The same is true in GR — Agustino

If you look at the link, you will observe that GR is used in the explanation for galaxies accelerating faster than light, even though SR denies the possibility.

I really try to refrain from arguing Relativity because unlike QM which is simply the Schrodinger equation, Relativity it's a mass of conflicting ideas which truly no one agrees on. Every single answer is different.

If you look at the link, you will observe that GR is used in the explanation for galaxies accelerating faster than light, even though SR denies the possibility. — Rich

No it doesn't. Spacetime itself expands faster than light, but spacetime isn't actually an object the way galaxies, planets, etc. are. Galaxies, etc. travel in spacetime, but spacetime doesn't travel in anything.

No it doesn't. Spacetime itself expands faster than light, but spacetime isn't actually an object the way galaxies, planets, etc. are. Galaxies, etc. travel in spacetime, but spacetime doesn't travel in anything. — Agustino

Space-time are defined differently in SR and GR.

Really, it is off no use. I provided the link which clearly states the contradiction. That you disagree with the link's description underscores my point. Are we to begin yet another neverending discussion on the meanings of SR and GR. They already exist by the thousands on the Internet. Another one would be superfluous.

To sum up the whole discussion. We have no idea whether the universe is expanding or not. Some say it does, some say it does not.

Space-time are defined differently in SR and GR. — Rich

Yes of course they are! What did you expect? It's like telling me that space is defined differently in Euclidean and Non-Euclidean geometry. This of course doesn't change the fact that Euclidean geometry is nothing but a subset of Non-Euclidean geometry, just like SR is a subset of GR which applies only in a LIMITED set of circumstances/conditions.

I provided the link which clearly states the contradiction. — Rich

This one?

"The upshot of this is that free fall is inertial motion: an object in free fall is falling because that is how objects move when there is no force being exerted on them, instead of this being due to the force of gravity as is the case in classical mechanics.This is incompatible with classical mechanics and special relativity because in those theories inertially moving objects cannot accelerate with respect to each other, but objects in free fall do so. To resolve this difficulty Einstein first proposed that spacetime is curved. In 1915, he devised the Einstein field equations which relate the curvature of spacetime with the mass, energy, and any momentum within it." — Rich

That 'contradiction' was resolved by GR. That's why GR was invented.

I can confirm this attitude in Physics forums. They are very good at regurgitating textbook knowledge and abhor critical questions. I have even been banned just for daring claim that Optics is not necessarily correct. My confidence in critical thinking among scientists, whether forum users or academics, is very low. — Hachem

At some point in ones life one must decide to say the "heck with it". It is a confused morass of ideas and opinions and it is better just to ignore and move on. Anyone interested in the subject is invited to investigate on their own. Who better to demonstrate nasal if the contradictions than the physicists themselves.

— Rich
That 'contradiction' was resolved by GR. That's why GR was invented. — Agustino

I suggest then that SR be completely dropped and all that it implies. That will really eliminate the contradictions!

I suggest then that SR be dropped and all that it implies. That will really eliminate the contradictions! — Rich

SR has been dropped when GR has been adopted. Really... you seem behind on science.

The only reason SR is taught is the same reason Euclidean geometry is taught. They are applicable in specific circumstances, but not in all. If you want something applicable in all circumstances, you go to GR and non-Euclidean geometry respectively.


See this? GR is in Space Curvature.

It's as silly as asking why we still calculate using Newton... well, because it works if space is locally flat, which happens to be the case around here on Earth. So why do we calculate using SR? Because it works around here on Earth where spacetime is relatively flat, and for non-accelerating reference frames. Whenever there is an acceleration - such as your almost speed of light train stopping in the middle of the tunnel - you can no longer apply SR.

SR has been dropped when GR has been adopted. — Agustino

Whoops! All those books on SR need to be pulled from the library shelves immediately. This can be a PR nightmare. What should we do about the millions of references on the Internet?

Whoops! All those books on SR need to be pulled from the library immediately. This can be a PR nightmare. What should we do about the information on the Internet? — Rich

Are you doing this on purpose?! Do all books on Newton's theories have to be dropped out of the library because his theory has been replaced by GR?! Do we need to get rid of Euclid's Elements because Euclidean geometry has been replaced by Non-Euclidean geometry (which by the way, also includes Euclidean geometry itself?)?

non-accelerating reference frames. — Agustino

Exactly how many areas of the universe are without gravitational space-time?

Really, must we go through this?

Exactly how many areas of the universe are without gravitational space-time?

Really, must we go through this? — Rich

None, that's why SR, much like Newton's theory and Euclidean geometry provide USEFUL approximations. They're easier to work with and calculate than their more complex parents.

I say drop SR and all of its implications including no preferred frame of reference.

Are you doing this on purpose?! Do all books on Newton's theories have to be dropped out of the library because his theory has been replaced by GR?! — Agustino

All of the implications of Newton's theories contradict SR. You can't say there is a preferred frame a reference (Newton), then say there isn't (SR), and then say there is (GR). You can't say nothing can move faster than light and then say whole galaxies can. Actually, you can, because that is exactly what Relativists are doing.

It is a mess.

I say drop SR and all of its implications including no preferred frame of reference. — Rich

It seems you are confused. When I assume that the internal angles of a triangle are 180 degrees and proceed to calculate using that assumption, I don't actually think it's true. Absolutely not. I think it's an approximation of the truth, which is good enough to give me an estimate for the answer that I'm looking for with sufficient precision for my needs.

All of the implications of Newton's theories contradict SR. You can say there is a preferred frame a reference, then say there isn't, and then say they is. Actually, you can, because that is exactly what Relativists are doing. — Rich

Sure. So what? Newton isn't applicable where SR is applicable, BUT SR is applicable where Newton is applicable. Likewise, SR isn't applicable where GR is applicable, but GR is applicable where SR is applicable.

There it goes. I'm confused. OK. I'm OK with that. As I said, I invite others to investigate and come to their own conclusions.

Beware, as Bergson warned, do not give Relativity and any of its implications, ontological status.

I say drop SR and all of its implications including no preferred frame of reference. — Rich

When you say this, it's just as silly as telling me to drop Euclid's 5th Postulate when doing Euclidean geometry because it's not true. Absurd.

Yes, it's not true. But that assumption approximates local conditions sufficiently such that it is useful.

There it goes. I'm confused. OK. I'm OK with that. As I said, I invite others to investigate and come to their own conclusions. — Rich

Yes, but this belies a complete misunderstanding of how science works. Science doesn't work by finding out what is "true". It works by approximating what is true. It says for this group of situations, things behave as if the internal angles of a triangle add up to 180 degrees because the curvature of spacetime is almost 0.

The assumptions you are worrying about are neither true nor false, but useful. That's why they are assumptions and postulates, and not truths.

The assumptions you are worrying about are neither true nor false, but useful. That's why they are assumptions and postulates, and not truths. — Agustino

I wouldn't have any problems with that. Only, as Rich indicated, RT and QM come with ontological claims and so does contemporary science. This thread is a clear example of these ontological claims. Is the universe expanding? That is neither merely an assumption, nor an approximation but a hard claim that the universe as we know it is expanding.

That is what I meant with cosmology is metaphysics with mathematical formulas, and that is what I think Rich means when he says we should beware giving ontological value to RT and QM

That is what I meant that cosmology is metaphysics with mathematical formulas, and that is what I think Rich means when we say we should beware to give ontological values to RT and QM — Hachem

This was the essential object that Bergson had to Relativity. Robbins raises the same objection.

It is one thing to say that the equations are useful. It is quite another to elevate the equations to an ontology.

This was the essential object that Bergson had to Relativity. Robbins raises the same objection.

It is one thing to say that the equations are useful. It is quite another to elevate the equations to an ontology. — Rich

It depends which equations you elevate to ontology. You should elevate the most general framework. In the case of gravity, this would be general relativity, and NOT special relativity or Newton's laws.

It depends which equations you elevate to ontology. — Agustino

How about space-time? Should it be elevated to an ontology?

How about space-time? Should it be elevated to an ontology? — Hachem

Spacetime effectively is GR.

is that a yes?

is that a yes? — Hachem

Yes.

Then you are expressing one of the contradictions Rich was warning about.

Then you are expressing one of the contradictions Rich was warning about. — Hachem

Nope, Rich has a problem with SR, not with GR.

I won't speak for Rich, but I find the concept of space-time a metaphysical monstrosity.