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Mick
science forum beginner
Joined: 19 Jul 2005
Posts: 9
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 Posted: Thu May 18, 2006 7:29 pm Post subject:
How can time be relative?
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Please forgive me if I'm bringing up old subjects, I'm a newbie
here.
How can time be relative? Isn't the notion of time just a constant
that we create so that we can predict things, and determine the speed
at which things happen? To say that the speed is constant, and it is
the time that changes, seems like a trick of math that breaks the basic
ground rules.
Experiments have proven that a clock runs slower when it is taken on a
fast flight, than one which at rest. The conclusion is that time
passed more slowly for the speeding clock. How do we know that the
clock just doesn't operate slower when it is traveling fast? Maybe
atoms are less energetic when they are traveling faster, so therefore
the atomic clock runs slower?
Mike Lundberg
michael_s_lundberg@yahoo.com |
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Greg Neill
science forum Guru Wannabe
Joined: 31 May 2005
Posts: 180
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| Posted: Thu May 18, 2006 11:14 pm Post subject:
Re: How can time be relative?
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"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1147980565.343625.70430@i40g2000cwc.googlegroups.com...
| Quote: |
Experiments have proven that a clock runs slower when it is taken on a
fast flight, than one which at rest. The conclusion is that time
passed more slowly for the speeding clock. How do we know that the
clock just doesn't operate slower when it is traveling fast? Maybe
atoms are less energetic when they are traveling faster, so therefore
the atomic clock runs slower?
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How would you devise an experiment to tell the difference? |
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James Toupin
science forum addict
Joined: 06 Jul 2005
Posts: 57
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| Posted: Fri May 19, 2006 12:32 am Post subject:
Re: How can time be relative?
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"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1147980565.343625.70430@i40g2000cwc.googlegroups.com...
| Quote: | Please forgive me if I'm bringing up old subjects, I'm a newbie
here.
How can time be relative? Isn't the notion of time just a constant
that we create so that we can predict things, and determine the speed
at which things happen? To say that the speed is constant, and it is
the time that changes, seems like a trick of math that breaks the basic
ground rules.
|
Not at all. Time is a dimension just as real as the 3 physical dimensions of
length, width, and depth that we experience everyday. We move through the
temporal dimension (time) just as we move through the physical dimensions
with the only difference being that the temporal dimension can only be
travesed in one direction as far as we know at present.
Everything in the universe is moving though the four extended dimensions (3
spacial and 1 temporal dimension) at a constant combined velocity of c (the
speed of light). The higher the velocity through any one dimension leaves
less velocity to travel though the other dimensions. Hense; the faster
anything moves through "space" the slower it moves through time.
| Quote: | Experiments have proven that a clock runs slower when it is taken on a
fast flight, than one which at rest. The conclusion is that time
passed more slowly for the speeding clock. How do we know that the
clock just doesn't operate slower when it is traveling fast? Maybe
atoms are less energetic when they are traveling faster, so therefore
the atomic clock runs slower?
Mike Lundberg
michael_s_lundberg@yahoo.com
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Mick
science forum beginner
Joined: 19 Jul 2005
Posts: 9
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| Posted: Fri May 19, 2006 7:04 pm Post subject:
Re: How can time be relative?
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Greg Neill wrote:
| Quote: | "Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1147980565.343625.70430@i40g2000cwc.googlegroups.com...
Experiments have proven that a clock runs slower when it is taken on a
fast flight, than one which at rest. The conclusion is that time
passed more slowly for the speeding clock. How do we know that the
clock just doesn't operate slower when it is traveling fast? Maybe
atoms are less energetic when they are traveling faster, so therefore
the atomic clock runs slower?
How would you devise an experiment to tell the difference?
|
That's a good question. If Einstein was right, matter becomes more
massive as it approaches the speed of light. I'm not exactly sure
how an atomic clock works, but it seems reasonable that one would slow
down as it became more massive.
To my understanding, atomic clocks work by counting cycles of radiation
emitted as a transition between two energy levels of the ground state
of the Caesium-133 atom occurs. If the mass of an atom increases with
speed, then the energy within it must also increase, because mass and
energy are directly proportional according to Einstein. So, if this
means that the energy levels within the Caesium atom are higher
(further apart), then it seems to me that the emitted radiation would
be of a longer wavelength (slower) when energy levels are transitioned.
So, I think a clock should slow down as it increases in speed. To be a
really good clock, it would have to somehow compensate for that, and I
don't think they do. Maybe I'm totally misunderstanding the
principle of how an atomic clock works, so if I'm wrong, someone
please enlighten me.
Again, I think of time as just a (constant) reference that we invent to
make sense of the world. It's the only way to predict events and it
allows us to interact with moving objects. We create a constant time
reference from which we measure everything else. Time isn't
relative, speed is. ....But, that is a whole other issue....
Mike Lundberg
michael_s_lundberg@yahoo.com |
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Greg Neill
science forum Guru Wannabe
Joined: 31 May 2005
Posts: 180
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| Posted: Fri May 19, 2006 7:52 pm Post subject:
Re: How can time be relative?
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"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1148065494.050666.251190@g10g2000cwb.googlegroups.com...
| Quote: |
Greg Neill wrote:
"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1147980565.343625.70430@i40g2000cwc.googlegroups.com...
Experiments have proven that a clock runs slower when it is taken on a
fast flight, than one which at rest. The conclusion is that time
passed more slowly for the speeding clock. How do we know that the
clock just doesn't operate slower when it is traveling fast? Maybe
atoms are less energetic when they are traveling faster, so therefore
the atomic clock runs slower?
How would you devise an experiment to tell the difference?
That's a good question. If Einstein was right, matter becomes more
massive as it approaches the speed of light. I'm not exactly sure
how an atomic clock works, but it seems reasonable that one would slow
down as it became more massive.
|
The problem here is that the increase is mass is only
apparent to the observer *not* travelling at the speed
of light. In other words, in the clock's frame of
reference, everything it is composed of and everything
moving along with it seems perfectly unaffected. There
is no test that an observer moving with the clock could
perform to detect any change at all. |
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Mick
science forum beginner
Joined: 19 Jul 2005
Posts: 9
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| Posted: Sat May 20, 2006 4:32 pm Post subject:
Re: How can time be relative?
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Greg Neill wrote:
| Quote: | "Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1148065494.050666.251190@g10g2000cwb.googlegroups.com...
Greg Neill wrote:
"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1147980565.343625.70430@i40g2000cwc.googlegroups.com...
Experiments have proven that a clock runs slower when it is taken on a
fast flight, than one which at rest. The conclusion is that time
passed more slowly for the speeding clock. How do we know that the
clock just doesn't operate slower when it is traveling fast? Maybe
atoms are less energetic when they are traveling faster, so therefore
the atomic clock runs slower?
How would you devise an experiment to tell the difference?
That's a good question. If Einstein was right, matter becomes more
massive as it approaches the speed of light. I'm not exactly sure
how an atomic clock works, but it seems reasonable that one would slow
down as it became more massive.
The problem here is that the increase is mass is only
apparent to the observer *not* travelling at the speed
of light. In other words, in the clock's frame of
reference, everything it is composed of and everything
moving along with it seems perfectly unaffected. There
is no test that an observer moving with the clock could
perform to detect any change at all.
|
Huh? Is that right? I thought the whole reason that we (supposedly)
can't break the speed of light barrier was because objects become
infinitely massive and require infinite energy to be moved any faster. |
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Greg Neill
science forum Guru Wannabe
Joined: 31 May 2005
Posts: 180
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| Posted: Sat May 20, 2006 6:01 pm Post subject:
Re: How can time be relative?
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"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1148142776.800465.48960@u72g2000cwu.googlegroups.com...
| Quote: |
Greg Neill wrote:
"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1148065494.050666.251190@g10g2000cwb.googlegroups.com...
Greg Neill wrote:
"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1147980565.343625.70430@i40g2000cwc.googlegroups.com...
Experiments have proven that a clock runs slower when it is taken on a
fast flight, than one which at rest. The conclusion is that time
passed more slowly for the speeding clock. How do we know that the
clock just doesn't operate slower when it is traveling fast? Maybe
atoms are less energetic when they are traveling faster, so therefore
the atomic clock runs slower?
How would you devise an experiment to tell the difference?
That's a good question. If Einstein was right, matter becomes more
massive as it approaches the speed of light. I'm not exactly sure
how an atomic clock works, but it seems reasonable that one would slow
down as it became more massive.
The problem here is that the increase is mass is only
apparent to the observer *not* travelling at the speed
of light. In other words, in the clock's frame of
reference, everything it is composed of and everything
moving along with it seems perfectly unaffected. There
is no test that an observer moving with the clock could
perform to detect any change at all.
Huh? Is that right? I thought the whole reason that we (supposedly)
can't break the speed of light barrier was because objects become
infinitely massive and require infinite energy to be moved any faster.
|
Right, but it is an observer dependent phenomenon. Let's
say that there are two observers. One is riding with a
rocket while the other stays put at the launch site. The
rocket is designed in such a fashion that it will produce
exactly the right amount of force to produce a constant 1g
acceleration according to the on-board observer.
The stay-behind observer will see the rocket launch and move
away with an acceleration of 1g until its relative speed
becomes a significant fraction of the speed of light. At this
point it appears that the rocket is accelerating less and
less the closer it gets to the speed of light. Since the
rocket is presumably still operating according to its design
spec and producing the designed amount of force, it appears
to the stay-behind observer that the rocket must be increasing
in mass.
The observer on the rocket, on the other hand, keeps a record
of his acceleration using an on-board accelerometer and sees
that the acceleration remains at 1g at all times. Everything
appears perfectly normal within his ship.
Other effects come into play, too. The observer in the rocket
will see the distance to his destination shrinking just as
though his acceleration was a continuous 1g and there was no
speed of light barrier, yet if he measures the speed of approach
of his destination, he will never measure a value greater than
c. This is the length contraction effect of relativity. The
travelling observer will, by his clock, reach the destination
in a shorter time than the original distance and the speed of
light limit would have suggested. Meanwhile, the stay-behind
observer will not see a contracted distance and will see the
ship's acceleration decrease over the trip. The time taken
for the ship to reach its destination will be in accord with
his idea of the distance covered and the speed attained by the
rocket. In other words, the rate of time flow for the other
observer as seen by each of them will appear to be different
(In fact each observer will see the other's clock as running
slow). |
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Mick
science forum beginner
Joined: 19 Jul 2005
Posts: 9
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| Posted: Sun May 21, 2006 8:45 pm Post subject:
Re: How can time be relative?
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Greg Neill wrote:
| Quote: | "Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1148142776.800465.48960@u72g2000cwu.googlegroups.com...
Greg Neill wrote:
"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1148065494.050666.251190@g10g2000cwb.googlegroups.com...
Greg Neill wrote:
"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1147980565.343625.70430@i40g2000cwc.googlegroups.com...
Experiments have proven that a clock runs slower when it is taken on a
fast flight, than one which at rest. The conclusion is that time
passed more slowly for the speeding clock. How do we know that the
clock just doesn't operate slower when it is traveling fast? Maybe
atoms are less energetic when they are traveling faster, so therefore
the atomic clock runs slower?
How would you devise an experiment to tell the difference?
That's a good question. If Einstein was right, matter becomes more
massive as it approaches the speed of light. I'm not exactly sure
how an atomic clock works, but it seems reasonable that one would slow
down as it became more massive.
The problem here is that the increase is mass is only
apparent to the observer *not* travelling at the speed
of light. In other words, in the clock's frame of
reference, everything it is composed of and everything
moving along with it seems perfectly unaffected. There
is no test that an observer moving with the clock could
perform to detect any change at all.
Huh? Is that right? I thought the whole reason that we (supposedly)
can't break the speed of light barrier was because objects become
infinitely massive and require infinite energy to be moved any faster.
Right, but it is an observer dependent phenomenon. Let's
say that there are two observers. One is riding with a
rocket while the other stays put at the launch site. The
rocket is designed in such a fashion that it will produce
exactly the right amount of force to produce a constant 1g
acceleration according to the on-board observer.
The stay-behind observer will see the rocket launch and move
away with an acceleration of 1g until its relative speed
becomes a significant fraction of the speed of light. At this
point it appears that the rocket is accelerating less and
less the closer it gets to the speed of light. Since the
rocket is presumably still operating according to its design
spec and producing the designed amount of force, it appears
to the stay-behind observer that the rocket must be increasing
in mass.
The observer on the rocket, on the other hand, keeps a record
of his acceleration using an on-board accelerometer and sees
that the acceleration remains at 1g at all times. Everything
appears perfectly normal within his ship.
Other effects come into play, too. The observer in the rocket
will see the distance to his destination shrinking just as
though his acceleration was a continuous 1g and there was no
speed of light barrier, yet if he measures the speed of approach
of his destination, he will never measure a value greater than
c. This is the length contraction effect of relativity. The
travelling observer will, by his clock, reach the destination
in a shorter time than the original distance and the speed of
light limit would have suggested. Meanwhile, the stay-behind
observer will not see a contracted distance and will see the
ship's acceleration decrease over the trip. The time taken
for the ship to reach its destination will be in accord with
his idea of the distance covered and the speed attained by the
rocket. In other words, the rate of time flow for the other
observer as seen by each of them will appear to be different
(In fact each observer will see the other's clock as running
slow).
|
I'm not sure I understand what you mean by: "The observer in the
rocket will see the distance to his destination shrinking just as
though his acceleration was a continuous 1g and there was no speed of
light barrier, yet if he measures the speed of approach of his
destination, he will never measure a value greater than c."
The part I do not understand is, the different between measuring the
"speed of approach" vs "see(ing) the distance to his destination
shrinking ... ". Either way, I would think that he has to take
periodic measurements to his destination (or, I suppose to his origin),
and the periodicity of those reading would be based on his own clock.
If I am understanding paradox correctly, from the stay-behind
observer's point of view (clock), it took the rocket a lot longer to
reach it's destination than it seemed to take for the observer in the
rocket (based on his clock).
My point is; how do we know that? I don't pretend to be up on all
the experiments, and I assume it has been proven to the satisfaction of
the mainstream physics, but the only one I know about is where they
take two synchronized clocks, take one of them for a ride, then compare
them later, and find that the one which traveled is showing an earlier
time. Again, I ask, how can we be certain that the clock didn't just
run slower for some physical reason, which has to do with traveling
fast? The observer in the ship wouldn't know that his clock is
running slower, it what he measures everything else with. I don't
know why a clock would run slower when it is traveling faster, but it
seems easier to accept than to say that time itself is different for
the two observers. |
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Greg Neill
science forum Guru Wannabe
Joined: 31 May 2005
Posts: 180
|
| Posted: Sun May 21, 2006 10:14 pm Post subject:
Re: How can time be relative?
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"Mick" <michael_s_lundberg@yahoo.com> wrote in message
news:1148244353.652198.142390@u72g2000cwu.googlegroups.com...
| Quote: |
I'm not sure I understand what you mean by: "The observer in the
rocket will see the distance to his destination shrinking just as
though his acceleration was a continuous 1g and there was no speed of
light barrier, yet if he measures the speed of approach of his
destination, he will never measure a value greater than c."
The part I do not understand is, the different between measuring the
"speed of approach" vs "see(ing) the distance to his destination
shrinking ... ". Either way, I would think that he has to take
periodic measurements to his destination (or, I suppose to his origin),
and the periodicity of those reading would be based on his own clock.
|
He measures the speed at which his destination is approaching
(which by symmetry is the apparent speed with which he is
travelling towards his destination), and it never exceeds c.
Similarly, the speed that he measures for his receeding from
his starting point never exceeds c.
| Quote: |
If I am understanding paradox correctly, from the stay-behind
observer's point of view (clock), it took the rocket a lot longer to
reach it's destination than it seemed to take for the observer in the
rocket (based on his clock).
|
Right.
| Quote: |
My point is; how do we know that? I don't pretend to be up on all
the experiments, and I assume it has been proven to the satisfaction of
the mainstream physics, but the only one I know about is where they
take two synchronized clocks, take one of them for a ride, then compare
them later, and find that the one which traveled is showing an earlier
time. Again, I ask, how can we be certain that the clock didn't just
run slower for some physical reason, which has to do with traveling
fast? The observer in the ship wouldn't know that his clock is
running slower, it what he measures everything else with. I don't
know why a clock would run slower when it is traveling faster, but it
seems easier to accept than to say that time itself is different for
the two observers.
|
The clocks used are based upon fundamental quantum motions
that are taking place in carefully controlled circumstances.
The clocks are not subject to any environmental vagaries,
and are moving (for the most part) in what are essentially
inertial frames of reference. Further, clocks of all types
suffer exactly the same effects despite being constructed
on differing physical principles (there's more than one type
of atomic clock, for instance).
But this is not the only experiment that shows the effects
of relativity on time. There are also particle decay rates
(such as muon decay from cosmic ray showers), for example.
The GPS system also displays the effects, and their clocks
need to be compensated for both the velocity effects of
special relativity, as well as the gravitational effect
on time rate of general relativity. |
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