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thorkil2
2008-Oct-15, 06:51 PM
For the Moderators: I'm not sure where to put this, as it is not, strictly speaking, a new question. But I made a comment in the Black Hole? thread that ended up in an argument that hijacked the thread. It isn't ATM, and I don't see another easy fit, but feel free to place it where you will if this is inappropriate. I've opened this thread to answer objections raised without taking over Mike842's OP any further than we have already.

I've quoted much of the argument below for background.

I don't see it as strange. For the photon or the wave front, the speed of light is infinite (edit) within that frame of reference (end edit). Zero distance from point a to point b (because it takes zero time to get there). Not hard then to see the Universe as a singularity from that frame of reference.

Ahhhhh, So, when 'science'/we/they/mainstream does the Lunar Ranging experiments, the photon/wave front is traveling 'instantly' to and from the moon??? Either? Neither?

So far as the observer is concerned, no. We measure a finite time of travel. But the photon, in it's own frame of reference, takes zero time to get from any point a to any point b anywhere in the Universe. It is only seen as finite speed from a frame of reference that is not moving at c.

So, when 'science' measures photons to be traveling at a Constant "c", 186,282.40 miles per second, that means that when we send a light signal to the moon, in 1 tenth of a second, that 'wave front' has traveled ~18,628 miles......and will reach the 186,282.40 mile mark in 9 more tenths of a second

SO, how do you explain those photons in your definition outracing the 'wave front' to get to the moon "Instantaneously"/in 0 time?

The zero travel time is only from the frame of reference of the photon, not from your position as a measuring entity. You experience and measure the time it takes for a photon to get from the earth to the moon. From the photon's frame of reference, traveling at c, no time elapses and there is no distance. If you could travel at c, no time would elapse for you either, for any distance traveled. It's a consequence of time dilation. The photon you see takes a finite travel time as you measure it. If you could place a hypothetical clock at the wavefront, traveling with the wavefront, it would take your identical rest frame clock an infinite number of seconds to equal the traveling clock's one second (or any fraction thereof, for that matter). Of course, travel at c is impossible for anything but the photon/light wave, but it still is a definable frame of reference, and what happens there is not the same as what you observe from your rest frame.

To get a clearer picture, try this: You have two identical clocks. One travels at 0.5c, the other remains with you in your rest frame. It will take your clock 1.1547 seconds to equal one second on the traveling clock. At 0.9c, it will take your clock 2.2941 seconds to equal one second of the traveling clock, and the interval grows as the speed increases toward c. At c (if you could achieve c) the difference would be infinite. Length contraction does not apply only to the moving object, but (because of time dilation) to the subjective distance traveled. If you're the traveler, the Universe gets shorter for you as you approach c. Again, if you could achieve c, distance (from your moving frame) would disappear. It would take zero time to get from any point a to any point b in the Universe. That's not ATM; I think you'll find the effect described in any physics book.

To put this another way, for c to be constant, time and space must be variable in the ways noted above.

First of all, THIS is absolutely False!

To make a flat out statement like this is absolutely irresponsible!

"c" can be Constant and Time can be Constant as well as 'Space'.

Not since Newton was expanded by Einstein. In fact, much of the point of SR is that space and time are frame-dependent.

How do you suggest we discuss redshift? Perhaps we call it an instant shift in the energy of the photon, which never had time nor place to gain or lose energy in the first place.

Let's teach it starting tomorrow, sounds like fun.

The only way we can say a photon is instantaneous is if it has an instant effect, which has not been found.

For timb and alainprice--come on, this is text book SR. If you have a complaint, take it to Einstein. The red shift is measured from some relative rest frame. Your measurements are valid from that frame and only that frame. Change frames, and you get different results. I'll say it differently: if I could use the word "experiences" loosely in this context, for lack of a better word, I would say the photon "experiences" no elapsed time from source to destination. That has nothing to do with what you measure because you are doing the measuring from a different frame of reference. It isn't instantaneous from any frame of reference you have access to, so no, there won't be instant effect. To the photon, however, the effect is instantaneous. Different frames of reference. Now, I've been dealing with this for 50 years, but I won't make you take my word for it. A quote from Paul Davies (Professor of Natural Philosophy at the University of Adelaide in Australia at the time this was written) in his book "About Time" (1995), p.190:

From the point of view of the [light] pulse, no time at all elapses as, in our frame of reference, it sweeps across the solar system.

Will that do, or do I need to dig out more references?

SO, when we send a light beam to the moons reflector (Let's assume for ease that the moon is exactly 186,282.40 Miles) we wind up with 2 maths for the 'same' beam IE; that beam is both traveling at "c" and takes one second to reach the moon AND that same beam traveled 0 distance (Because 'space was contracted) in 0 time, umm or is it 186,282.40 miles traveled "Instantly"?and BOTH maths are considered "Simultaneous"?

Don't you think that this causes a "Duality" problem?

IF, there was a mirror at 186,282.40 miles, and if those photons were 'Really' getting there 'instantaneously', then would light travel time there and back only be 1/2 of what it should be ie; 1 second rather than the round trip time of 2 seconds?

So, to repeat my former question (and open with a question), how many other sources do I need to dig up? Paul Davies is a well-known and highly respected Physicist, not some crackpot I pulled off the wall. This is textbook Special Relativity. I can dig up more, but that's time-consuming, and I don't see how the conversation can go forward productively until you've read up on SR and can make your points in that context. But to answer your last question: No. The photons get there and back instantaneously--from their frame of reference. From yours, as the observer (a different frame of reference), they take time to get there and back. I can't seem to repeat often enough that the frames are different.

alainprice
2008-Oct-15, 07:15 PM
Textbook SR would be coming to the same conclusion as Einstein. The photon's frame of reference is not an inertial reference frame. You need to be careful when talking about 'the viewpoint of a photon'. The photon cannot experience time, so it does not have a view at all.

If I manage to get myself up to a speed whereby travelling to the moon and back leaves less than a planck unit of time elapsed on my watch, can I say I moved instantaneously? We won't measure any elapsed time.

thorkil2
2008-Oct-15, 09:21 PM
Textbook SR would be coming to the same conclusion as Einstein. The photon's frame of reference is not an inertial reference frame. You need to be careful when talking about 'the viewpoint of a photon'. The photon cannot experience time, so it does not have a view at all.

I thought I made clear that the use of "experience" was a loosely applied term. It's difficult to state because so many of the terms we might use imply consciousness, which is obviously not the case (though it is not required that the "laboratory" in the frame of reference under examination be real). But the idea is not contrary to any of Einstein's conclusions. The relationship between time and the photon relates entirely to speed. Time is dilated infinitely at c, unless you have an alternative interpretation to suggest.

If I manage to get myself up to a speed whereby travelling to the moon and back leaves less than a planck unit of time elapsed on my watch, can I say I moved instantaneously? We won't measure any elapsed time.

Hmm. Have to think about this. My gut reaction is that we are talking about apples and oranges. Planck time is the interval where quantum gravity should break the unity of space and time, and I'm talking about infinite time dilation at c. But I'll give your question some thought.
Bear in mind that I'm not talking about getting yourself up to any speed. I don't intend to suggest that it's possible to achieve c, but as I noted, the measuring laboratory can be an imaginary tool for addressing the question, and I'm only addressing to the relationship between time and a photon (or wave front) moving at c.

alainprice
2008-Oct-15, 09:47 PM
Even Einstein had to face the fact that the speed of light is not constant when exploring General relativity.

So even the speed of light isn't exactly constant. This may or may not cause you some problems.

Time stops alltogether to exist if all particles are massless, yet we can agree things happen in an order.

I believe the problem is out notion of time, of which I have yet to see a clear definition.

RussT
2008-Oct-16, 08:50 AM
Russ, what are you doing? You are writing as though you know nothing
at all about special relativity.

Jeff, Of Course I understand SR. KenG, Tensor, and Grey have all told me the same thing...ie; that I can't possibly understand IF I am not agreeing that they are correct when they/mainstream say that photons can travel from point A to point B at ANY distance in 0 time/"Instantaneously" AND that IF I just "Keep Googling"/studying, as KenG suggested, THEN I will have to come to the same conclusion...After all, we have 100+ years of peer review to back it up, right?

SO, I am just asking a series of questions designed to get 'someone' to actually 'think' (Re-think") about what has become 'rote answers' with blind acceptance...that photons can travel any "DISTANCE" to "Infinity" in 0 time.

And actually timb had a good point...

Because it is impossible for an observer to be in the frame of reference in question, you can at least be sure that your hypothesis will never be contradicted by experiment.

As did alainprice

The only way we can say a photon is instantaneous is if it has an instant effect, which has not been found.

The real question is....is it "Real"

SO, all I am really doing is asking tough questions...;)

thorkil2
2008-Oct-16, 05:07 PM
Jeff, Of Course I understand SR. KenG, Tensor, and Grey have all told me the same thing...ie; that I can't possibly understand IF I am not agreeing that they are correct when they/mainstream say that photons can travel from point A to point B at ANY distance in 0 time/"Instantaneously" AND that IF I just "Keep Googling"/studying, as KenG suggested, THEN I will have to come to the same conclusion...After all, we have 100+ years of peer review to back it up, right?

I respectfully submit that you do not understand SR. Your own words disqualify you:

First of all, THIS is absolutely False!
To make a flat out statement like this is absolutely irresponsible!
"c" can be Constant and Time can be Constant as well as 'Space'.

It is fundamental to SR that both space and time are frame dependent. Only if c were variable could space and time be constant. Not since Michelson-Morley.

SO, I am just asking a series of questions designed to get 'someone' to actually 'think' (Re-think") about what has become 'rote answers' with blind acceptance...that photons can travel any "DISTANCE" to "Infinity" in 0 time.

"Blind acceptance"?! These are not "rote answers." They are based on a well-supported understanding of the relationships between space, time, and motion under the special circumstances of SR. The math is solid. When you understand it, the logic is inescapable. It isn't something that needs rethinking.

At the speed of light, time dilation is infinite, which makes distance 0 by any measurement taken within a frame of reference moving at that speed. But it isn't something that affects you in any way in any frame of reference you have access to, so your measurement experiments are irrelevent. (edit) I will say again here, to fend off the inevitable nit-picking response from whomever, that it is perfectly permissible for the laboratory to be imaginary, so no, I don't have to justify putting a human instrumentality into motion at c. (end edit)

SO, all I am really doing is asking tough questions...;)

These are not "tough" questions at all, just irrelevent ones. You persist in arguing with examples that involve rest frame measurements having nothing to do with the frame of reference in question. You need to understand it before you can argue against it, and your own arguments negate your claim to understanding. There is an excellent history and exposition of the concepts of both SR and GR in Kip Thorne's Black Holes and Time Warps: Einstein's Outrageous Legacy. I recommend it highly. (Googling is great, but I still prefer pages with covers). :)

astromark
2008-Oct-16, 06:30 PM
Only a conscious sentient being has awareness. The photon light stream does not know time. If it did from its reference point it would see no time at all. From the reference point of any observer the photon stream takes time to transverse the distance, being C. The velocity of light. Not a lot of time for the short Earth moon distance, but still measurable.
What are you asking...? Is there a end goal here ?

Jeff Root
2008-Oct-16, 07:21 PM
Russ, what are you doing? You are writing as though you know nothing
at all about special relativity.
Jeff, Of Course I understand SR.
You know something about SR, but the evidence is that you don't
understand it. You dislike SR because it seems illogical to you.
That's a sure sign that you don't understand it.

KenG, Tensor, and Grey have all told me the same thing...ie; that
I can't possibly understand IF I am not agreeing that they are
correct when they/mainstream say that photons can travel from point
A to point B at ANY distance in 0 time/"Instantaneously" ...
That doesn't make grammatical sense, which is another clue that you
don't understand what they are saying. The words "at ANY distance"
do not fit grammatically into the rest of the clause.

Here are two correct ways of saying what you meant:

Photons travel from point A to Point B instantaneously in their own
proper time.

Photons do not experience proper time.

Photons are a bit like a person under general anesthesia, which I
experienced when my appendix was removed. One moment I'm on the
operating table, counting backwards "99, 98, 97..." and the next
I'm waking up in bed in the middle of the night. My brain was
turned off so I had no sense that several hours actually passed.

AND that IF I just "Keep Googling"/studying, as KenG suggested,
THEN I will have to come to the same conclusion...After all, we
have 100+ years of peer review to back it up, right?
There is no room for doubt that SR and GR accurately describe
what is observed. They do. And so far nobody has come up with
anything that describes what is observed any more accurately than
SR and GR.

If you are as intelligent as you seem to be, you should be able to
find a good explanation of SR and/or GR, study it carefully, and
understand it.

SO, I am just asking a series of questions designed to get 'someone'
to actually 'think' (Re-think") about what has become 'rote answers'
with blind acceptance...that photons can travel any "DISTANCE" to
"Infinity" in 0 time.
If you think that there is some logical error in SR or GR, then you
have made the error. The idea that measurements vary with different
relative speeds between the observer and the observed makes sense
to me. It is a very strange idea, beyond everyday experience, but
I have read explanations of it, and they make sense. They match
careful observation.

And actually timb had a good point...

As did alainprice

The real question is....is it "Real"

SO, all I am really doing is asking tough questions...;)
Differences in measurements due to differences in speed are as real
as differences in the angle to a mountaintop between an observer
five miles away and an observer ten miles away. They are entirely
and unreservedly real.

-- Jeff, in Minneapolis

thorkil2
2008-Oct-16, 07:23 PM
Only a conscious sentient being has awareness. The photon light stream does not know time. If it did from its reference point it would see no time at all. From the reference point of any observer the photon stream takes time to transverse the distance, being C. The velocity of light. Not a lot of time for the short Earth moon distance, but still measurable.
What are you asking...? Is there a end goal here ?

I've already addressed the consciousness issue, more than once, I believe. (edit) I see that you are agreeing with me in essence, but the issue of the question is addressed in my opening comments in this thread. (end edit)

pzkpfw
2008-Oct-16, 07:40 PM
(thorkil2, I think astromark agrees with you, and was adressing RussT).

Anyway, I was reading this and wanted to ask something, in a "devils advocate" kind of way. I'm not proposing it, I just think the answers might provide some more illumination.

Recently on BAUT there's been discussion that basically amounts to the idea that there isn't "really" a singularity at the centre of a black hole, it's just that the maths "runs out" at that point. Kind of (my words) "closer to centre, maths OK... closer to centre, maths OK... closer to centre, maths OK... closer, whoa, the maths went nuts, now we need a Quantum theory of Gravity, but for now let's assume there's a singularity".

Is there any chance at all that a similar kind of thing occurs in the "as things get faster" situation? As in, that at some point as we approach c the "maths breaks down" and some new idea (or maths or theory or something) comes into play?

(I'm happy to be told there is no answer, because my question simply makes no sense.)

Cougar
2008-Oct-16, 11:19 PM
Is there any chance at all that a similar kind of thing occurs in the "as things get faster" situation?

Well, in both cases, I see it as analogous to "1/n as n approaches 0." You can get as close as you want, but if you ever get there, the expression becomes undefined.

thorkil2
2008-Oct-17, 07:06 AM
(thorkil2, I think astromark agrees with you, and was adressing RussT).

Yes, I noticed that almost immediately and added the edit for that reason. First thing I saw was the remark about consciousness, which clouded the rest of my initial reading.

Anyway, I was reading this and wanted to ask something, in a "devils advocate" kind of way. I'm not proposing it, I just think the answers might provide some more illumination.

Recently on BAUT there's been discussion that basically amounts to the idea that there isn't "really" a singularity at the centre of a black hole, it's just that the maths "runs out" at that point. Kind of (my words) "closer to centre, maths OK... closer to centre, maths OK... closer to centre, maths OK... closer, whoa, the maths went nuts, now we need a Quantum theory of Gravity, but for now let's assume there's a singularity".

Is there any chance at all that a similar kind of thing occurs in the "as things get faster" situation? As in, that at some point as we approach c the "maths breaks down" and some new idea (or maths or theory or something) comes into play?

(I'm happy to be told there is no answer, because my question simply makes no sense.)

I'm not sure I'm not too tired to address this coherently, but here goes... First to address the "math running out" in the black hole. There is a substantial amount of matter that collapses to form a black hole. I don't think math failure is sufficient to account for what happens to it. It can't be accounted for as just a ball of "stuff" or "something" at the center of a gravity well because neither matter nor energy could support itself in any form under gravity intense enough to form a black hole in the first place. It isn't simply a matter of nothing being able to escape the event horizon. I believe every description of a black hole I've ever read addresses the impossibility of escape in terms of the event horizon as a boundary, but the event horizon is the outermost limit, that boundary beyond which (toward space) the escape velocity drops below c. In reality, it is the singularity itself from which nothing can escape, which suggests that it has a very definite reality. Nothing would be able to exist at all "between" (if such a word has any meaning at all in this context) the singularity and the event horizon except on a trajectory toward the singularity. But something went in. What consititutes annihilation in a singularity is difficult to fathom, but I don't think it's adequate to simply write off the singularity as a breakdown of the math.

Anything we say about motion at the speed of light involves abstractions, and while a breakdown of the math is possible, I doubt that's a good answer. Time dilation is an effect of motion only. Relative motion has consequences for mass and length, but they are corrollary with time dilation only to speed. Where all sub-c motion is relative, motion at c is absolute--the only characteristic which distinguishes it, but that breakdown of relativity of motion results from the fact that c is a limit at which t becomes infinite. As v approaches c, a certain pattern of change in time is established, toward greater and greater dilation, and well-supported by experimental evidence. It would be one thing if we were forced to stop with the asymptotic relationship between interval and v/c, but because we have a real world example of motion at c, we are justified in extending the pattern of time dilation to its logical and mathematical limits. If that makes any sense.... can hardly keep my eyes open at the moment.

RussT
2008-Oct-18, 06:25 AM
That doesn't make grammatical sense, which is another clue that you
don't understand what they are saying. The words "at ANY distance"
do not fit grammatically into the rest of the clause.

Here are two correct ways of saying what you meant:

Photons travel from point A to Point B instantaneously in their own
proper time.

Photons do not experience proper time.[

Fine Jeff...let's go with this one...Photons travel from point A to Point B instantaneously in their own proper time

So, are you telling me that IF I don't agree that this "Magic" is possible (Can "Really" Physically Happen), (and you do realize that Point B does actually mean to "Infinity" right? as if that is even that important), that I don't understand what SR is portraying???

Photons are a bit like a person under general anesthesia, which I
experienced when my appendix was removed. One moment I'm on the
operating table, counting backwards "99, 98, 97..." and the next
I'm waking up in bed in the middle of the night. My brain was
turned off so I had no sense that several hours actually passed.

Sorry, but this anology is meaningless.

There is no room for doubt that SR and GR accurately describe
what is observed.

Again, sorry, BUT there is plenty of room for doubt!!!

And again, If photons Cannot travel "Instananeously" to "The far ends of the universe" or "Instantaneously" to the Moon OR "instantaneously" at all anywhere, THEN 'time dilation' is pure meaningless mathematics.

You do realize that Einstein was working with an 'empty universe' when he developed SR, right?

But, let me make this easier for you...

Is there any 'scientific' way to detect any photons from Andromeda, that can 'detect' where Andromeda is "NOW" and IF it is even still where it 'should be'?

RussT
2008-Oct-18, 06:52 AM
At the speed of light, time dilation is infinite, which makes distance 0 by any measurement taken within a frame of reference moving at that speed. But it isn't something that affects you in any way in any frame of reference you have access to, so your measurement experiments are irrelevent. (edit) I will say again here, to fend off the inevitable nit-picking response from whomever, that it is perfectly permissible for the laboratory to be imaginary, so no, I don't have to justify putting a human instrumentality into motion at c. (end edit)

Yes, this paragraph above is what I mean with,..."Blind acceptance"?!

and the Bold means "Unfalsifiable"!

BUT, let me ask you this.

How do you determine which of these 3 things is 'really occuring'?

1. Is the "Space" contracting from Point A to Point B to make 0 distance? OR
2. Are the Photons traveling the distance from Point A to Point B "Instantaneously"? OR
3. Is "Time Dilating to Infinity" at the wave front as it is traveling?

Irrelevent questions.....right...

thorkil2
2008-Oct-18, 08:38 AM
Yes to all three questions. It's all the same thing. As you approach c, time is dilated, so the distance measured from the moving frame of reference becomes shorter and shorter as speed increases, because of time dilation. Time dilation and length contraction are speed dependent only. The photons travel from Point A to Point B with no elapsed time in their own frame, because Time is infinitely dilated at c, hence for anything (i.e., the wavefront) traveling at c.

To your Andromeda question, no, there is no photon arriving here and now that will depict the "now" location of Andromeda (if that even has any meaning). But again, I say the question is irrelevent. I've never said that you can observe instantaneous travel. You are not in a frame of reference in which time is stretched infinitely. You will measure photons traveling at a finite speed c. SR simply says that at c, no time passes for the photon. That doesn't mean the light got here from its source instantaneously from your vantage point. It isn't magic, it's geometry. And the bold you added doesn't mean "unfalsifiable." I said irrelevent because you continue to insist on mixing frames of reference. Experimental measurement of elapsed time for the movement of photons over a distance is something you do from your frame of reference only, and that will give you a finite value for d/t.

SagoSans
2008-Oct-18, 09:38 AM
How do you determine which of these 3 things is 'really occuring'?

1. Is the "Space" contracting from Point A to Point B to make 0 distance? OR
2. Are the Photons traveling the distance from Point A to Point B "Instantaneously"? OR
3. Is "Time Dilating to Infinity" at the wave front as it is traveling?

I'm not sure what you mean with 'really occuring':

A) according to Einstein's SRT, but you aren't sure what his theory is saying:
=> thorkil2 gave the answer

B) despite Einstein's SRT, because his theory is wrong:
=> I know far less than Einstein did, so I've got no better idea

Jeff Root
2008-Oct-18, 05:48 PM
That doesn't make grammatical sense, which is another clue that you
don't understand what they are saying. The words "at ANY distance"
do not fit grammatically into the rest of the clause.

Here are two correct ways of saying what you meant:

Photons travel from point A to Point B instantaneously in their own
proper time.

Photons do not experience proper time.
Fine Jeff...let's go with this one...Photons travel from point A to Point B
instantaneously in their own proper time

So, are you telling me that IF I don't agree that this "Magic" is possible
(Can "Really" Physically Happen), (and you do realize that Point B does
actually mean to "Infinity" right? as if that is even that important), that
I don't understand what SR is portraying???
Since I can't get into your head and know for sure what you mean by
the question, I am reluctant to answer "yes" or "no", but I will go ahead
and answer "yes". The fact that photons travel from place to place
instantaneously in their own proper time is a straightforward result of
applying the Lorentz transforms. If you don't see that, it must be
because you don't understand it.

Photons are a bit like a person under general anesthesia, which I
experienced when my appendix was removed. One moment I'm on the
operating table, counting backwards "99, 98, 97..." and the next
I'm waking up in bed in the middle of the night. My brain was
turned off so I had no sense that several hours actually passed.
Sorry, but this anology is meaningless.
You understood that it is an analogy. That's a good start.

It seems very simple and obvious to me. It was not meant to convey
anything complex or difficult. It should be a no-brainer. :)

There is no room for doubt that SR and GR accurately describe what
is observed.
Again, sorry, BUT there is plenty of room for doubt!!!
Where? Cite any reliable observation which conflicts with a prediction
of SR or GR.

And again, If photons Cannot travel "Instananeously" to "The far ends
of the universe" or "Instantaneously" to the Moon OR "instantaneously"
at all anywhere, THEN 'time dilation' is pure meaningless mathematics.
The fact that photons travel from one place to another instantaneously
in their own proper time is a result of applying the Lorentz transforms to
anything moving at the speed c. Muons created in collisions of cosmic
ray particles with Earth's upper atmosphere have measureable time
dilation that is less than infinite, in perfect accord with the prediction
of SR. Particle accelerators have to be designed to take time dilation
into account in their operation. As particles are accelerated to higher
and higher speeds, the time dilation increases exactly as predicted by
SR, and the functioning of the accelerators shows that. If the time
dilation were anything other than what is predicted by SR, or if it did
not occur at all, it would be very obvious in the accelerator output.

You do realize that Einstein was working with an 'empty universe' when
he developed SR, right?
I can only guess what you mean by "empty universe". Do you mean
that SR ignores gravity? If so, then yes, I realize that.

But, let me make this easier for you...

Is there any 'scientific' way to detect any photons from Andromeda,
that can 'detect' where Andromeda is "NOW" and IF it is even still
where it 'should be'?
I don't know what you mean by "where it 'should be'".

The Andromeda Galaxy is seen by the light of photons which left that
galaxy over two million years ago, our time. So we see the light coming
from the direction in which the galaxy was located over two million years
ago (with some slight adjustment for aberration of starlight).

-- Jeff, in Minneapolis

thorkil2
2008-Oct-19, 04:52 AM
Sorry, I set this aside to answer the other night, but was too tired to trust that I could answer coherntly, then forgot about it.

Even Einstein had to face the fact that the speed of light is not constant when exploring General relativity.

So even the speed of light isn't exactly constant. This may or may not cause you some problems.

Well, I confess, this is a new one on me. We are talking about the speed of light in a vacuum, of course, but under what circumstances is it not constant?

Time stops alltogether to exist if all particles are massless, yet we can agree things happen in an order.

Have to question this as well. I assume you are referring to GR and the relationship between the values of t at various distances from a gravitating body. But while if every particle were massless, there would be no warped geodesics, I don't see that as eliminating time, since it is not a consequence of mass and warped geodesics (only variations in the value for t with distance). Motion is affected by mass, as is relative interval, but the absense of mass would not negate the possibility of motion or time either one (though a Universe consisting entirely of massless particles probably would not long exist).

Time stops for massless particles traveling at c, and possibly if all motion were to stop, which would put an end to sequential events (but I pose that only as conjecture). Hard to get wrapped around that idea because even thinking an imaginary laboratory into that sitution inserts some kind of motion via consciousness. So long as things happen in order, there is time. If there is sequence, it must happen over an interval. We deal with relative motion, but what really happens if we extend the equations the other direction, to where all motion reaches absolute zero? Time is infinitely dilated at v/c = 1. On the other hand, t_0/t = 1 is only possible if v = 0_absolute. So what happens on that other end of the spectrum?

I believe the problem is out notion of time, of which I have yet to see a clear definition.

Interesting that something we know so well and use so extensively in mathematical descriptions of our world should lack a proper definition. I am satisfied with t as interval, which makes it more akin to length than mass. I think a definition would be more easily at hand if we got rid of the idea of time flowing and began to take it seriously as part of the geometry (i.e., the structural framework) of the Universe.

mugaliens
2008-Oct-19, 09:06 AM
Since you included your earlier content as quotes, I can't use the Quote function.

So we'll do it the hard way:

Thor...: "Quote:
Originally Posted by thorkil2
I don't see it as strange. For the photon or the wave front, the speed of light is infinite (edit) within that frame of reference (end edit). Zero distance from point a to point b (because it takes zero time to get there). Not hard then to see the Universe as a singularity from that frame of reference.

It's true that spacetime condenses to a singularity from the perspective of a frame where v --> c. That does not mean, however, that distance=0. All it means is that the perceived passage of time to transit that distance --> 0.

One can still get thwacked anywhere along that distance and never reach your destination. If distance truly --> 0, then the thwacking opportunity would also --> 0. It doesn't, so it ain't so.

Originally Posted by RussT
Ahhhhh, So, when 'science'/we/they/mainstream does the Lunar Ranging experiments, the photon/wave front is traveling 'instantly' to and from the moon??? Either? Neither?

Quote:
Originally Posted by thorkil2
So far as the observer is concerned, no. We measure a finite time of travel. But the photon, in it's own frame of reference, takes zero time to get from any point a to any point b anywhere in the Universe. It is only seen as finite speed from a frame of reference that is not moving at c.

As I understand it, from the photon's frame of reference, only the collection of paths along with it travels shrinks to a singularity. The remainder of the universe expands "to infinity, and beyond." Thus, all of existence becomes polarized to the road travelled, and the road not travelled.

Originally Posted by thorkil2
To put this another way, for c to be constant, time and space must be variable in the ways noted above.

Is it time and space which actually change in response to the oberserver's velocity?

No.

It's the observer's velocity vector which distorts their perception of time and space.

Originally Posted by thorkil2
Change frames, and you get different results. I'll say it differently: if I could use the word "experiences" loosely in this context, for lack of a better word, I would say the photon "experiences" no elapsed time from source to destination. That has nothing to do with what you measure because you are doing the measuring from a different frame of reference. It isn't instantaneous from any frame of reference you have access to, so no, there won't be instant effect. To the photon, however, the effect is instantaneous. Different frames of reference.

I would argue the results remain the same, although the perspective is different. I agree that to the photon, all excursions are instantaneous.

Originally Posted by RussT
Don't you think that this causes a "Duality" problem?

IF, there was a mirror at 186,282.40 miles, and if those photons were 'Really' getting there 'instantaneously', then would light travel time there and back only be 1/2 of what it should be ie; 1 second rather than the round trip time of 2 seconds?

Somewhere there's a serious disconnect between what Thor is saying and what you're hearing. I submit his original wording was a bit off kilter, and that while he's since stated it correctly since, you and others are clinging to the off-kilter comments.

I understand what he's saying, and see no contradiction with SR, now that he's stated things more clearly.

This is textbook Special Relativity.

I agree. It's textbook SR. From both of you. Now if you two can back off and figure out why when one says "orange" the other hears "fruit," I think your communication skills will have made a nice step forward.

thorkil2
2008-Oct-19, 09:20 AM
Since you included your earlier content as quotes, I can't use the Quote function.

So we'll do it the hard way:

It's true that spacetime condenses to a singularity from the perspective of a frame where v --> c. That does not mean, however, that distance=0. All it means is that the perceived passage of time to transit that distance --> 0.

One can still get thwacked anywhere along that distance and never reach your destination. If distance truly --> 0, then the thwacking opportunity would also --> 0. It doesn't, so it ain't so.

Let me suggest that you read my penultimate post prior to this answer (2 back, just before Sagosans). I disagree with your comment about distance, because you're also mixing frames. From the frame of reference of the same photon for which no time elapses, there is no distance because there is no elapsed time for the trip. From external frames, there is distance. The instantaneity of the trip for you (in an imaginary trip at c) doesn't preclude you from getting thwacked along the way, because anyone from outside your frame wanting to thwack you (and with good timing and aim) would have plenty of time to do so. As the saying goes, "you'll never know what hit you." I think that answers most of the rest of the post as well. It's important to keep the frames straight, and that's what RussT wasn't doing.

(EDIT) I should answer this one too.

Is it time and space which actually change in response to the oberserver's velocity?

No.

It's the observer's velocity vector which distorts their perception of time and space.

That isn't quite what happens. There is no distortion of the traveler's (which is what I assume you mean by observer in this case) perception of time. The clock ticks away exactly the same seconds within any frame of reference. Since you can only measure distance as vt, then because your clock ticks away fewer seconds than a rest frame clock, your measure of distance will be shorter than any measure taken from a relative rest frame. There is no distortion of perception, though I agree in essence with your comments about differences in routing through space-time. (end edit)

RussT
2008-Oct-19, 09:39 AM
I would argue the results remain the same, although the perspective is different. I agree that to the photon, all excursions are instantaneous

Well, this is Q&A, so I have been very careful to only ask questions...It might appear that I should be done...but I am NOT.

Let me just ask this...

Einstein was working with an 'empty universe' when he developed SR.
Distances meant nothing, even though he had the 'd' in the equations, they were really 0.

How does everyone that 'believes' (Yes, I used that word, because what you really think is that because 'time dilation' works mathematically, and, the logic is 'infallible', that this all must be 'true', even though you won't use that word) SR is correct, when it is dropped into GR, and there are 'real distances'...

Reconcile that light traveling to say Alpha Centauri 4 light years away, gets there in the same time that light would get to a star say...100 BILLION LIGHT YEARS AWAY...0 Time???

mugaliens
2008-Oct-19, 09:41 AM
The instantaneity of the trip for you (in an imaginary trip at c) doesn't preclude you from getting thwacked along the way, because anyone from outside your frame wanting to thwack you (and with good timing and aim) would have plenty of time to do so.

So external thwacks don't count? Tell that to the photon that just got thwacked by smacking itself into my frying pan at 299,792,458 m/s!

My point is that while photons perceive their origen and destination as a singularity, in reality they're two different points, separated by a distance.

Some like to claim that the photon's reality is that it's a singularity.

I differ, hence the line in my signature block about how they can be quite different.

thorkil2
2008-Oct-19, 09:54 AM
Well, this is Q&A, so I have been very careful to only ask questions...It might appear that I should be done...but I am NOT.

Let me just ask this...

Einstein was working with an 'empty universe' when he developed SR.
Distances meant nothing, even though he had the 'd' in the equations, they were really 0.

How does everyone that 'believes' (Yes, I used that word, because what you really think is that because 'time dilation' works mathematically, and, the logic is 'infallible', that this all must be 'true', even though you won't use that word) SR is correct, when it is dropped into GR, and there are 'real distances'...

This is not correct. Einstein developed SR for an idealized Universe which lacked gravity, not distance.

thorkil2
2008-Oct-19, 10:00 AM
So external thwacks don't count? Tell that to the photon that just got thwacked by smacking itself into my frying pan at 299,792,458 m/s!

My point is that while photons perceive their origen and destination as a singularity, in reality they're two different points, separated by a distance.

Some like to claim that the photon's reality is that it's a singularity.

I differ, hence the line in my signature block about how they can be quite different.

I'm not suggesting that it doesn't count. You insert your frying pan into the path in finite time, from your frame of reference and the photon gets thwacked. Whether the photon hits it, or doesn't hit it is no difference to the imaginary consciousness we've inserted to travel with it. The time is experienced as 0 regardless of the distance. It isn't a matter of perception. You can only measure distance by elapsed time times your known velocity. It's easier to see at speeds less than c, which is why the last few lines of the post I referenced may make it clearer.

RussT
2008-Oct-19, 10:35 AM
This is not correct. Einstein developed SR for an idealized Universe which lacked gravity, not distance.

This is shear Avoidance/deflection...I knew I shouldn't have prefaced the question with anything:(

How does anyone...

Reconcile that light traveling to say Alpha Centauri 4 light years away, gets there in the same time that light would get to a star say...100 BILLION LIGHT YEARS AWAY...0 Time???

Tinaa
2008-Oct-19, 02:55 PM
RussT stop trying to slip in your ATM ideas with a loaded question.

thorkil2
2008-Oct-19, 04:58 PM
This is shear Avoidance/deflection...I knew I shouldn't have prefaced the question with anything:(

Avoidance/deflection how? You made a statement which is historically and factually incorrect, and you seem to be basing conclusions on it. The only deflection I see is in your own own response quoted here.

How does anyone...

Reconcile that light traveling to say Alpha Centauri 4 light years away, gets there in the same time that light would get to a star say...100 BILLION LIGHT YEARS AWAY...0 Time???

At this point, I don't think it matters, but one more try... If you will read and try to comprehend the step-by-step description in the third paragraph of post #15, you may see "how does anyone..."

Jeff Root
2008-Oct-19, 05:45 PM
Russ,

The avoidance is entirely by you. If you dislike relativity so much that you
are compelled to believe it says things it doesn't say, no amount of correct
information about relativity will improve your understanding.

-- Jeff, in Minneapolis