# Galileo & Einstein - second thoughts

Discussion in 'Physics & Math' started by c'est moi, May 12, 2002.

1. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583
"""Just read your last post. I see where you are coming from now. But I'm for home. Catch you later."""

indeed, because from your response I still see that you are thinking on a different thing than me

what I mean is what I have said

I don't know how I have to say it to be more clear

you might want to read the piece where this discussion started with James R in "mass=energy"

3. ### thedIT GopherRegistered Senior Member

Messages:
1,105
Absolutely right.

The first time people see this they generally feel reality shift to the left a little. It sounds ludicrous and it is.

The thing to realise is that special relativity only holds for intertial frames. The ball has accelerated from rest to some speed. Therefore no inertial frame. The ball gains energy.

If this was an inertial frame another thing happens, as you've realised. The amount of energy the Earth would gain appears to be the same of as the ball gets, absolutely negligble for the Earth but a lot for the ball. But in reality there are no real inertial frames. The idea is a simplification, compared to General Relativity, designed to further understanding of how things really work.

Special relativity helps us further our understanding that the Universe is not as simple as Galileo and Newton believed.

It is probably more fair to say the person throwing the ball gains in energy. But again, the ball has accelerated so SR does not hold.

In an ideal, perfect world of constant velocity only this confusion should happen. As you point out it is possible to work out who is really travelling faster. The trick is that you have to sit down and work that out. What students spend a lot of time doing is solving deliberately contradictory problems to see if they can work out which FOR is the best one to solve the problem in.

I hope that helps clear a bit of the mess up without it sounding lke a major kop out. One of the problems when trying to explain this is that everyone falls back onto the standard explanations where they suddenly saw the light for themselves, expecting others to see the light for themselves.

5. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583
okay, if these were inertial frames I would have knocked down relativity

- tell me why relativity only holds for inertial frames
- what, then, are indeed inertial frames (cite some examples)
- also, tell me what happens in regard to the observer with his clocks, i.e. he has been accelerated yet relativity is used there with time dilation as a result. He is just like the ball which has been thrown away.

7. ### thedIT GopherRegistered Senior Member

Messages:
1,105
You wish

If the Universe contained nothing but two observors moving at two differing yet constant velocities all they can work out is the difference in velocity. But the Universe is vastly more complex than that. Most things are at rest with respect to light, in their own frames, you need some seriously wierd conditions to get two observors, travelling near light speed, to compare conditions. This is where high energy Astrophysics comes in as a serious test of Relativity. In reality light travels at light speed, we are effectively stationary.

The trick is knowing where to ignore affects, like our motion with respect to a far distant observor.

It's an assumption, an axiom, of Special Relativity. General Relativity holds for accelerating frames.

All that is required is that the derived results of those assumptions be shown to be wrong for Einsteins ideas to be knocked down. So far they have held.

Simply put, a frame moving with constant velocity.

But in the real world most frames, observors, are in gravitational fields so feel acceleration. They are non-inertial frames. Normally the gravitational field is so weak it can be assumed to be an inertial frame though. In physics this is referred to a Lab frame. Your measurements are taken over a small enough scale the affects can be ignored.

As I say, for every day events Galilean transforms hold. Only when the other frame is moving signicantly faster than you, near light speed, compared with your stationary frame, does Special Relativity hold.

I suppose that is the big thing. The relative speed has to be huge, us 'stationary' and the object near lightspeed compared to us for Relativity to be invoked.

Same thing I suppose, if the two observors have a huge velocity difference, the higher one has a larger time dilation compared to the lower one. Technically, if you have two observors at light speed they see the same thing, no time dilation between them.

Hope that helped.

8. ### thedIT GopherRegistered Senior Member

Messages:
1,105
C'est Moi

Just realised something. The whole point of Relativity is the difference in velocities.

The way I personally look at it is that light speed is the base line and you calculate effects based on your difference to that. To all affects and purposes if I throw a ball into the sky it only has kinetic energy KE= 1/2 mv^2, it's speed is not enough to take SR into account. Strictly speaking you should but the afects are so small you can not measure them. Only for a near light speed particle is the effects significant, compared to us.

Of course, there are complicating factors such as strong gravitational fields and large distances. Again, the invariance of light speed is taken to be a local affect. Local being the scale of the Uinverse. But if you have something 12 billion light years away in a strong gravitational field these simplistic assumptions of SR just do not hold.

9. ### Adam§Þ@ç€ MØnk€¥Registered Senior Member

Messages:
7,415
I've gotta say, I can't yet see one point in this.

If you shine torches in directly opposite directions, one in each hand, away from you, the light is shooting off ine either direction at C. The distance between the leading edges increases at a rate of twice C. I can not see how that would be otherwise. C remains a constant, but their relative motion seems double C to me.

10. ### James RJust this guy, you know?Staff Member

Messages:
37,550
c'est moi:

Let's take a look at your baseball throwing example.

<i>using the rel. principle: or it is the ball which is going up away from the earth or it is the earth which is moving away from the earth, no preferred FOR</i>

Either point of view is fine, but it turns out to be MUCH easier to take the baseball to be moving. The reason is that in that case the Earth can be taken to be an <b>inertial</b> frame of reference. An inertial frame of reference is one which is moving with constant velocity and not accelerating. The Earth actually accelerates a tiny bit when you throw the baseball, but we can ignore that because the Earth is so much more massive than the baseball. On the other hand, the baseball's reference frame is definitely non-inertial. It accelerates constantly throughout its motion. That complicates the analysis considerably, as I will explain below.

<i>we do, however, speak in terms of measuring the kinetic energy of that ball which has been provided by your arm

BUT, from the other point of view, it is the earth who is flying away, at let us say 60 miles/hour obviously, the earth must aquire kinetic energy seen from the FOR of that ball</i>

<i>1) the energy has been provided by my body and transferred to that ball...and didn't go to the earth where does the earth get its kinetic energy?</i>

Let's be very careful with reference frames. In the Earth frame, the energy of your arm was transferred to the ball, which therefore acquired kinetic energy. In the reference frame of the ball, the energy of you arm was transferred to the Earth, which acquires kinetic energy.

In the reference frame of the Earth, the only forces acting on the ball are your arm throwing it and gravity pulling it down. But in the ball's reference frame things are different. We have you arm throwing the Earth away and the ball's gravity attracting the Earth back to it. But, because the ball's reference frame is non-inertial we also see an inertial force due to the reference frame, which accelerates the Earth more rapidly than we would otherwise expect. This force initially helps accelerate the Earth away from the ball, then it changes direction to help accelerate the Earth back towards the ball. The force is real from the ball's point of view, but imaginary from the Earth's point of view. It can be shown to arise solely due to the change of reference frame.

Without the extra inertial force, the principles of conservation of energy and momentum do not hold in a non-inertial reference frame. That is why relativity is formulated in inertial reference frames.

Therefore...

<i>2) the very thought that we speak about measuring or calculating kinetic energy of a moving entity from our FOR is against relativity</i>

is wrong. You can do it if you like, but you have to be careful.

<i>Someone with an atomic clock is moving at an important fraction of the speed of light and passes by us.
what does relativity has to say on this:
--> From our FOR his clock runs slower
--> From his FOR our time (clock) is running slower</i>

That's completely correct. You conclude from that:

<i>...you CANNOT explain this slowing down of his clock due to kinetic energy.</i>

Again, that is correct. The slowing of the clock is due to the different reference frames only.

<i>BUT when talking about clocks moving at high velocity, suddenly, you are not allowed to consider the effects of absorbed kinetic energy (or even gravitational energy) and you are not allowed to explain time dilation nor lenght dilation as a logic consequence.</i>

You can consider energy if you like, but energy is relative. Time dilation and length contraction are not due to changes in energy. They are due to changes in reference frame.

<i>Instead, you have to use the magic of FOR's which is clearly not a true principle of Nature but a fairy tale.</i>

I find it surprising that you are so ready to criticise relativity when it is clear that you do not understand it. Before you can say what is wrong with a theory, you need to know what the theory says.

11. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583
Thed

"""It's an assumption, an axiom, of Special Relativity."""

The axiom arised because it is based on the constant speed of light (hence no acceleration)?

+

has ANYONE an idea how it is possible that photons are not influenced by the speed of the frame from which they have been emitted

photons have moment, right? the atom is moving at 100 km/h and emits a photon forwards
how is it possible for the photon which HAS momentum not to absorb the momentum of the atom? Any idea?

"""All that is required is that the derived results of those assumptions be shown to be wrong for Einsteins ideas to be knocked down. So far they have held."""

I have the feeling that the only thing that FOR's stuff does is complicate things where it can be done more easily. See further.

"""I suppose that is the big thing. The relative speed has to be huge, us 'stationary' and the object near lightspeed compared to us for Relativity to be invoked."""

and,

"""Same thing I suppose, if the two observors have a huge velocity difference, the higher one has a larger time dilation compared to the lower one."""

1) and any gravitational effect can be ignored than?

2) can also be ignored the fact that the object is accelerating towards C and does not have a constant velocity?

12. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583
James

"""Either point of view is fine"""

Thed said that SR does not apply here.

"""but it turns out to be MUCH easier to take the baseball to be moving."""

maybe you should consider the possibily that ONLY the baseball is moving as a consequence of me throwing it away
that's what I mean when I feel FOR's stuff is complicating things which are already complicated as they are

''''"In the reference frame of the ball, the energy of you arm was transferred to the Earth, which acquires kinetic energy."""

in concrete terms, how was the energy transferred to the earth and not to the ball?

"""In the reference frame of the Earth, the only forces acting on the ball are your arm throwing it and gravity pulling it down. But in the ball's reference frame things are different. We have your arm throwing the Earth away and the ball's gravity attracting the Earth back to it."""

and this is where FOR's become silly: I have to believe that my arm throws the earth away
moreover, aren't you wrong here? after all, Thed said that SR does not apply to this scenario because that ball is accelerating all the time

"""But, because the ball's reference frame is non-inertial we also see an inertial force due to the reference frame, which accelerates the Earth more rapidly than we would otherwise expect. This force initially helps accelerate the Earth away from the ball, then it changes direction to help accelerate the Earth back towards the ball. The force is real from the ball's point of view, but imaginary from the Earth's point of view."""

it is imaginary
look, I trow the ball let us say 20 metres in the air, or no even more , i'm strong and I throw it 150 metres in the air
Now, I have to believe that from the FOR from the ball that my arm has trown away the earth 150 m in the opposite direction
Believe me, this doesn't happen.

"""It can be shown to arise solely due to the change of reference frame."""

it cannot be shown because I said earlier, SR has only been tested in a one-way direction
the rest happens in the minds of scientists

"""Without the extra inertial force, the principles of conservation of energy and momentum do not hold in a non-inertial reference frame. That is why relativity is formulated in inertial reference frames."""

I see

"""Again, that is correct. The slowing of the clock is due to the different reference frames only."""

Which explanation should be favoured, one which gives a fairly simple reason like increase in kinetic energy or one which basically toys around with FOR's with no physical explanation? Which one deserves to be favoured by Occam's razor? Which one needs to be favoured, the one which claims both ways are equal but has only been tested in one way or the one which cuts the imaginary frame away and can succesfully be confirmed in every single experiment (lorentz equation are correct)?

"""You can consider energy if you like"""

indeed, I like that more

"""I find it surprising that you are so ready to criticise relativity when it is clear that you do not understand it. Before you can say what is wrong with a theory, you need to know what the theory says."""

i feel that after these discussion I do know what it says
it says everything is relative

it moves you around in frames explaining that no effect is actually real like real for everyone but just side effects of your perception
in that way it creates an explanation which does not even try to explain the effects as result of mechanisms in nature
I feel the latter deserver to be favoured unless it can be shown that SR is real in both ways instead of keeping the other way imaginary

13. ### Adam§Þ@ç€ MØnk€¥Registered Senior Member

Messages:
7,415
Heck, even I know why photons (measurement units of EM signal) have a given speed regardless of the motion of the emitter (I think I do anyway!). Light is a propagation of EM energy through space/matter. That propagation depends on what it is travelling through. Change the medium, the speed of propagation changes. But the light itself does not change depending on the medium or the emitter. Why?

I used an analogy a while ago, involving running in water. If you run at your full speed in water, you basically run at your top speed reduced by the material of the water dragging on you. Light=runner, space=water. If you jump out of a car speeding along the beach and land in the water and run, you will still only be able to run at that running-in-water top speed. The motion of the car won't change that. (You have to ignore the little bit of time from jumping out of the car to running in the water.)

The running in water is based on your size and cross-section and friction and all, and in particular on the amount of energy you apply and the water as well. Similarly, light propagation is based on the energy involved (runner) and the material (water). The light will not be able to move faster if the torch it comes from is hurtling along the beach in a car.

The propagation of light depends only on the energy involved and the space/material it is passing through. Or at least that's how it seems to this uneducated person.

14. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583

"""If you jump out of a car speeding along the beach and land in the water and run, you will still only be able to run at that running-in-water top speed. The motion of the car won't change that. (You have to ignore the little bit of time from jumping out of the car to running in the water.) """

you example is insisting that photons move true a medium

+

how do you explain with your example that momentum is not conversed in regard to photons

15. ### Adam§Þ@ç€ MØnk€¥Registered Senior Member

Messages:
7,415
Sorry, I can't explain that at all. I have not studied this stuff enough to know anything about conservation of momentum and such. I'll get around to it some day...

16. ### James RJust this guy, you know?Staff Member

Messages:
37,550
c'est moi:

<i>maybe you should consider the possibily that ONLY the baseball is moving as a consequence of me throwing it away
that's what I mean when I feel FOR's stuff is complicating things which are already complicated as they are</i>

Can you give me a test which will tell me whether it is really the baseball or the Earth which is moving? If not, then either point of view is equally good.

<i>in concrete terms, how was the energy transferred to the earth and not to the ball?</i>

Newton's third law says for every force there is an equal and opposite force. Therefore, when you exert a force on the ball to throw it, the ball exerts an equal force on you in the opposite direction. That reaction force causes you to accelerate, taking the Earth with you (since you're standing on it).

<i>and this is where FOR's become silly: I have to believe that my arm throws the earth away moreover, aren't you wrong here? After all, Thed said that SR does not apply to this scenario because that ball is accelerating all the time.</i>

Ignore whether SR appies or not and use your common sense. What do you see from the ball's point of view? You see the Earth moving away. Therefore, something must cause it to move away. That requires a force, and that force can only come from your arm.

<i>Now, I have to believe that from the FOR from the ball that my arm has trown away the earth 150 m in the opposite direction
Believe me, this doesn't happen.</i>

Why not? If you say it doesn't happen you need a reason for that belief other than just your gut feeling.

<i>Which explanation should be favoured, one which gives a fairly simple reason like increase in kinetic energy or one which basically toys around with FOR's with no physical explanation?</i>

A FOR is a physical explanation. And your kinetic energy arguments do not cut the mustard, whereas relativity has been rigorously tested and shown time and again to work.

<i>...it moves you around in frames explaining that no effect is actually real like real for everyone but just side effects of your perception</i>

No, that's not true. Effects are real. Certain physical quantities are invariant in different reference frames. It's just that you insist on looking at quantities which vary in different reference frames.

<i>I feel the latter deserver to be favoured unless it can be shown that SR is real in both ways instead of keeping the other way imaginary</i>

SR is real in "both ways". It has been tested.

17. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583
The mystery was cleared up, falsification was the problem all along ...

"""Can you give me a test which will tell me whether it is really the baseball or the Earth which is moving? If not, then either point of view is equally good."""

From the point of view from the ball, if that baseball has brains, it will think "Aha, I am the one flying away from the earth".
It seems that all of you assume that once you take the FOR of something, that that's the one who should be regarded stationary and the other one moving. That's absurd. In fact, both are moving. The earth around the sun and the ball away from the earth.

Further, can you provide me an experiment that will affirm me that the universe is not mere a dream or an illusion. I guess you can't do that so now everybody has to accept that everything is an illusion....

That's also a problem with relativity, and I will say this again and again, it can only be tested in one way. Further, imagine you fly away with that ball with all the equipment that you can imagine. what will you be able to do in order to see if it is really you who is moving? What is there to measure? Aah, you say it yourself, no experiment can be found for this ... what does this mean, IT MEANS THAT WITH THE PRINCIPLE NO FALSIFICATION IS EVEN POSSIBLE ... Popper is looking really really mad here.

"""Newton's third law says for every force there is an equal and opposite force. Therefore, when you exert a force on the ball to throw it, the ball exerts an equal force on you in the opposite direction. That reaction force causes you to accelerate, taking the Earth with you (since you're standing on it)."""

When I push against a wall and I push so hard that I get through it with my arms, then the bricks are falling out on the ground on the other side. It is not the earth and me who are falling up. If so, we all should feel this on earth. If the earth is flying away 150 metres from the baseball, everyone should feel this. Teuuuuuuuut teeeeeeeuut::: let me correct myself: we cannot feel this because that is the way it is for those bricks and that wall. Not for us....... Silly old me. ---> no falsification is possible (this is really striking me and hopefully you also).

"""Ignore whether SR appies or not and use your common sense."""

I can't do that if I believe in SR principle.

"""What do you see from the ball's point of view? You see the Earth moving away. Therefore, something must cause it to move away. That requires a force, and that force can only come from your arm."""

You see that YOU leave the earth BEHIND. Bye bye earth. "I am moving also from my point of view", that's what you think. I realise this. Wow. Going fast here ........ ........... weeeeehaaaaaaaaaaaaa!!! Oeps, something has happened: Everything went dark ..... what to do? The only things I can see is my own body and the earth. Oh my God!!, no reference is possible: Who is moving??? All my information has been taken away. Well, let's not get silly and panick here and let us realise that without more information I'll not be able to tell who is moving.

"""Now, I have to believe that from the FOR from the ball that my arm has trown away the earth 150 m in the opposite direction
Believe me, this doesn't happen.

Why not? If you say it doesn't happen you need a reason for that belief other than just your gut feeling.""""

I'll tell you something new here (haha), falsification is not possible and that's why. I also tell you, there's some pink elephants walking around here in my room. the problem is that you can only see them if you are here in my room. If you are outside the room, you can't see them. that's not all: If you come in my room to look at them, they'll be outside the room and again, you won't see them. You have to go outside the room for that ..... you know the rest don't you?

"""A FOR is a physical explanation. And your kinetic energy arguments do not cut the mustard, whereas relativity has been rigorously tested and shown time and again to work. """

it seems to me that you are not following here: EVERY test that has been tested to test relativity has been testing it in ONEEEEEE WAAAAAAAAY. (btw, one way). And every single test also confirms that these effects can be due to kinetic energy or grav. energy. That is the mechanism where falsification is possible. But as it seems to agree with all experiments so far, it seems to be correct. We simply cut away the other FOR of reference because

1) it is not even usefull to us
2) no falsification is possible

Simply --> Lorentz equations remain, intepretation lil different and the mechanism behind the changes is explained (you can look up the papers of Marmet, it agrees fully with what we see, the only thing that is different is the mechanism behind it)

"""...it moves you around in frames explaining that no effect is actually real like real for everyone but just side effects of your perception

No, that's not true. Effects are real. Certain physical quantities are invariant in different reference frames. It's just that you insist on looking at quantities which vary in different reference frames."""

sometimes you should read something twice, ie I say "no effect is actually real <<like real for everyone!!>>

"""SR is real in "both ways". It has been tested."""

In your dreams apparently. One way. Not two ways. Two ways is impossible as the Pink elephants (read 'the principle itself') show us.

I guess you've flied on an electron at 99,999 % of c and that whilst going so fast, you've actually been able to see that my clock down there was going slower. Moreover, you felt nothing special at that speed because we are taking you as a FOR here and the rule says: The one who is taken as FOR must be the one who is regarded stationary. Moreover, you've not accelerated at all. Yep, that's right. You went all the way up to 99,9 % of c without acceleration. Indeed, relativists regard you as an inertial frame.

I'll tell you what happens when you go so fast:

First of all, you'll get the effect like looking at the wooden beams connecting the railways --> when the train goes fast, you'll be able to see each individual, but when it goes 80 km/hour you'll see all of them like one piece
If you go even more faster on that e-, you practically see nothing: just colours and shapes, maybe not even shapes
if you're not dead already, you'll realise that you're going fucking fast, everything will flash before you eyes, it would be like madness ... and this sightseeing of yours won't change wether you're stil accelerating or not.
if you fly with an airplane at a few Mach's without accelerating, you still won't be able to count any of those wooden beams if you'd fly over them. you'd be able to walk around without falling but that's all.

18. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583
LEt us keep this one up

up

19. ### James RJust this guy, you know?Staff Member

Messages:
37,550
c'est moi:

I asked: <i>Can you give me a test which will tell me whether it is really the baseball or the Earth which is moving? If not, then either point of view is equally good.</i>

You replied: <i>From the point of view from the ball, if that baseball has brains, it will think "Aha, I am the one flying away from the earth". ... It seems that all of you assume that once you take the FOR of something, that that's the one who should be regarded stationary and the other one moving. That's absurd.</i>

So, I take it your answer is "No, I can't give you any test which can distinguish between the baseball moving or the Earth moving." It's just your gut feeling that's driving your argument - nothing more.

<i>Further, can you provide me an experiment that will affirm me that the universe is not mere a dream or an illusion. I guess you can't do that so now everybody has to accept that everything is an illusion.... </i>

No. The correct conclusion to draw is that the universe <b>might</b> be an illusion. But since that fact would have no impact on our perception of the universe, it is ruled out by Occam's razor. On the other hand, if an absolute frame of reference existed it would have certain measurable consequences. Those consequences not being observed, we must conclude that there is no such absolute frame.

<i>That's also a problem with relativity, and I will say this again and again, it can only be tested in one way.</i>

And you will continue to be wrong again and again. The Earth moves around the sun, changing direction all the time. Yet if we do the same experiment at intervals of six months we get the same result, even though the Earth is moving in the opposite direction. That fact alone shows that all inertial reference frames are equivalent. There is no aether to provide an absolute standard of rest. The change in reference frame also tests relativity "both ways".

Also, all relativistic explanations work from both reference frames involved. The Twin paradox can be equally analysed either from the Earth frame or the traveller's frame. The decay time of muons can be measured either from the Earth frame or from the muon's frame and the results are consistent with what is observed - that muons can reach the ground from the upper atmosphere despite the fact that they should decay before they reach the ground if relativity was wrong.

<i>Further, imagine you fly away with that ball with all the equipment that you can imagine. what will you be able to do in order to see if it is really you who is moving?</i>

Nothing. That's the point of relativity. There is no "who is really moving". That implies an absolute frame of reference.

<i>IT MEANS THAT WITH THE PRINCIPLE NO FALSIFICATION IS EVEN POSSIBLE </i>

Falsification of relaitivity could take place in any number of ways. If the predicted advance in the perihelion of Mercury did not match the observations, or the lifetimes of muons did not match predictions, or we observed massive objects travelling faster than the speed of light, or binary pulsars did not lose energy due to gravitational radiation, then relativity would be falsified.

<i>When I push against a wall and I push so hard that I get through it with my arms, then the bricks are falling out on the ground on the other side. It is not the earth and me who are falling up.</i>

From the point of view of the bricks pushed out of the wall it is.

<i>If the earth is flying away 150 metres from the baseball, everyone should feel this.</i>

Do you feel yourself to be rotating at 1000 km/hr? No? Well, relative to the Earth's centre you are. Same reason for the baseball example.

<i>I also tell you, there's some pink elephants walking around here in my room. the problem is that you can only see them if you are here in my room....</i>

Can I do quantitative measurements to show that your pink elephants exist or do not exist? I can to show that relativity exists.

<i>...every single test [of relativity] also confirms that these effects can be due to kinetic energy or grav. energy.</i>

You are wrong on that point.

<i>Simply --> Lorentz equations remain, intepretation lil different and the mechanism behind the changes is explained (you can look up the papers of Marmet, it agrees fully with what we see, the only thing that is different is the mechanism behind it)</i>

Marmet's physics has flaws in it. It cannot replace relativity, since it does not match the observations we make. It is no substitute.

<i>I guess you've flied on an electron at 99,999 % of c and that whilst going so fast, you've actually been able to see that my clock down there was going slower.</i>

No. But I've "flied" (metaphorically speaking) on an aircraft with an atomic clock in it which observed that effect. That experiment was peer reviewed and published.

<i>Moreover, you've not accelerated at all. Yep, that's right. You went all the way up to 99,9 % of c without acceleration.</i>

Nobody ever said you can get to 99.9% of the speed of light without accelerating. I don't know where you get that idea from.

<i>Indeed, relativists regard you as an inertial frame.</i>

An accelerated frame is, by definition, non-inertial. I suggest you find out what is meant by that term.

<i>First of all, you'll get the effect like looking at the wooden beams connecting the railways --> when the train goes fast, you'll be able to see each individual, but when it goes 80 km/hour you'll see all of them like one piece</i>

That's a problem with the processing rate of your eye, nothing more.

<i>If you go even more faster on that e-, you practically see nothing: just colours and shapes, maybe not even shapes
if you're not dead already, you'll realise that you're going fucking fast</i>

How will I know I'm going f**ing fast? How will I know that it's not everything moving past me f**ing fast? Oh, sorry, I asked that before and you couldn't answer.

20. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583
James R, I see that your brain lacks insight on the point of falsification. You just don't get it (now I know you'll tell me that I don't understand relativity ....).(and the measurements are not in both ways) I'll reply later if I feel like it, it's fucking good weather overhere now

21. ### John Devers(AVATAR)Registered Senior Member

Messages:
120
<FONT COLOR=red>Can you give me a test which will tell me whether it is really the baseball or the Earth which is moving? If not, then either point of view is equally good. </FONT>

JR, could the CBMR be used to do this?

Or how about lining the edge of the ball up with the edge of the moon and the horizon of the Earth with the edge of the moon?

22. ### c'est moiall is energy and entropyRegistered Senior Member

Messages:
583
"""No. The correct conclusion to draw is that the universe might be an illusion."""

So let me put it also like that: *Maybe* it is like that from the ball's FOR.

"""On the other hand, if an absolute frame of reference existed it would have certain measurable consequences."""

why do you keep talking about an absolute frame of ref.? we are not discussing that
It is not because we reject the rel. pr. that we have to adopt an abs. F.O.

"""The Earth moves around the sun, changing direction all the time. Yet if we do the same experiment at intervals of six months we get the same result, even though the Earth is moving in the opposite direction."""

I have no idea what you are saying here. The earth never moves in the opposite direction.

"""That fact alone shows that all inertial reference frames are equivalent. There is no aether to provide an absolute standard of rest. The change in reference frame also tests relativity "both ways"."""

stop going towards the aether
we are talking about FOR's in the view of rel.
the change in FOR is always pure maths
basically, you just tell the exact SAME story but you change the FOR in your sentences
one way

"""Also, all relativistic explanations work from both reference frames involved. The Twin paradox can be equally analysed either from the Earth frame or the traveller's frame."""""

wooooooooooooooooow, amazing evidence here- ---> a gedanken experiment

"""The decay time of muons can be measured either from the Earth frame or from the muon's frame and the results are consistent with what is observed"""

You haven't flown together with a muon and shown that our time on earth went slower from that FOR

"""that muons can reach the ground from the upper atmosphere despite the fact that they should decay before they reach the ground if relativity was wrong."""

one way one way one way one way

it has to do with grav. energy

I said: Further, imagine you fly away with that ball with all the equipment that you can imagine. what will you be able to do in order to see if it is really you who is moving?

"""Nothing. That's the point of relativity. There is no "who is really moving". That implies an absolute frame of reference."""

I didn't have to type anything again, it already stands here::

IT MEANS THAT WITH THE PRINCIPLE NO FALSIFICATION IS EVEN POSSIBLE

"""That implies an absolute frame of reference"""

I don't think so. You just have to see every scenario apart. You have huge systems in the universe who have particular directions and starting from that view, if you'd have enough information on all of them, you can work your way out in finding out who is moving towards where, yes, relative to those systems
and who is really moving from all those systems? they are all moving, each one of them

You cannot see the Pink elephants because the principle implies that, yet you are told that they MUST be there. You can't show in an experiment who is moving yet all experiments support the principle .... what a flawed logic.

"""Falsification of relaitivity could take place in any number of ways. If the predicted advance in the perihelion of Mercury did not match the observations, or the lifetimes of muons did not match predictions, or we observed massive objects travelling faster than the speed of light, or binary pulsars did not lose energy due to gravitational radiation, then relativity would be falsified.""""

--> Lorentz equations are used by relativity
we can use these equations for different interpretations

""or we observed massive objects travelling faster than the speed of light""

according to the big bang th. this is happening (oeps, it is space itself that is doing that so no motion involved, yeah right)

"""From the point of view of the bricks pushed out of the wall it is."""

doesn't make sense any sense, it is not guts here, it is logic that is in danger

that's the trick: for the brick, the earth and us are falling up
then a logic person says: hey, that's not possible, we should feel that
smart einstein devotee: ONLY from the FOR from the brick this is happening so from Our FOR you cannot feel this

waw, I am impressed by this kind of nonsense.

""do you feel yourself to be rotating at 1000 km/hr?"""

-> is constant, if the rot. would accelerate you'd fall of your chair

"""Can I do quantitative measurements to show that your pink elephants exist or do not exist? I can to show that relativity exists. """

one way one way one way + Lorentz equations are correct

"""You are wrong on that point. """

"""Marmet's physics has flaws in it."""

Yes, you told me that before. Let me see, what was the argument again in that other thread, oh yes: it is not in accordance with the principle of rel.
Again, I'm impressed by that.

"""since it does not match the observations we make."""

yes it does
equally, mercurius' orbit is easily explained

"""No. But I've "flied" (metaphorically speaking) on an aircraft with an atomic clock in it which observed that effect. That experiment was peer reviewed and published."""

Have they observed that the clocks on earth went slower for the pilots?

"""Nobody ever said you can get to 99.9% of the speed of light without accelerating. I don't know where you get that idea from."""

well, I've been told SR only accounts for inertial frames which means NO acceleration

I said: First of all, you'll get the effect like looking at the wooden beams connecting the railways --> when the train goes fast, you'll be able to see each individual, but when it goes 80 km/hour you'll see all of them like one piece

""That's a problem with the processing rate of your eye, nothing more.""

well my friend, isn't that what an observer does? observing and describing what he sees

I said: If you go even more faster on that e-, you practically see nothing: just colours and shapes, maybe not even shapes
if you're not dead already, you'll realise that you're going fucking fast

"""How will I know I'm going f**ing fast? How will I know that it's not everything moving past me f**ing fast? Oh, sorry, I asked that before and you couldn't answer."""

----------------------------------------------------------------------------
first, just this thought:
----------------------------------------------------------------------------
Our solar system + its galaxy is moving in a particular direction, they all have the same momentum.
let us say they move towards direction A.
Now, I come at 99,9% speed of c from direction B (which is the opposite direction) and I fly by the earth towards direction A as well.

SR says that from the FOR of me, it is me who is stationary and it is the earth and its galaxy who are flying at 99,9% of c towards direction B. Now, dir. A is towards expansion and B is the opposite. If we believe the BB, this expansion is a fact and it has a certain direction. Now I have to believe that we are expanding and moving back at the same time.
We interpret the redshift as being Doppler. We see that almost all stars have red shifts. They are all flying away from us. We say that from any star the same thing is seen: red shifts. We say, everyone is flying away from each other seen from any FOR. How can we then believe that because little Me flies by that this whole galaxy must be moving in the opposite direction. It can't be moving in both directions. An observer on another star will tell us that we still have a redshift and that the guy flying by has a blue shift.

-------------------------------------------------------------------------------

Now, how will you know that it is really you who is moving?

When you go to 99,9% of c you will be accelerating all the time. You will feel that you are moving. Even if everything would turn black, you'd still feel it.

If a train is riding 100 km/h at constant speed, would you say that from the FOR of the earth (or stationary person) that it is the earth rotating faster at that exact spot??

I will tell it one more time very clearly what I think:
----------------------------------------------------------------

The principle of relativity IMPLIES itself, that we CANNOT know or test in ANY WAY if it is CORRECT in it's OWN assumption that WE cannot know WHO IS REALLY MOVING.

Do you understand this? No Falsification is thinkable. None. Nada.
All the proof for SR is NOT proof for its principle, it's always one way and it is proof that the Lorentz equations are correct but not proof for the INTERPREATION of the eqautions.

23. ### CrispGone 4everRegistered Senior Member

Messages:
1,339
Some thoughts

Hi c'est moi,

"I have no idea what you are saying here. The earth never moves in the opposite direction. "

I hope we both agree that the earth orbits the sun. In order to "orbit" the velocity vector has to change constantly to maintain the circular/elliptic orbit. In six months from now, the earth's velocity vector will be pointing in the opposite direction it is going now.

"stop going towards the aether. we are talking about FOR's in the view of rel. the change in FOR is always pure maths"

I think you underestimate the importance of frames of reference (FOR). Im my opinion, the relation between different FOR's is the heart of all physics. If we both observe the same experiment, then there must be some way to link the results we both get. Even in our everyday experience, different observers get different results. I'll use the classical train example here. If you drop a penny inside the train, an observer standing in the train will say it fell straight down, and someone observing that experiment next to the railroad will say it fell in a curved way. Since we're both talking about the very same penny dropping - and very important - and that we both assume that the laws of physics are the same for everyone, then there must be some way to relate the results.

First of all, if you assume the laws of physics to be different for two observers, then you can stop reading here. If everybody has his own sets of rules and laws, then there is no possible way that we can ever agree on the results of an experiment (you will firmly believe your measurement because you saw it happen with your own eyes, I will firmly believe what I saw). This is exactly the (Galilei) principle of relativity, and I quote it here for reference:

Galilei principle of relativity:
For an isolated system:
1. One can always find a coordinate system to describe events, this is called an inertial system.
2. Every other coordinate system that moves with a constant velocity with respect to an inertial system, is again an inertial system.
3. The laws of physics are the same for every inertial system.

I can't see why someone would disagree with the first two aspects, in the first point we assume that we can use numbers to label events (which we can call x,y,z,t for example). This is a necessity to link mathematics and the real world. The second point is the definition of an inertial system, and well, a definition is a definition, there is no right or wrong there (perhaps a "useful" or "worthless", but you can never disagree on a formal definition).

Disagreeing with the Galilei principle of relativity is disagreeing with the fundamental building blocks of science: if you cannot use mathematics to describe nature (first point) or if you don't believe there are other FORs (point two), or if you refuse to assume that the laws of physics are the same for everyone, well then there is no point in continuing science. (irony mode on) I guess we better all pack our bags and go watch Jeopardy (irony mode off)

.

Now, for what you said: aether is a very important concept in the idea of FORs, but you have to realise that nowadays the word aether is no longer used as some "medium in which EM waves propagate" but is used as a synonym for "an absolute FOR". You say that disagreeing with the principle of relativity does not necesserily imply the existance of an absolute FOR.

Two remarks: first of all (and I admit this is a stupid remark), if you don't accept the principle of relativity, then there's no such thing as a FOR. But what you probably refer to is, and I quote from your previous post:
That assumes the existance of an absolute frame of reference (or aether as James R called it). When you say that something is moving, you always have to specify what it is moving relative to. There are two options in your reasoning:
• Either you are floating in your spaceship around the earth and you say "hey look, the earth is moving away, and so is that ball James R has thrown up". But then you are talking from your own point of view, your own FOR. But since all FORs are moving, so are you and hence the quest for something that you are moving relative to is started again. You can repeat this argument a couple of times, you'll always end up with the same conclusion: I can see all the other FORs moving, but since I am also moving, what am I moving relative to ?
• Or you assume that there is some kind of absolute, non-moving "something" that always, under all circumstances stands still. This "something" is called the aether. Since the aether is always standing still, all other FORs move relative to the aether.
This is how aether necesserily comes into the discussion.

You say that both are moving, well you are correct if you assume an absolute frame of reference. However, from our point of view, the earth is stationary: we walk on it, and for some magical reason (no magic involved ofcourse) it doesn't move away from our feet. That's because in our daily lives we talk about the FOR of the earth, and the earth is stationary in that FOR. From the point of view of the sun, the earth is ofcourse moving, but then the sun is stationary. An observer on the sun will not see the sun moving away, because by definition, the FOR of the sun is attached to the sun and moves along with it as it circles around the centre of our galaxy.

In the rest of your post, you argue that one cannot predict a result in another FOR if you perform the experiment in your own FOR. Well, because of the principle of relativity (which I hope to have "proven" to be essential for physics above), you can: the laws of physics are the same for everybody, and hence if a penny falls downward here in Belgium, it won't float upward in China if I perform the experiment there.

This example might look silly compared to particles moving at 0,99999999c, but the idea is the same. If you transform an experimental result from one FOR to another, using the idea that the laws of physics are the same for both, then you are forced to conclude all the counterintuitive things that have been mentioned about particles at 0,99999999c.

Well, I can see this one coming from a mile away: you are going to question the mathematical formulas used to transform from one FOR to another. Unfortunately, these transformation rules are deduced immediatelly from the principle of relativity. Because we are going to talk about Lorentz transformations, I should first add that the Galilei principle of relativity I mentioned above is not the principle of relativity used in the Theory of Special Relativity. What Einstein did was simply extend the Galilei principle of relativity:

Einstein principle of relativity:
For an isolated system:
1. One can always find a coordinate system to describe events, this is called an inertial system.
2. Every other coordinate system that moves with a constant velocity with respect to an inertial system, is again an inertial system.
3. The laws of physics are the same for every inertial system.
4. The speed of light is the same in all inertial frames.

Well, the Lorentz transformations are immediatelly deduced from these simple four points. As I mentioned before, I cannot imagine how you would disagree with the Galilei principle of relativity (points 1 to 3), so if you disagree with the Lorentztransformation, then it must be point 4 in the Einstein principle of relativity you don't believe. I'm not going to repeat what has been said quite some times before on this forum, but the absoluteness of the speed of light is an assumption that is backed up by experiments.

Finally you concluded:

"The principle of relativity IMPLIES itself, that we CANNOT know or test in ANY WAY if it is CORRECT in it's OWN assumption that WE cannot know WHO IS REALLY MOVING.

Do you understand this? No Falsification is thinkable. None. Nada.
All the proof for SR is NOT proof for its principle, it's always one way and it is proof that the Lorentz equations are correct but not proof for the INTERPRETATION of the equations."

First of all, the principles that construct a theory can never falsify the theory itself. External theories are required to do that, which is why no falsification is possible from the point of SR. You say that we cannot tell who is really moving, yes that is true and is one of the basic reasons why most scientists don't believe in an absolute frame of reference, or aether. I think I've addressed the absolute/relative FOR issue in enough detail above