS system. Newton's laws do not give the accuracy needed, hence the theories of relativity are used and produce great results.

[Jay-qu]

here is a link to some tests that show that relativity must be part of our universe. It includes such experiments as the Michelson-Morely experiment and observations of binary stars.

 

There have been many tests and so far they have shown that time dilation from relative velocities or gravitational fields are very much real.

[kmarinas86]

here is a link to some tests that show that relativity must be part of our universe. It includes such experiments as the Michelson-Morely experiment and observations of binary stars.

 

There have been many tests and so far they have shown that time dilation from relative velocities or gravitational fields are very much real.

 

Given a constant relative velocity, obviously the image of something will be time dilated, but does that mean that the object itself must be time dilated as well?

 

I know acceleration causes an absolute dilation of time, which can be measured as clocks have been sent into space and then returned to earth. I do not yet believe that the same would be true for objects moving a constant relative velocity. I think that in SR (special relativity), it's just the image that's being time dilated.

[Buffy]

Given a constant relative velocity, obviously the image of something will be time dilated, but does that mean that the object itself must be time dilated as well?

You might want to try to define what you mean a little bit more clearly. No, the object itself "was" not "time dilated," it and the observer *experienced* time dilation by respectively moving and observing. If they get together at the end, their clocks will differ, and that difference in the clocks is how they "experience" it. To each of them in their own reference frame, they will not "experience" anything being different at all.

So when you say:

I know acceleration causes an absolute dilation of time, which can be measured as clocks have been sent into space and then returned to earth.

There is nothing "absolute" about it: the difference is purely an effect of the *relative* motion between the two observers.

 

And as a result:

I do not yet believe that the same would be true for objects moving a constant relative velocity. I think that in SR (special relativity), it's just the image that's being time dilated.

...is sort of true, since both "observers" don't "feel" anything wrong.

 

This is similar to one observer seeing the "traveling" party appear to be forshortened (a related effect of SR): the traveler does not "feel" squished" and in fact is *not* physically squished: its the *appearance* to the observer that's squished. So in that sense its not "real" in the sense that it is not "physical."

 

But that doesn't mean that SR isn't "real," just that you need to be careful in interpreting the words used to describe it.

 

Blue-shifted,

Buffy

[Little Bang]

Michelson-Morley only showed that the material of space had no effect on the speed of light.

[Jay-qu]

Michelson-Morley only showed that the material of space had no effect on the speed of light.

Or more specifically that the speed of light is independent of the relative motion of the observer.

[Qfwfq]

If you must assume certain conditions in the creation of a hypothesis without being able to reproduce the same conditions, then what have you proven?

Exactly which conditions that can't be reproduced?

[Inter.spem.et.metum]

Why is it still called a theory?

[Jay-qu]

from thefreedictionary.com -

Theory: A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.

 

No matter how good a theory describes the world we live in, all it does is describe what we can see and test. We have been shown many times in the past that when we think we know something, bam physics throws a curve ball. In 100 years these theories may not be the best description of the world, but they still remain a description of the world and may work fine for most purposes.

[snoopy]

What evidence is there that the theories of relativity are actually laws? Are they applicable? If you must assume certain conditions in the creation of a hypothesis without being able to reproduce the same conditions, then what have you proven? The assumptions that we create make the calculations relational just in principle. What is the purpose of these studies if we are not able to use them?

 

This is not an attack. I would like to understand more about this area.

 

 

Yes I think that everyone has pretty much covered your question, to which the answer is yes we do seem to live in a relative universe.

 

But I understand your concerns as it is counter intuitive but many things in physics are.

 

I understand its not an attack but a enquiry but what difficulties do you have with Relativity ?

 

I would be genuinely interested to know ?

 

Cheers :)

[Inter.spem.et.metum]

GPS is one example of how to applies these theories. What are some others? What is the long term goal of this area of study?

[Jay-qu]

GPS is one example of how to applies these theories. What are some others? What is the long term goal of this area of study?

I would say to describe the world to as much accuracy as possible.

[Erasmus00]

Why is it still called a theory?

 

This assumes there are hard rules for deciding between theory and law. This is not true, things are called laws for largely historical reasons. There is effectively no difference between the terms.

 

GPS is one example of how to applies these theories. What are some others? What is the long term goal of this area of study?

 

There are a few key things to understand about relativity. First, special relativity is more than a theory, its a framework for building theories. Special relativity allowed for the development and formulation of quantum field theories (of which QED is the most accurate theory we have ever tested).

 

Second, no one really studies relativity any more, its pretty much a complete theory. People who use general relativity in their work use general relativity to study simulations of things like star formation, or colliding stars. The long term goal here is to better understand star formation, gravity waves, etc.

-Will

[jedaisoul]

I assume that you are referring to Einsteinian relativity (there is also Newtonian relativity). On that basis I would suggest that there are two aspects to this question:

 

a) Does Einsteinian relativity give us more accurate results than Newtonian relativity? I think that most scientists working in the field would say "yes", and they are the best judges on that issue. Does that make them laws? I'm not sure.

 

:eek_big: Does Einsteinian relativity describe the real universe? I think the answer on that is no. The reason is that Minkowski space-time is an abstract idea that exists only in our imaginations. Why am I sure this is so? Because it treats time as a dimension, in the same sense as the spatial ones are. What is wrong with that? Well, quite a lot. The most obvious flaw is that the molecules and atoms that exist at different places in space are different entities. But the molecules and atoms that exist at different times are (mostly) the same entities. That is a huge difference. Equating time as a dimension in the same sense as the spatial ones are is mathematically valid, but, in my opinion, conceptually flawed.

[Qfwfq]

Does Einsteinian relativity describe the real universe? I think the answer on that is no. The reason is that Minkowski space-time is an abstract idea that exists only in our imaginations. Why am I sure this is so? Because it treats time as a dimension, in the same sense as the spatial ones are. What is wrong with that? Well, quite a lot.

A modern (since Minkowski) treatment of SR posits space as being isotropic and homogeneous and space-time as being homogeneous but not isotropic. What's wrong with that?

 

The most obvious flaw is that the molecules and atoms that exist at different places in space are different entities. But the molecules and atoms that exist at different times are (mostly) the same entities. That is a huge difference.

Instead of inventing the wheel, look up the definition of world line. Of course you are arguing in terms of classical particles, in terms of optics the matter is totally different.

 

Equating time as a dimension in the same sense as the spatial ones are is mathematically valid, but, in my opinion, conceptually flawed.

This depends on what you mean by "equating ... in the same sense". SR itself distinguishes spacelike, timelike and null directions.

[jedaisoul]

A modern (since Minkowski) treatment of SR posits space as being isotropic and homogeneous and space-time as being homogeneous but not isotropic. What's wrong with that?

I'm not sure of the relevance of homogeneity and/or isotropism. I'm talking about whether space-time exists physically or not. Whether mathematically space-time is homogemeous but anisotropic has no bearing on whether it exists or is just a matematical construct. At least, that is my understanding. You seem to be starting from the assumption that space-time exists, or that its existence is not important to you? My apologies if I've misrepresented your meaning.

 

Instead of inventing the wheel, look up the definition of world line. Of course you are arguing in terms of classical particles, in terms of optics the matter is totally different.

The concept of time travel inherently involves atoms and molecules being in two places at the same time and/or not being in any place at another time. Example: Lets assume that I have a bowl, an apple and and a time machine...

 

a) At time 1, I place the apple in the bowl. The "second" me places the "second" apple in the bowl. So there are two apples in the bowl.

 

:winter_brr: At time 2, I pick up the first apple from the bowl and walk away from the table. The "second" me travels to time 5. The "second" apple remains in the bowl.

 

c) At time 3, I travel back in time to time 1 with the apple in my hand, becoming the "second" me at time 1.

 

d) At time 4, Neither I nor the "original" apple are there. Only the "second" apple remains in the bowl.

 

e) At time 5, The "second" me returns. So there's only one apple and only one me again.

 

You can describe my, the apple's, and the bowl's behaviour in three different world lines, but does that make it credible?

 

So I repeat: The molecules and atoms that exist at different places in space are different entities. But the molecules and atoms that exist at different times are (mostly) the same entities. That is a huge difference.

 

This depends on what you mean by "equating ... in the same sense". SR itself distinguishes spacelike, timelike and null directions.

But what does this mean? Are you saying that time travel is possible or not? If it is, how do you explain the example above? If not, what is the point of having a four dimensional model?

 

Anyway, I'd be interested to hear your comments. Please accept my apologies for the delay in replying. Regards, Terry.