Is there a deeper time?

Now I know that relativity tells us that going faster than light would
mean travelling backwards in time. And one of the examples they often
give is that looking at stars and galaxies means we're looking back in
time. Okay that's all pretty easy to understand, it took the light some
time to travel from the star or galaxy to our eyes (or instruments).
We're seeing an image that started travelling to us several years ago.
But to me that just means we're seeing an image from an earlier time,
how is that supposed to be time travel? As an example, we can hear a
thunderclap several seconds after we can see it. The sound took a
certain amount of time to travel to us; it's an image of a sound
produced earlier but just now getting to us. However, if I go supersonic
and try to catch up with the sound earlier, I don't consider myself to
have travelled backwards in time to hear the sound earlier.

Yet in relativity, going *at* the speed of light means time stops
entirely for you. Yet, in our normal world, we see events where photons
crash into objects all of the time, but from the photon's own
perspective, there is nothing that's happening? The photon experiences
no events because time has stopped for it? That's why I'm asking if
there is a "deeper" time at the heart of the universe, one which records
events happening even at the speed of light, when what we normally call
time stops?

Yousuf Khan

I'm fairly sure of this, but I wouldn't bet the farm, because then we'd
have no pecans to sell.

Yousuf Khan wrote:
Now I know that relativity tells us that going faster than light would
mean travelling backwards in time.

No--the premise in relativity is that the speed of light cannot
even be attained by particles with rest mass as is empirically
born out.

Yousuf Khan wrote:
Now I know that relativity tells us that going faster than light would
mean travelling backwards in time. And one of the examples they often
give is that looking at stars and galaxies means we're looking back in
time. Okay that's all pretty easy to understand, it took the light some
time to travel from the star or galaxy to our eyes (or instruments).
We're seeing an image that started travelling to us several years ago.
But to me that just means we're seeing an image from an earlier time,
how is that supposed to be time travel? As an example, we can hear a
thunderclap several seconds after we can see it. The sound took a
certain amount of time to travel to us; it's an image of a sound
produced earlier but just now getting to us. However, if I go supersonic
and try to catch up with the sound earlier, I don't consider myself to
have travelled backwards in time to hear the sound earlier.

Yet in relativity, going *at* the speed of light means time stops
entirely for you. Yet, in our normal world, we see events where photons
crash into objects all of the time, but from the photon's own
perspective, there is nothing that's happening? The photon experiences
no events because time has stopped for it? That's why I'm asking if
there is a "deeper" time at the heart of the universe, one which records
events happening even at the speed of light, when what we normally call
time stops?

Yousuf Khan

So IOW you want to know how special relativity plus FTL signaling equals
causality violation and backward time travel?

http://www.faqs.org/faqs/star-trek/r...ity_FTL/part4/

Richard Perry

Yousuf Khan wrote:
Now I know that relativity tells us that going faster than light would
mean travelling backwards in time.

Actually it doesn't. Relativity does not and cannot say anything about
travelling forward or backward in time. It doesn't distinguish the two
directions in any way.

One can make an argument that faster-than-light travel plus the principle of
relativity would imply time travel, but I think it's a weak argument. The
arrow of time is usually explained by saying that time symmetry is broken by
the big bang. The principle of relativity is also broken by the big bang,
and I see no reason why this same mechanism couldn't also prevent
communication into the past using tachyons.

And one of the examples they often
give is that looking at stars and galaxies means we're looking back in
time. [...]
But to me that just means we're seeing an image from an earlier time,
how is that supposed to be time travel?

You're right, they're wrong about there being a connection to time travel.

Yet in relativity, going *at* the speed of light means time stops
entirely for you. Yet, in our normal world, we see events where photons
crash into objects all of the time, but from the photon's own
perspective, there is nothing that's happening?

This is tricky. Basically, light can't change internally, because there's no
time scale on which the change can happen. For example, particles which
travel slower than light -- like muons and atoms -- can be unstable and
decay, but light can't. However, that doesn't prevent light from being
changed by an external influence, like a collision with something else.

-- Ben

Yousuf Khan wrote:

Now I know that relativity tells us that going faster than light would
mean travelling backwards in time.

Really, really bad start.

And one of the examples they often
give is that looking at stars and galaxies means we're looking back in
time.

Getting worse.

Okay that's all pretty easy to understand, it took the light some
time to travel from the star or galaxy to our eyes (or instruments).
We're seeing an image that started travelling to us several years ago.
But to me that just means we're seeing an image from an earlier time,
how is that supposed to be time travel? As an example, we can hear a
thunderclap several seconds after we can see it. The sound took a
certain amount of time to travel to us; it's an image of a sound
produced earlier but just now getting to us. However, if I go supersonic
and try to catch up with the sound earlier, I don't consider myself to
have travelled backwards in time to hear the sound earlier.

Every child left behind.

Yet in relativity, going *at* the speed of light means time stops
entirely for you.

Why don't you calcualte gamma for v=c?

Yet, in our normal world, we see events where photons
crash into objects all of the time, but from the photon's own
perspective, there is nothing that's happening?

Photon POV is not an inertial reference frame.

The photon experiences
no events because time has stopped for it? That's why I'm asking if
there is a "deeper" time at the heart of the universe, one which records
events happening even at the speed of light, when what we normally call
time stops?

Wouldn't you rather be in management?

http://www.dilbert.com/

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

Sam Wormley wrote:
Yousuf Khan wrote:

Now I know that relativity tells us that going faster than light would
mean travelling backwards in time.


No--the premise in relativity is that the speed of light cannot
even be attained by particles with rest mass as is empirically
born out.

That's not really an answer, is it? It's just a diversion of the
subject. Don't let this subject get hijacked by the newsgroup kooks
trying to push their own little pet theories, it's a serious question.

Explain why lightspeed travel is time stopped, and why FTL is backwards
time travel, never mind whether you think it's practical or not. Pretend
that I'm an intelligent photon, now why has time stopped for me, and why
are no events happening to me? And why is it that the rest of the
slower-than-me world sees me doing all kinds of things, like vibrating
and racing past them headed towards some object to smack into it and
maybe bounce off or get absorbed by it, when I, myself, am completely
unaware of all that?

Yousuf Khan

Yousuf Khan wrote:
Sam Wormley wrote:
Yousuf Khan wrote:

Now I know that relativity tells us that going faster than light would
mean travelling backwards in time.


No--the premise in relativity is that the speed of light cannot
even be attained by particles with rest mass as is empirically
born out.

That's not really an answer, is it? It's just a diversion of the
subject. Don't let this subject get hijacked by the newsgroup kooks
trying to push their own little pet theories, it's a serious question.

In relativity theory, a massive particle travelling slower than
lightspeed cannot accelerate past the lightspeed barrier since it would
require infinite energy. It is therefore impossible to start below
light speed and end up faster than light speed. This is what Sam was
referring to.

What Sam failed to realize was that this does not prevent a particle
from having been created with faster than light speed. Such theoretical
particles are called tachyons. In Quantum Field Theory, a tachyon could
explain the spontaneous violation of the electroweak symmetry, and
various other phenomenon. A fundamental problem for tachyons though is
that since they can posses negative energy they violate spacetime
supersymmetry (since energy must be the square of the supercharge,
roughyl speaking). One should note that spacetime supersymmetry is
empirically false. The existence of FTL particles is still something
unclear.



Explain why lightspeed travel is time stopped, and why FTL is backwards
time travel, never mind whether you think it's practical or not. Pretend
that I'm an intelligent photon, now why has time stopped for me, and why
are no events happening to me? And why is it that the rest of the
slower-than-me world sees me doing all kinds of things, like vibrating
and racing past them headed towards some object to smack into it and
maybe bounce off or get absorbed by it, when I, myself, am completely
unaware of all that?

Those questions can be answered by finding/reading wikipedia special
relativity articles.

Yousuf Khan

"Yousuf Khan" wrote in message
...

That's not really an answer, is it? It's just a diversion of the subject.
Don't let this subject get hijacked by the newsgroup kooks trying to push
their own little pet theories, it's a serious question.

If you are serious then there are resource that will
help and some people have already suggested places
you can start. The thing is that you can't just pick
up an understanding of relativity in a few usenet
posts, you need to study the subject. It took me a
few months to learn enough to understand why time
travel would be a consequence of FTL motion.

Explain why lightspeed travel is time stopped, and why FTL is backwards
time travel, never mind whether you think it's practical or not.

Time and space are ways of describing the 4D universe
we live in, but to an extent they are interchangeable
just as a vector can be split into x and y components
in more than one way. However, those components are
always related by Pythagoras Theorem to the length of
the vector. A similar relationship occurs between
space and time but the sign of the time component is
negated. The consequence is that the time it takes
to get anywhere as measured on a spaceship is less
than the time measured by someone left behind watching,
at as you approach the speed of light, the shipboard
time approaches zero.

If you could travel faster than light (as measured
here) to some distant planet which is moving away from
us, then return faster than light as measured from that
planet, you would arrive back here before you left.

The obvious conclusion is that, if you think getting
back before you left is impossible, then so is FTL
motion.

BTW, the shipboard time for each leg of the journey
would be imaginary!

Pretend that I'm an intelligent photon, now why has time stopped for me,
and why are no events happening to me? And why is it that the rest of the
slower-than-me world sees me doing all kinds of things, like vibrating and
racing past them headed towards some object to smack into it and maybe
bounce off or get absorbed by it, when I, myself, am completely unaware of
all that?

From your point of view, there is no distance or time
between your creation and destruction. You are unaware
of everything, even your own existence.

It doesn't really help much to try thinking that way.
Get a decent introductory textbook from the library.
The one I usually recommend is "Spacetime Physics"
by Taylor and Wheeler but you'll find other book
lists on many web sites:

http://www.amazon.com/exec/obidos/tg...544736-5476764

HTH
George

Yousuf Khan wrote:
Sam Wormley wrote:

Yousuf Khan wrote:

Now I know that relativity tells us that going faster than light
would mean travelling backwards in time.



No--the premise in relativity is that the speed of light cannot
even be attained by particles with rest mass as is empirically
born out.


That's not really an answer, is it? It's just a diversion of the
subject. Don't let this subject get hijacked by the newsgroup kooks
trying to push their own little pet theories, it's a serious question.

Explain why lightspeed travel is time stopped, and why FTL is backwards
time travel, never mind whether you think it's practical or not.

o since clock can't attain c, time is not stopped.

o since one cannot travel FTL, your question make no sense.

Are There Any Good Books on Relativity Theory?
http://math.ucr.edu/home/baez/physic..._booklist.html