Moving at light speed

[Buffy]

Sounds like you're arguing that the expansion of the universe is the same as being on a moving train, which its not: thats the key to the fallacy. To a local observer, you're not moving, to a distant observer you are, but solely due to the expansion of the universe, not due to relative motion.

 

Cheers,

Buffy

[Damo2600]

If my viewpoint is flawed according the movement of distant galaxies then it would also be flawed according to the movement of the train. Relatively one event appears to be reality, but alas, it is not reality. Then it would be the same for both you see.

 

Relative viewpoints do equal reality because we have no other reference frame. However if we make the expansion of the universe the absolute reference frame, or the centre of our galaxy, we can then derive all reference frames from this point. Therefore we could have absolute time and space.

 

Absolutes, however, have no place in this universe and a gazillion empirical tests have proven this. You want to break the rules, well then, you need to revise them and come up with a new set.

 

I agree it's absurd. But you cannot skirt around the rules as easily as you are attempting to do. *We* have a problem, *you* need to fix it. Ignoring the problem won't make it go away.

 

Damien

[Buffy]

If my viewpoint is flawed according the movement of distant galaxies then it would also be flawed according to the movement of the train. Relatively one event appears to be reality, but alas, it is not reality. Then it would be the same for both you see.

Well, actually no. Relativity says that whatever you observe is relative to you, and indeed others will perceive the same events differently. To me time is slowing down on your train, while it appears normal to me, and vice versa. Both our viewpoints are "reality" even though they don't "agree."

Relative viewpoints do equal reality because we have no other reference frame. However if we make the expansion of the universe the absolute reference frame, or the centre of our galaxy, we can then derive all reference frames from this point. Therefore we could have absolute time and space.

Exactly, which is why there is no absolute reference frame. According to the Cosmological Principle, the Universe is isotropic, which translates into: no matter where you are in the Universe, it looks like You are in the center. The only point I've been making here (which is covered much more lucidly in the SciAm article mentioned above), is that just because the universe is expanding and makes things appear to be moving faster than light, does not mean that they *are* moving faster than light, and in fact by Special Relativity and the Cosmological Principle, we *know* they are not.

I agree it's absurd. But you cannot skirt around the rules as easily as you are attempting to do. *We* have a problem, *you* need to fix it. Ignoring the problem won't make it go away.

Well, I'm really just quoting Special Relativity and generally accepted cosmology, so are you saying that Einstein, was wrong?

 

Cheers,

Buffy

[Damo2600]

Well, actually no. Relativity says that whatever you observe is relative to you, and indeed others will perceive the same events differently. To me time is slowing down on your train, while it appears normal to me, and vice versa. Both our viewpoints are "reality" even though they don't "agree."

Exactly, which is why there is no absolute reference frame. According to the Cosmological Principle, the Universe is isotropic, which translates into: no matter where you are in the Universe, it looks like You are in the center. The only point I've been making here (which is covered much more lucidly in the SciAm article mentioned above), is that just because the universe is expanding and makes things appear to be moving faster than light, does not mean that they *are* moving faster than light, and in fact by Special Relativity and the Cosmological Principle, we *know* they are not.

Well, I'm really just quoting Special Relativity and generally accepted cosmology, so are you saying that Einstein, was wrong?

 

Cheers,

Buffy

 

No. It is YOU who is claiming Einstien to be wrong. Plus you are contradicting yourself. According to *me* said galaxy is moving at c and that is reality. According to *you* said galaxy is NOT moving at c and that is reality. How can both realities be true yet *your* reality be truer than *mine*. It's absurd.

 

Don't you think?

This is the last attempt I'm making. Beyond that this conversation is becoming absurd.

 

Damo

[Buffy]

No. It is YOU who is claiming Einstien to be wrong.

Not at all. Sounds like we're in violent agreement that Einstein is correct! The only question I'd have is that you seem to be claiming that its possible for objects to travel at the speed of light, which Einstein does say is not possible.

Plus you are contradicting yourself. According to *me* said galaxy is moving at c and that is reality. According to *you* said galaxy is NOT moving at c and that is reality.

Sounds like you're just missing the distinction here: We all know that an object cannot travel at the speed of light because it would take infinite energy to do so, which does not exist in the universe. No mass can travel at the speed of light. It can *appear* however that something distant is moving away at approaching and up to what we *measure* as the speed of light because the *distance* is expanding, thus distorting our measurements.

Don't you think? This is the last attempt I'm making. Beyond that this conversation is becoming absurd.

Well I don't think you should take my word for it: the SciAm article explains this all very well.

 

Cheers,

Buffy

[Damo2600]

Not at all. Sounds like we're in violent agreement that Einstein is correct! The only question I'd have is that you seem to be claiming that its possible for objects to travel at the speed of light, which Einstein does say is not possible.

Sounds like you're just missing the distinction here: We all know that an object cannot travel at the speed of light because it would take infinite energy to do so, which does not exist in the universe. No mass can travel at the speed of light. It can *appear* however that something distant is moving away at approaching and up to what we *measure* as the speed of light because the *distance* is expanding, thus distorting our measurements.

Well I don't think you should take my word for it: the SciAm article explains this all very well.

 

Cheers,

Buffy

 

I love how you missed a sentence in your quotes.

 

If it doesn't fit in the box we'll squash it in.

 

Damien

[Buffy]

I love how you missed a sentence in your quotes.

If it doesn't fit in the box we'll squash it in.

Please don't take offense at this: Its actually recommended by the Hypography FAQ which you might want to take a look at:

Please consider editing the quote so that only so much of the previous posts that you feel is necessary for users to follow the thread is included. Very long quotes should be broken up or edited before you post them. Remember that quotes take up a lot of space in our database so keep them short. A long quote with a one-line reply is considered bad form.

It shouldn't be assumed to be "misquoting." Interested parties can always go back and view the full quotes.

 

Cheers,

Buffy

[Damo2600]

Hey the time on the train appears to be different. The movement of the train is distorting our measurements. Time is not really slower.

 

Push it in the box.

[Buffy]

Hey the time on the train appears to be different. The movement of the train is distorting our measurements. Time is not really slower.

I guess you're trying to prove that I'm saying something that violates SR, which I'm not. SR is often explained in terms that assume rough locality of the relative observers, in which case the expansion of the Universe is negligible. When relative observers are separated by distances encompasing nearly the size of the Universe, measurements do indeed need to be adjusted for the effects of expansion, and this does not violate SR. If the converse is true, then the measured speed of those distant galaxies is c, which SR says is impossible.

 

Cheers,

Buffy

[paultrr]

Do we know any galaxies even appearing to recede close to the speed of light?

 

I can stand to be corrected on this. But by redshift I think the fastest known is about 90% of C relative to us. Its also true that this is a visual effect brought about by the expansion of the cosmos and that their own local velocity is way below that frame to frame one.

[Damo2600]

Well my relative veiwpoint is incorrect. I see. No matter which reference point I am viewing the world from it is not right and I should therefore consult Buffy for the correct viewpoint. You will do this by wieghing up all the reference frames and deciding which is the best for me. Yours IS the absolute. I hope you will be available for this. Should I make an apppointment now? Weddings, Parties, Anything. You may make a fortune.

 

D :eek:

[Buffy]

Well my relative veiwpoint is incorrect. I see. No matter which reference point I am viewing the world from it is not right and I should therefore consult Buffy for the correct viewpoint.

Gee whiz dude, I said don't believe me if you don't want to, just read the article...if you're saying what I've said here is wrong, then you're saying that Scientific American publishes incorrect theories, because all I've done is repeat the content of the article. All that can be concluded from your posts is that you do believe that a mass can be accellerated to the speed of light, and not many people will agree with you on that.

 

Cheers,

Buffy

[cindy 2005]

Is the following statement true. If no why?

 

When a body with mass m0 moves at light speed his energy is infinity.

 

E = mc^2 = m0 * c^2 / sqrt ( 1 - c^2 / c^2) = m0 *c^2 / 0 = infinity

 

I know it's impossible for a body with mass to reach that speed, this is a theoretical question.

 

 

I am not quite sure to understand your post. However, I consider the Einstein formula cannot be applied in your case. This formula is used only when we know that the "state" of object is already in the speed of light. In that case, the mass m0 approaches to 0. Thus, 0/0 is sometimes not an infinity because the limit of math form of 0/0 may exist in some cases. Therefore, I can say that the energy E cannot be infinity but it has to converge to a big number (constant). We already know that no objects can move faster than light. But it may not be true because scientists are questioning about it after a series of discovery about light in recently years.

[Damo2600]

Rather than go back and give lecture on relativity I'll see if I can salvage this conversation.

 

Now the galaxy appears to be travelling at c. Right? If we were unaware of the universe expanding we would see this to be true. Right? For someone between here and the galaxy it appears to be travelling at less than c. Right? But from our point of view the galaxy IS moving at c. Right?

 

The galaxy itself is unaware that it is moving at all. Right?

 

If we consider our viewpoint to be correct, as stationary, the whole universe is revolving around us. right? But that's not how it happens. Any planet would also have this same impression. Right? So we realise that we are revolving around the sun a long way from the centre of the galaxy. Right?

 

Now here is where the problem lies?

 

We can calculate speeds according to various viewpoints: that particular galaxy is receding at a velocity relative to my velocity. We know that you can't add velocities to obtain the speed of light as well (you missed that fact). Time dilation at the speed of c asserts that t does not equal t'. Right? But, if we consider the expansion of the universe, then our galaxy and the galaxy travelling at c maybe travelling at an equal speed away form each other. Therefore our time would really equal theirs but we would view their time to be pushed all the way to the limit at c.

 

So, here we have, from one set of figures their is no time dilation and from another set of figures we obtain infinite time dilation. Right? *Yours* and *mine* respectfully. Now if we use the example of the train. We get a set of figures on time dilation based on the viewpoint of the stationary observer and a set of figures relative to the expansion of the universe. Right? These two sets of figures would also not be equal. Right?

 

We previously have made the correct point of view as the expansion of the universe (Based on the fact that we know in which direction the universe is expanding). Then our set of figures based on the velocity of the train is also incorrect. We must re-evaluate the figures based on the expansion of the universe. Right? So here we've found an absolute reference frame that all other frames can be accurately recorded from. Right?

 

We can now know whether two events are happening simultaneously. We can now know the exact size of masses. We can now know the exact time of any event. We can now set our clocks by the universe.

 

The trick is we now need to work out the exact velocity we are moving away from the centre of the universe. That would equal v. Now if we could generate enough power to move an object to the velocity W where W = c - v. IF we calculate the direction of this object, to be moving in the same direction as the expansion, this object is now moving at c. According to us it is not. According to your absolute reference frame it is moving at c. Thus we are moving fast enough to see it.

 

Using your centre of the universe as the *TRUE* point of reference I can play with relativity aswell. I didn't need to generate infinite energy to do so either.

 

Now you may state that the distance is receding at c and the object is not really travelling at c. But we cannot do this because according to your expanation the centre of the universe is stationary (and absolute). So the centre of the universe is not receding from the object. Do you understand how this works?

 

No absolutes in relativity! Believe authority if you must. But your own mind needs to be considered first.

 

Damien

[Tormod]

I am having problems understanding the issue here. Are you guys debating whether the universe has a fixed center or not? I though it was established that there is no "geographic" center of the universe, since by definition every point in the universe once existed within the "cosmic egg" that caused the Big Bang, which implies that every point can be considered to be the center.

 

This is how I read Damien's post as well.

[Buffy]

You're missing two key points:

1. There is a difference between actual relative motion and the expansion of universe solely in terms of *interpreting* the measured speed. The photons are obeying SR, that's why we don't see things past the Hubble limit, because indeed you *can't* add to the speed of the light that is travelling between here and there.
   
2. This argument is *only* about using these observations to prove that mass can move at the speed of light. The expansion of the universe makes it appear so, but because it is expansion of the universe that is causing this appearance rather than force applied to accellerate the mass, nothing of the sort is shown.
   

None of this argument (and again, its *not* mine, its out of SciAm) requires violation of SR, requires absolute measurements or reference frames, or requires a center of the universe (which would violate the Cosmological Principle). SR was in fact elucidated *before* we understood the expansion of the Universe, indeed we would not have been able to discover the expansion without it! Nothing about expansion invalidates SR, and the only point here is about the interpretation of the perceived data, which in this case involves cosmological distances in which expansion dominates "relative motion." Since SR was described without reference to expansion, it does not say anything specific about it, but at the same time, the existence of expansion does not affect SRs predictions regarding the speed of light or how remote events are perceived. Its the *interpretation* of those perceptions--which SR says *nothing* about--that are being misused to prove silly points like "mass can travel at the speed of light."

Now the galaxy appears to be travelling at c. Right? If we were unaware of the universe expanding we would see this to be true. Right? For someone between here and the galaxy it appears to be travelling at less than c. Right? But from our point of view the galaxy IS moving at c. Right?

We agree on all of this.

The galaxy itself is unaware that it is moving at all. Right?

This is the most important point: to "local" observers, where the expansion of the universe is negligible, its obviously not moving at all, and has had no force applied to it.

If we consider our viewpoint to be correct, as stationary, the whole universe is revolving around us. right? But that's not how it happens. Any planet would also have this same impression. Right? So we realise that we are revolving around the sun a long way from the centre of the galaxy. Right?

All true. However "correctness" is all relative! :eek:

We can calculate speeds according to various viewpoints: that particular galaxy is receding at a velocity relative to my velocity. We know that you can't add velocities to obtain the speed of light as well (you missed that fact). Time dilation at the speed of c asserts that t does not equal t'. Right? But, if we consider the expansion of the universe, then our galaxy and the galaxy travelling at c maybe travelling at an equal speed away form each other. Therefore our time would really equal theirs but we would view their time to be pushed all the way to the limit at c.

Yep, *except* for the word "travelling" in this quote: that's actually the whole point of this exercise. The galaxies are *NOT* "moving" away from each other, the space between them is *expanding*. Again, this is the only point: the galaxies are not "moving" or "travelling" at the speed of light, and that is an incorrect interpretation of all the data which does agree completely with SR.

So, here we have, from one set of figures their is no time dilation and from another set of figures we obtain infinite time dilation. Right? *Yours* and *mine* respectfully. Now if we use the example of the train. We get a set of figures on time dilation based on the viewpoint of the stationary observer and a set of figures relative to the expansion of the universe. Right? These two sets of figures would also not be equal. Right?

This is where you're completely misinterpreting me. I'm not arguing that there's no observed time dilation at all! Thats why the observed spectrums are red shifted and why we can tell how fast its moving in the the first place.

We previously have made the correct point of view as the expansion of the universe (Based on the fact that we know in which direction the universe is expanding). Then our set of figures based on the velocity of the train is also incorrect. We must re-evaluate the figures based on the expansion of the universe. Right? So here we've found an absolute reference frame that all other frames can be accurately recorded from. Right?

Yes, the universe is expanding and yes you do have to make an adjustment for the distance between the two points but this does *not* require an absolute frame of reference! All you have to do is measure the distance using the red shift and use the Hubble constant to figure out what part of the perceived relative motion is accounted for by expansion versus any locally percieved motion! There is no "absolute" speed that is relevant here, the argument has to do with "local" observations: that is, close enough where the speed is mostly accounted for by actual relative motion rather than the expansion of the universe. Again, the perceptions are all the same, its the interpretation that's the issue.

We can now know whether two events are happening simultaneously. We can now know the exact size of masses. We can now know the exact time of any event. We can now set our clocks by the universe.

No, and I think we are agreeing that you can't do any of these things.

<stuff about computing with an absolute reference frame which doesn't exist deleted>Using your centre of the universe as the *TRUE* point of reference I can play with relativity aswell. I didn't need to generate infinite energy to do so either.

We agree, no absolute frame of reference so you can't "play with relativity", but that still means that you *do* need infinite energy to *move*--as opposed to seeing something appear to move due to *expansion*--a mass to the speed of light

Now you may state that the distance is receding at c and the object is not really travelling at c.

Yep. That's exactly the point, and again, is the *only* point. No absolute frame of reference, no violation of SR. It appears to be moving at the speed of light, light gets here in complete agreement with SR--there's no additive effect, the photons going from here to there are travelling exactly c, etc.--but those photons have had to go over a long distance which has been expanding since they left the other galaxy. They keep having to go farther and that increases the *perceived* speed of the other galaxy. In its local frame of reference it is not moving much, has not been accellerated anywhere near the speed of light, and thus it is incorrect to state that because we perceive it as *moving* at the speed of light, that we can interpret that data as showing that it *is* moving at the speed of light, which would require infinite energy, etc.

No absolutes in relativity! Believe authority if you must. But your own mind needs to be considered first.

As I say, I think we're in violent agreement on most all of this. I must say I don't see what your point is other than making the assumption that I'm trying to argue against SR, which I'm not. I go back to my original question to you: are you saying that in the local frame of reference where the expansion of the universe is negligible, is the remote galaxy moving at the speed of light? That's where I think we'd disagree, and that's the key point of the SciAm article, but on just about everything else we do.

 

Cheers,

Buffy

[Damo2600]

There you did it again. You responded to the whole message and deleted the actual point I was trying to make. There may be rules to this group that state you can do this but you've done this to me twice now. You are not the kind of person I would wish to discuss such a complex issue with. Very reactionary and unscientific. Sorry Tormod I'll get back to your message soon. Busy busy busy....