Einstein equations don't work at large scale?

[Dale]

How universe works that way if we find that relativity don't works at large scale and quantum world?

Because we have found experimentally that it does work at scales like 4 m and 50 km/h to 200 km/h. If we eventually find that it doesn’t work at cosmological scales that will not change the experimental fact that it does work at the everyday scales you mentioned.

 

[sbrothy]

Maybe better word is logic , instead intuition.


Will Newton laws still be just approximation if one day we find that time is absolute?

If gravity is correct we will not have these problems today.

Maybe one day we will find theory that is correct from 10^-35m to 10^27m

I guess that's the dream!

 

[Ibix]

Will Newton laws still be just approximation if one day we find that time is absolute?

Of course. We have observational and experimental evidence (a lot of it!) of Newton's laws being violated, some of it pre-dating the discovery of relativity. You can't wish that away.

 

[gen x]

Of course. We have observational and experimental evidence (a lot of it!) of Newton's laws being violated, some of it pre-dating the discovery of relativity. You can't wish that away.

What are all reasons why newton laws fail? exclude quantum physics

 

[Sagittarius A-Star]

What are all reasons why newton laws fail? exclude quantum physics

Newton's law of gravitation predicts a too slow precession of planet Mercury’s orbit, mainly because it did not include spacetime curvature.

Walter Ritz wrote in 1909:

Astronomical observations carried out over many centuries have revealed some deviations between observation and calculation, which cannot be explained by Newton’s law up to now, and which a new theory will have to explain. Of these anomalies by far the largest is of the planet Mercury, whose ellipse precesses slowly, under the effect of the remaining planets; but the observed precession is larger by approximately 42 arc-seconds per century than the computed. The difference is small, but nevertheless unquestionable and unexplained.

Source:
https://www.mathpages.com/rr/s8-10/8-10.htm

 

[Ibix]

What are all reasons why newton laws fail? exclude quantum physics

All of them? Seriously?

For starters there's the anomalous precession of Mercury (and the other planets). There's GPS time dilation. Accelerator experiments such as Bertozzi's (on YouTube). Gravitational lensing of light. Fizeau's experiments with light in water. Anything that shows the invariance and source independence of light speed. The existence of magnetic fields around current carrying wires.

The fundamental reason for all of this is that the fundamental forces appear to be Lorentz covariant, not Galileo covariant. Thus literally every physical interaction (except gravity) obeys SR, not Newton, and gravity obeys GR. Exactly how GR and quantum theory fit together is the big question - everything else fits in.

 

[gen x]

All of them? Seriously?

I didnt mean all examples of where Newton physics cant be used, I mean reasons why theory is wrong..
So he use absolute space and time, dont have finite speed etc...

 

[Ibix]

So he use absolute space and time, dont have finite speed etc...

He (implicitly) assumed the invariant speed was infinite. Einstein realised it must be finite and equal to light speed. All the other differences stem from that.

 

[gen x]

He (implicitly) assumed the invariant speed was infinite. Einstein realised it must be finite and equal to light speed. All the other differences stem from that.

Einstein already knew that speed of light is constant from past experiments.

<edited by mentor>

 

[Ibix]

He (implicitly) assumed the invariant speed was infinite. Einstein realised it must be finite and equal to light speed. All the other differences stem from that.

Note that this is very much a modern retrospective view of it. The actual history is somewhat more tangled, and I very much doubt Newton thought in such terms. Interestingly, had he done so, the mathematical tools to discover relativity were available to him (although due to experimental limitations he would only have been able to say that if the invariant speed is finite it is much larger than anything he could measure).

 

[Ibix]

Einstein already knew that speed of light is constant from past experiments.

Sort of. There were a lot of patches to electromagnetic theory that amounted to SR, but they had not been recognised as such. Poincaré famously published the complete maths for relativity in 1904, but still clearly saw it as a bunch of weird fixes to Maxwell's equations. Einstein's insight was to realise that they weren't fixes to Maxwell, they were a replacement for Newton, and to rederive them from what we would now call symmetry considerations rather than (highly precise!) empirical bodging.

Do you think Newton work is greater then Einstein?

I don't know of a meaningful way to compare them.

 

[PeterDonis]

Einstein already knew that speed of light is constant from past experiments.

Newton didn't when he developed his mechanics, which he did in the mid-1660s, but didn't publish until his friend Edmund Halley badgered him into it in the 1680s. The Michelson Morley experiment, which was the first indication that the prevailing theory of light, which predicted that its speed should vary depending on your motion relative to "absolute space", might be wrong, did not happen until the 1880s.

 

[Dale]

Of course. We have observational and experimental evidence (a lot of it!) of Newton's laws being violated, some of it pre-dating the discovery of relativity. You can't wish that away.

Yes, and we also have lots of evidence validating Newton’s laws. We can’t wish that away either. The existence of that evidence is why Newton’s laws are still valid in the classical domain.

A lot of people in the OP’s position struggle because of an overly simplistic black and white view of scientific theories. The fact is that subsequent data does not undo previous data. Relativity will always be valid where experiments have already confirmed it, just as Newton’s laws will always remain valid where experiments have already confirmed it.

 

[Dale]

I mean reasons why theory is wrong.

The only way to know that a theory is wrong is to obtain measurements that contradict it.

So he use absolute space and time, dont have finite speed etc.

Those are reasons why Newtonian physics differs from relativity. But the reason why it is wrong is not because it differs from relativity. It is wrong only insofar as it differs from experimental observations.

What we can say is that where Newtonian physics differs from relativity, it also differs from the evidence. And where it matches the evidence it also matches relativity. So where Newtonian physics is right, relativity is also right. But the reverse is not always true.

 

[gen x]

Yes, and we also have lots of evidence validating Newton’s laws. We can’t wish that away either. The existence of that evidence is why Newton’s laws are still valid in the classical domain.

A lot of people in the OP’s position struggle because of an overly simplistic black and white view of scientific theories. The fact is that subsequent data does not undo previous data. Relativity will always be valid where experiments have already confirmed it, just as Newton’s laws will always remain valid where experiments have already confirmed it.

When you said valid, you mean accurate enough? So F= 40 N instead F=40.000000001 N

 

[Dale]

When you said valid, you mean accurate enough? So F= 40 N instead F=40.000000001 N

I mean accurate to within the experimental precision.

 

[gen x]

I mean accurate to within the experimental precision.

Experimental devices for engineering & technology in low every day speeds, can't even show relativistics results, because they are so small?

 

[PeterDonis]

Experimental devices for engineering & technology in low every day speeds, can't even show relativistics results, because they are so small?

We have plenty of experimental devices that can show relativistic effects. Indeed, we have "everyday" engineering and technology that would not work if we did not correctly take such effects into account, such as GPS.