Are laws of nature really the same in all reference frames?

Bjarne

You misunderstood what I wrote above.
I am not saying that relativity is wrong, but only that the proportionately between ADG and Square increase 1:1 , as a result of the equation itself, - is true ( in a classic sense).
That things are different in relativity is a different history.

I agree that the equation gives contradictory result when compared to relativity; at least we must expect the result of it to be limit to local space-time.

The point is only that I wonder whether the equation when put right together with other facts, for example Schwarzschild , and relativity , - could it maybe be so that the proportionality 1:1 reveals a aspect of a law of nature that we have overlooked, and that maybe not is in conflict with relativity, but instead forms a synthesis?

I don’t know, I am not an expert in this field, but I think the proportionality is remarkable, and maybe could be a clue to discover something that maybe could have been overlooked .

One thing is that time ticks different, and that space is really strange, but another question is; - are there more to discover in this field? Or have we fully understood the nature of space?
I mean we know matter is deforming space.
From a classical perspective we see that ADG and square increase is connected proportionally 1:1 , - this could at least be a clue to better understanding. So long we don’t know what this really reflect, if anything, it could be stupid to ignore it.
Which experiment do you have in mind ?

“The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth.” Niels Bohr

DaleSpam

The equation a=GM/r² is the fundamental equation of Newtonian gravity, so any observation which falsifies Newtonian gravity falsifies that equation. Those observations include:

The anomolous precession of Mercury
The orbital decay of PSR1913+16
Geodetic precession (Gravity Probe B)
Gravitational lensing/deflection
Shapiro delay experiments

All of these experiments falsify Newtonian gravity. It is no use repeating the claim that a=GM/r² is a law of nature when nature disagrees.

Bjarne

I agree that the "problem" to the Newtonian equation is that because of space-time disturbing "r" in the equation is twisted by space-time, whereby the classic understanding not can be completely correct.
But after modifying from that influence I am not sure the equation is so bad (?).

Before digging deeper into this let us first finish what the Shapiro delay really must mean.

1 second at the ISS is still 1 second, but comparable to 1 second at the Earth it is "stretching" at the ISS.
Hence 1 second at the ISS is comparable longer.

Speed on board the ISS (e.g. the speed of light) is comparable slower as speed on the earth

I am often walking round a lake near my hometown.
If we would copy that lake and paste it into a low gravity planet, - it will still (locally) take me the 'same' amount of local time, - to walk around it.
My speed would also locally be the same, - but time (1 second and speed) would comparable to the same tour on Earth both be ‘stretching’ factors (comparable slower).

Anyway I assume I would not have any feeling of moving in slow motion, everything would be the 'same' both places.
So is it not true to say that also distances (the ruler) at the ISS, - is a relative proportional comparable stretching factor too, - so like both time and speed also are ?

Let say the size of the kitchen on board the ISS is identical to one in my house, but on board the ISS it is stretching proportional with time and speed.
But locally everything seems exactly the same as on Earth.

(Sizes is off course exaggerated)
It would still take the ‘same’ time to walk (with the ‘same’ speed) from A to B, - doesn’t matter in which space-time that kitchen would be.

Do we know whether distance is a streching factor too?

Or its it only possible that also distances are comparable different in different space-time, - (without violating any laws of nature)?

I mean why is time really ticking comparable different?

Is it “because” also distances are comparable different?

If not also distances are affected it is hard even to imagine how my tour round the lake on a low gravity planet would be?

At least I would discover something is wrong, - due to 'slow motion'.
If distance also is stretching proportional factor together with time and speed, - everything would be “normal”.

Many experiments have been done when it comes to speed and time, - but what about local distances, why should they be comparable the same everywhere, (if that really should be so) ?

So what can we say for sure here ?

DaleSpam

I never said it was bad. In fact, I have repeatedly said that it is a close approximation in many circumstances.

Nevertheless, it is not a law of nature.

How exactly do you plan on making the comparison?

zonde

When it is clear that there is significant domain where assumptions of the theory hold good you do not say that theory is falsified but instead you say that experiments have established it's domain of applicability.

So no, these experiments do not falsify Newtonian gravity. And because Newtonian gravity talk only about massive objects optical observations (Gravitational lensing, Shapiro delay) have nothing to do with it's predictions.

Bjarne

Maybe, maybe not, - I am not convinced, but I have also not taken any decision.
Have we understood the full range of relativity?
Never say never.

Sorry, - I mean the opposite
1 second at the ISS is still 1 second, (the definition is correct) but comparable to 1 second at the Earth, time (1 second) is "stretching" at the Earth.

Hence 1 second at the ISS is comparable shorter at the ISS.
When time (1 second) compared to time at a different space-time is "stretching" and speed can be said to doi the same (since speed of light always is the "same") - what prevent us from assuming that also distances are doing exactly and proportional the same,- so that also the 1 meter ruler still is one meter, but comparable stretching, exactly the same rate as speed and time. ?

So the question is, - is the "big kitchen" and "big lake" etc... (together and proportional with strech of time and speed) also "stretching" on the Earth, and comparable "shrinking" in lower gravity space time, as for example on board the ISS or on a low gravity planet etc…?

At least this would make sense, when I would imagine how it would be to jump to an (extreme) different time space reality and walk around. I would expect everything to be the same, - but not comparable the same. (except the magnitude of gravity).

DaleSpam

I am fine with this phrasing. Nevertheless, Bjarne's scenario dealing with gravitational time dilation is outside the domain of applicability of Newtonian gravity.

I disagree here. While the gravitational force between a massive object and a massless object is 0 according to Newton's laws it doesn't take force to accelerate a massless object. So the acceleration of massless objects in Newtonian gravity is still given by a=GM/r².

DaleSpam

That is not an indication of a failure in physics or relativity.

Again, how exactly do you plan on making the comparison?

Bjarne

I don't understand the question..
Time, and hence 1 second is not comparable the same in different space time, - do you not agree to that?

DaleSpam

I am asking for a detailed description of what experiment you are planning on doing in order to compare a 1 s on the ISS to 1 s on the earth, and how are you going to interpret different possible results of that experiment in terms of comparing the seconds?

Bjarne

I cannot see the problem.
Clocks ticks different in different space time.
Let us say you were living in a relative very strong gravitionel field, compared to me.
Let’s say it will take 2 second on my atomic clock, - to observer one second ticking on yours atomic clock.

Opposite it will take you ½ second to observe 1 second ticking on my atomic clock.

The definition of 1 second is for both of us 9,192,631,770 cesium frequency cycles per second.

But it will take a comparable long second (relative double period “of time”) for your clock to reach this number, and only a relative comparable short (½) period, and hence a short second for me to count the same numbers of frequencies.

So the comparable second is not the same. I cannot understand how you seem not to agree to that.

DaleSpam

You are going in circles. I ask you how you are making the comparison and you simply assert that they are "different". Since "different" is a comparison where you find that they are not equal that still leaves the question of exactly how you are making the comparison.

Please answer the question. How are you comparing clock rates at different points in spacetime?

What is the experiment you are proposing here? How do you "observer" the time ticking on your clock and mine?

Bjarne

Satellites proves this every day

The same answer as above.
I cannot see any other option, - can you ?

Mentz114

Bjarne, your answers are getting more and more feeble. I think you misunderstand what is meant by "the laws of physics are the same in all inertial frames" so I'll spell it out.

If an experiment is done in lab A to test the law f=ma using billiard ball type experiments and of course measuring with local clocks and rulers, then the result will be the same as in any other lab frame, where of course, they use their local clocks and rulers.

It matters not a jot if the local clocks and rulers are 'different', both frames will verify that f=ma is true, up to a small experimental error.

Going on about seconds or centimeters being different in different frames is irrelevant.

DaleSpam

Sure, I can see at least 4 ways to compare two distant clocks:

A) Broadcast a reference signal, measure the frequency of the signal locally at each clock
B) Take a reference clock, physically transport it from one clock to the other and measure the rate of the reference locally at each clock
C) Agree on a standard physics experiment as a reference, perform it locally at each clock and measure the time for the experiment
D) Agree on an astronomical reference, and measure the time for the astronomical reference locally

Your suggested measurement of one year with two clocks is an example of D. Your mention of satellites probably refers to A. Mentz114's recent post refers to C, which encapsulates the principle of relativity. I came up with B on my own.

With D and A you will get that the Earth clock and the ISS clock run at different rates. With B and C you will get that the Earth clock and the ISS clock run at the same rates.

The beauty of GR is that it is a single law of physics which explains A, B, C, and D all together.

Bjarne

Double .

Bjarne

Off course I cannot disagree to that.
I was confused because I thought you did not agree to that, - when times ticks different, in different space-time, then each second also does, - whereby the comparable length off 1 second must be either stretching or shrinking. – So I expected a different kind of answer to your question, not easy to know what that possible could be.