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Old 06-03-2003, 05:51 PM   #1 (permalink)
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another time/relativity question

So in my layman's understanding (meaning conceptual, not mathematical) of the theory of general relativity it seems that Einstein is telling us that there is no truly objective vantage point from which to observe objects. For instance, if I was standing next to the highway and a car drove by, i would be able to clock its speed at a certain number, say 69 mph. This number would seem to corroborate what my senses tell me. Now, if someone in that car was able to bounce a signal from their radar gun off of me, it would also return a reading of 69 mph. Thus, this measurement does not truly tell me how fast the car is moving, it only tells me how fast the car is moving relative to me. This is further born out by my knowledge that the earth is not only rotating, but is also hurtling through space, so even though I fell as though I am not moving, I clearly am. To sum up, motion is relative to perspective and there is no meaningful way to objectively determine trajectory and velocity unless one first specifies a vantage point.

Secondly, I think that general relativity is telling me that the perceived rate of passage of time is dependent on velocity. Namely, local time passes slower for objects moving more quickly. So, for instance if I am sitting still and I measure a particle that is moving at 90% of the speed of light, time passes more slowly for that particle. Even better, if there was a clock ON the particle, it would register less elapsed time than my wristwatch would in any given period, as long as that particle keeps moving close to the speed of light.

Now (finally) my question is this... If motion is relative, how do these clocks know which one should slow down and which one should speed up? If it is the particle that is moving, my watch will register more elapsed time. If it is me that is moving, my wristwatch should register less elapsed time. Logic would seem to suggest that only one of these things could be true at a time, but my first paragraph would suggest there is not any difference between our motions save the vantage point of the observer. Now, I seem to recall reading once that this time dilation is a real and measurable phenomenon, not just a theoretical abstraction. So I have a contradiction here, and one of my favorite authors says that there are no contradictions in the natural world. When we are faced with one we should check our premises. Have I misunderstood one of these two points concerning relativity? Or is this somehow similar to the physics experiment of the two holes (in which light can behave as a particle or as a wave [meaning displaying phase interference or not] depending on which result the observer is looking for) and so the position of the observer somehow determines the outcome of the experiment? If you have a better understanding of the specific mathematics here, please help me out!
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Old 06-03-2003, 07:15 PM   #2 (permalink)
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It's your clock comparisons, between the one at a slower velocity and the faster velocity.
So this makes the speed of the Earth and the Galaxy irrelevant.

Either by the warping of gravity or by speed of an object,
time slows down.
Now since the gravity tends to be consistent, that will actually be slower
because it is the mass of the object warping the space-time dimensions.

But on the relativistic aspects of velocity, time doesn't TRUELY slow down,
it only seems to in comparison from your "static" clock to your "moving" clock.
If you took two clocks, and did a test in the same gravitational well level (all the way around),
moving one at super-sonic speeds around the Earth, and took three samples.
One at the start before moving, one in the middle while moving
and one at the end after moving in the exact same area as you started.
then you will note that the first & third same there is no difference.
But on the second sample it would seem the moving one was slower.
Thus relativity.
It's all perspective, dude.

Not reality, like the sci-fi people would like you to have it.
There is at time some confusion due to the limitations of language,
and someone is trying to make a point.

People will not age slower while going at the speed they do in space, not ever will...
unless they get caught in a serious gravity well, but then you have different issues.
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Old 06-04-2003, 10:10 AM   #3 (permalink)
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First off, your *perception* of time is totally unaltered by your speed. It is not your perception that is changing -- it is *time* that is changing. Most of us humans have a hard time accepting this, as we live in a low speed, low energy world. But experiment has proven time and again that relativatiy is a valid description of the universe. It predicts things for which we have no other explanation, and it does so very well.

How does a clock 'know' to change? The answer here is the speed of light. That is the speed limit. The first concept that is useful is that of 'proper time.' Any time measurement that is made in the reference frame of a particle is the longest measurement of time possible. But more importantly, you have banished relativity in you last paragraph, and that is you primary problem. There is no difference: you are moving, the particle is moving, *it simply does not matter in the least.* I can find another reference frame in which you are moving *and* the particle is moving. Your idea about what velocity is confused. To you, the particle is clicking of time slower. To the particle, you are clikcing off time to fast, to another observer, you would both be screwing it up. Bottom line: time is relative.

I suggest you check out a physics book on special relativaty, as I am not explaining it all that well, but there is no contradiction. This stuff has been subject to extreme scrutiny over the last 100 years. The math is not hard: you need to know algebra.

Did you know that GPS satelites would not work accurately with out relativity? Given their 24000 mph rel. velocity, and the bouncing signals, if you don't take relativity into account, over weeks you begin to get a drifts in the clocks on the satelines of a couple of seconds. Eventually, a plane crashes because the clocks are so badly out of sinc. For something as mundane as navigation, we need relativity. Go figure.
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Old 06-04-2003, 12:42 PM   #4 (permalink)
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I guess I dont have your depth of knowledge on this subject so please forgive my ignorance . . . but : -

- If I am in a car going at 60mph in one direction and a friend is going at 60mph in the opposite direction then we pass at 120mph.
This is similar to one of us standing still and the other going past at 120mph . . or even one of us going backwards at 60mph and the other going past at 180mph . . .the relative difference is always 120mph because I disregard our 'actual' speeds relative to the ground and consider only our relative speeds.

So far so good . . now the bit where I get stuck . . if whilst travelling in one direction at 60mph I shine a torch forwards . . the light moves away from me at the speed of light REGARDLESS of my travelling speed . . the torch does not know I am moving.

My friend, travelling at 60 mph in the opposite direction, also shines a torch . . . now his light presumably also moves away from him at the speed of light? So the photons from my torch and the photons from his torch are moving away from each other at TWICE the speed of light PLUS 120mph . . . . . . . . . now I feel this is wrong becuase I believe the speed of light cannot be exceeded (is that right?) so whats going on there?
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Old 06-04-2003, 01:56 PM   #5 (permalink)
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I read a book a few years ago called 'Reletivity Visualized'

http://www.amazon.com/exec/obidos/tg/detail/-/093521805X/qid=1054763330/sr=1-1/ref=sr_1_1/102-6295499-4897711?v=glance&s=books

It was written for laymen and provided nice analogies and models for these concepts. In reguard to time dialation I believe that the model provided was this:
You always travel through spacetime at the speed of light. when you are at rest in 3-space you are traveling through time at the speed of light. when you move through 3-space the speed you are moving at is subtracted from the speed you are traveling through time at. You notice nothing either way even if you are traveling through 3-space at a large % of light speed. People moving relative to you notice this.
This may be incorect. I would recomend the book for a more accurate description.
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Old 06-04-2003, 02:49 PM   #6 (permalink)
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duckznutz,
The flashlight thing is explained by light frequency shift. If I am moving quickly towards a red light it will shift up the frequency to green, blue and eventually out of the visible spectrum. If I am moving away from a light source at a high velocity it will shift down in frequency. If you are a trekkie you can see the effect out the windows when the ships are travelling at warp. Stars are stretched out over the full visible spectrum of light from red to blue, very cool.
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Old 06-04-2003, 02:56 PM   #7 (permalink)
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Re: another time/relativity question

Quote:
Originally posted by ubertuber
If it is the particle that is moving, my watch will register more elapsed time. If it is me that is moving, my wristwatch should register less elapsed time.
Uber, you answered your own question. If you are watching the particle it's time interval is slower than yours, seconds tick by slower on it's clock. If the particle is watching you, it thinks it is standing still and it thinks you are moving past it at very high velocity and your watch is running slowly. It's all about who is observing whom.

Hope this helps.
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Old 06-04-2003, 05:44 PM   #8 (permalink)
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teece it is perspective, in terms of what I described. (a velocity test)

The time is NOT changing in the GPS satellite because of velocity, but dimensional warp.
Each has to do with two different sections of the Theory of Relativity.

But the time comparisons between the two are:
1) Because of the speed it is moving away or towards the relatively stationary Earth position,
but for the most part it's a geostationary orbit. (this is minimal, if at all.)
2) Most important, the gravitational well is MUCH lower at about 23,000 miles above the Earth.
Thus yes, the clocks will go faster because the warp of space-time dimensions will be less in comparison
to the clocks at the deeper warp near the surface of the Earth.
Of course the difference is in milliseconds, but this is significant in GPS and telecomm packet transfer.

Not only did I know this because I was a Physics major and have been working with this branch of science for over 15 years, but also I worked as an analyst consulting the engineers for SPAWAR at the GPS library in San Diego for a year. And now I'm an analyst at a Satellite Telecommunications firm where one of our features for our mobile modems is GPS off the MSAT geostationary satellite.

Last edited by rogue49; 06-04-2003 at 05:48 PM..
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Old 06-05-2003, 02:39 AM   #9 (permalink)
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Quote:
Originally posted by BentnotTwisted
duckznutz,
The flashlight thing is explained by light frequency shift. If I am moving quickly towards a red light it will shift up the frequency to green, blue and eventually out of the visible spectrum. If I am moving away from a light source at a high velocity it will shift down in frequency. If you are a trekkie you can see the effect out the windows when the ships are travelling at warp. Stars are stretched out over the full visible spectrum of light from red to blue, very cool.

Yes I understand the red-shift and the doppler effect . . . but that doesb't explain that the SPEED of light moving away from me = the speed of light BUT if I am on a train moving away from the station at 100mph then the speed of light from my torch is moving away from the station at the speed of light PLUS 100mph . . is this right? . . . anyone?
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Old 06-05-2003, 04:14 AM   #10 (permalink)
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No
the speed of light is constant.
Which means that it is moving at C (in a vacuum, water and other mediums will alter this speed slightly)
This means that it will just take the light longer to get to the station for each moment traveling away.
Which is why when we are looking at the stars we are seeing into the past.
Light only goes so fast, thus by the time the light gets to us, it's representing something that got emitted years ago.
So the light getting to the station would be C, C+t, C+t+t2, C+t+t2+t3...or C+tn
"n" for whatever time it has been since the train left the station. (sorry, I couldn't find a summation character)
But this does NOT represent the velocity of light when it hits the station, it will still be C.

Only with an increase or decrease in velocity of the train, will the light shift wavelength (red or blue, respectively)
Which is why scientist are saying the universe is expanding, or the stars moving away from us with increasing velocity,
thus the red-shift.

Last edited by rogue49; 06-05-2003 at 04:29 AM..
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Old 06-05-2003, 01:01 PM   #11 (permalink)
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. . . . I really appreciate you taking the trouble to reply . . . . . . sorry for not understanding it all . . . but in my last thread I was imagining that I was shining the torch FORWARDS as I was on the train . . that is to say, the light was shining AWAY from the station. By my logic . .if aphoton light is moving away from ME at the 'speed of light' . . and I am moving away from the station at 100mph . . then the photon is moving away from the station at the speed of light PLUS 100mph? . . .
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Old 06-05-2003, 03:12 PM   #12 (permalink)
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No,
it's still at a constant speed.

It wouldn't matter if you were moving at 100, 1000 or 10000 mph
The speed would still be C

BTW the Speed of Light in Vacuum is 299,792,458 meters per second or about 186,000 miles per second.
Interestingly, the orbital speed of the Earth is about .01% the speed of light. Add in that The Sun is revolving around the center of the Galaxy, with an orbital velocity of about 200 miles per second. This is about .1% the speed of light. (That's damn fast)

A good link describing your question & validating my answers.
http://www.physlink.com/Education/AskExperts/ae558.cfm

Last edited by rogue49; 06-05-2003 at 03:16 PM..
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Old 06-05-2003, 05:54 PM   #13 (permalink)
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At this point the little old lady bumps in and says, "It doesn't really matter because the whole universe is sitting on the back of a turtle."

"But what is that turtle sitting on?"

"You're very clever, young man, very clever. But it's turtles all the way down."
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Old 06-06-2003, 01:52 AM   #14 (permalink)
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Has anyone considered that *time* is not a fundamental property of the universe? Excuse me for saying, but I think that may pose a problem for General Relativity. Several equations become unsolvable or moot without time - probably related to the fact that they also break down under quantum theory.

In my (unprofessional) opinion, time is nothing more than an arbitrary frame of reference created by mankind to describe his surroundings, particularly motion, velocity, and the like. IF you accept that the universe is infinite; then it seems to me that motion and velocity are irrelevant.

Any attempt to describe inherent properties of the universe (or anything else for that matter) by using any variables or reference to anything other than fundamental properties of the universe are doomed to fail. In other words, the references must be made to a property that is not subject to interpretation based on frame of reference; mass for example.

Interestingly, when you attempt to describe mass at relatively high velocities (approaching the speed of light) it appears that mass increases, becoming infinite AT the speed of light. To me, that's because SPEED is a function of time and thereby the reference is flawed.

Anyway - enough for now, anyone else with more sense than me want to take a crack?
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Old 06-06-2003, 03:51 AM   #15 (permalink)
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*scratches head - perplexed* Thanks rogue 49 . . but I still dont get it . . . maybe need to check a few text books or something . . . . . the speed of light is 'c' you say . . . but relative to what? everything? If you shine two torches towards each other are you saying that the photons 'know' that there is another photon coming straight at it . . and so it slows down to half its normal speed to ensure their closing speed does not exceed 'c'? DOH! I dont get it! No need to reply rogue49 . . its my stupidity not yours . . I will go read up on it. Thanks
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Old 06-06-2003, 03:53 AM   #16 (permalink)
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Quote:
Originally posted by shadrock
At this point the little old lady bumps in and says, "It doesn't really matter because the whole universe is sitting on the back of a turtle."

"But what is that turtle sitting on?"

"You're very clever, young man, very clever. But it's turtles all the way down."

Do you mean the animal the turtle? Or is this a code name for some interstellar phenomenon? I know there are great bears and ploughs and so on but I have never heard of the turtle.
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Old 06-06-2003, 05:32 AM   #17 (permalink)
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duckznutz, he means a "real" turtle. He was referring to an ancient myth
that said the universe sat on the back of a very large turtle,
and that turtle sat another and so on.

BTW, the photons don't "know", they just move straight at a constant rate. "C" represents this rate or speed.
The only thing that affects this is gravity which changes or bends the path it's taking
or it goes through a different material, like water or glass.

tiberry
Time is a fundamental aspect of the Universe - a Dimension we live within.
Currently there are 4 accepted Dimensions, 3 spatial and 1 time.
Personally, I think there are more, but that's a whole other thing.

Time is a measurement of "Action".
Yes, Mass can be something that is used for measurement,
and that affects the 3 spatial Dimensions (up/down, left/right, backwards/forwards or X,Y,Z in graphing),
and how much material is within that area (density)...
However, there are things "happening", everything is not just sitting around.
You need to account for this in the Dimensions you live within...thus Time.
Even when something is sitting still, something is happening.
Atoms are moving, light is moving, you're observing.

You have to account for the action & interaction of all.
There is not just one object or point in the Universe.

Now you might be correct in the scientists might be going the wrong way with their models,
and not taking everything into account,
but for the most part Time is pretty much a given.

Last edited by rogue49; 06-06-2003 at 05:41 AM..
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Old 06-06-2003, 07:51 AM   #18 (permalink)
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Ahhhh...a taker!

And what better place for a debate than in the philosophy forum, where neither of us could ever really be wrong...

Don't take it personally- but I'm going to deconstruct your reply systematically - all in the name of a good debate.

You say that time is a fundamental aspect of THE universe - I'll give you ...fundamental aspect of OUR universe, or in other words the way we describe THE universe.

Let me refine my statement - Time is not an ELEMENTARY property of the universe.

I can't say that I agree completely that time is a measurement of action. In the simplest sense, yes...but again - it depends on your point of reference. In order to quantify movement one must state "at point x in time the object was there, at point y it is now there...therefore the object has moved. BUT, moved in reference to what?

Mass is more elementary. It exists whether we measure it or not. Notwithstanding the tree in the forest postulate of course...but even if we did measure it, we don't need a reference in order to deduce that the mass exists.

You say that time is a dimension, that is correct. Time is a measurement just as X, Y, Z, velocity, and many possible others. Precisely my point: Time is not a PROPERTY it is the MEASUREMENT of a property.

Relativity is very intriguing to me, as it seems to be the "on the right track", just incomplete. It becomes very difficult to imagine how to accurately describe things without a reference point RELATIVE to what you're measuring. You're intended counter to my statement actually did very well in proving my statement.

***There is not just one object or point in the universe.****

Just for a moment, imagine yourself 'outside' the universe, you are some 0 dimensional being. As such, you need no frames of reference to perceive or describe your surroundings. What would you see?
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Old 06-06-2003, 02:14 PM   #19 (permalink)
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some explaination from Back To The Future:

the dog has a stop watch that is in sync with the doctors. the dog is sent exactly one minute into the future. one minute later the doctor sees the car with the dog in it. The watch on the dog is exactly one minute behind the doctors. from the perspective of the DOG the travel was INSTANTANEOUS. for the doctor it took a minute for the dog to get there.

yes u are right it is from a movie but thats how we understand this. it's that you SKIP over that time (going through the space/time continum).

relativity and such is very complex and most people cant or dont want to understand such complex things.

how i understand it is that the 4th dimension is the space/time relationship (whatever u wanna call it).

the 4th dimension CONNECTS two of the other three dimensions WITHOUT intersecting the third dimension.

time is directly connected to space by something we cant see or really understand yet but as far as I understand, thats how it is.

-= if you wanna understand more keep reading =-

now to understand this more, if any of you want to, check out "Klein's Bottle" this is a 4D shape/figure that can be rendered in 3D (not completely but effectively) to help explain and visualize the 4D relationship.

something simple: you walk through a giant tube and you end up standing exactly where u started but on top of the tube.
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Old 06-07-2003, 07:55 AM   #20 (permalink)
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Well tiberry, first we are not really doing philosophy but science,
so there is as much a quantitative as qualitative background, and one of us could be wrong.

And you cannot judge what is absolutely true, you can only judge what you know.
Everything we know is based on how we define it.
And as our tools & knowledge base grows so does our knowledge,
so let's only base it on pertinent knowledge otherwise we could argue to infinity.
And that is essentially worthless.

Second, all dimensions ARE elementary properties of the universe.
By its definition, it is what we are working in.

Third, you have to have a reference to something, again otherwise it is essentially worthless
Something existing by itself, is just a point.
And it has to do something, it is just a point and again worthless.
And please don't tell me that a point by itself is worth something.
Because it all depends on the scale,
anything in a Void is Infinity.
You have to have a duality, it is essential to existence.

So, since we have eliminated the possibility of a single point,
and non-active particle with no point of reference.
We now have space & time.
A dimension to HAVE something in.
A dimension to DO something in.
That IS fundamental if I've ever seen the word.

BTW, if you are measuring something, YOU are the reference.

ANY mass has to have a space & a time.
These are aspects of our universe, and mass affects what is in, and vice versa.
Thus Gravity, which is NOT a Force, but a warp in Space & Time, the Dimensions it sits in.
We feel this, it affects its surroundings.
This is why we can treat it AS IF it was a Force.
This is fundamental, and this HAS been tested again & again.

Thus it IS a property of the universe, and NOT just a measurement.

And you are correct, on one point...the Theory of Relativity is incomplete.
And since Dimensional Theory is my specialty, and this is what I've based much of my own work on,
I've realized this...it needs to be expanded.
There is more than just space & time
as dimensionals aspects of this universe, the definitions need to be broadened and added to.
Hopefully, I can prove this in the future.

BTW, there would be no such thing as a 0 dimensional being outside the universe,
because once you have that entity you are back to it taking up some space & time.
It doesn't matter to what scale you are referring to.
I think, therefore I am.
Any existence, any consciousness is being, thus there is space & time.

First you have 0, the void, nothing, and thus essentially worthless.
Then you have 1, a point, this is just mathematical, and again essentially worthless.
(if it has ANY mass, then you've got space & time, and even at an infinitesimal scale, a universe)

But back to 2, a line, again this is just mathematical, a scale now, which can interact.
(this is an essential aspect, you have to have SOME point of reference, otherwise worthless)
You now have time & probability come into play. Because at ANY scale or interaction, there are these.

And now to 3, a plane, this is also just mathematical
And finally 4, a solid, this is when you get to ANY type of mass.

Thus your statement that mass is more fundamental is incorrect.
You have to get to two steps further from where the idea of Time comes into play,
before you get to substance.

You HAVE to have the Dimensions, before you have the Mass.
And they both affect each other.

And your own idea of a "being" outside OUR universe,
obviously doesn't have mass,
but it does have SOME dimension,
it IS within something.

Hopefully, this clears things up.

Last edited by rogue49; 06-07-2003 at 08:18 AM..
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Old 06-07-2003, 08:54 AM   #21 (permalink)
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Doesn't superstring theory dictate that our universe has either 10, 11, or 23 dimensions? I was under the impression that each dimension has curled dimensions that we don't fully perceive.
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Old 06-07-2003, 07:28 PM   #22 (permalink)
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I am going to have to disagree with Rogue49's earlier statement that "The Speed of light is constant" The speed of light is in fact not constant, but it does have a maximum value. That maximum value is known as C, but Light can be slower. Simply pass light though any object with an index of refraction greater than 1 and light is slowed. We know this because the measured frequency in the object is constant, but the wavelength of light changes. Using the equation velocity=frequency*wavelength, we find that with a constant frequency, a decrease in wavelenth will propagate to a decrease in velocity.

Isn't relativity fun!
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Old 06-07-2003, 11:24 PM   #23 (permalink)
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Yes, superstring theory (one of the proposals for the Universal Theory) does say that.
However I believe they are off track in stating there are "curled" or "shrunken" dimensions.
I believe there are actual Dimensions that have yet to be defined or proven.
This is one of the things I am working on.
It's going to "fun" to prove.

RatherThanWords
Take a look again.
Actually, I DID state that light would slow down slightly in a different medium. (such as glass or water, etc)
Which is why when I referred to the speed, I said, "in a vacuum".
It is not constant, but it is a "Constant".
Different definition.
Whenever you want to take an exact measure,
you should try to do it in a vacuum
Otherwise your measurement is altered by the enviroment.

Last edited by rogue49; 06-07-2003 at 11:29 PM..
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Old 06-09-2003, 06:02 PM   #24 (permalink)
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Quote:
Originally posted by RatherThanWords
I am going to have to disagree with Rogue49's earlier statement that "The Speed of light is constant" The speed of light is in fact not constant, but it does have a maximum value. That maximum value is known as C, but Light can be slower. Simply pass light though any object with an index of refraction greater than 1 and light is slowed. We know this because the measured frequency in the object is constant, but the wavelength of light changes. Using the equation velocity=frequency*wavelength, we find that with a constant frequency, a decrease in wavelenth will propagate to a decrease in velocity.
Not quite.

There are two explanations for why you're wrong here. The speed of light postulate states that the speed of light is a constant in a vacuum. That's what Einstein said. An object with a refraction of more than 1 is not a vacuum.

Or, using what we've learned since, light doesn't actually slow down in these substances. instead, it is annihilated when it strikes atoms and is forced to slow down. In turn, its energy then creates more light at the same frequency. The time this takes gives the impression that light is slowing down, when in fact it is just being created and destroying many times, but always travelling at c when in existence.

Or you could just go with those substances not being vacuums, since my terminology is probably way off for the second explanation.
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Old 06-09-2003, 09:24 PM   #25 (permalink)
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I have no education to even begin to post here but forgive me in advance. This whole time thing, can a significant time change be noted when the speeds do not even come close to light speed. Trying to get away from hypothetical situations but if my watch was precisely set with someone else’s watch and they drove at 60 mph for a long trip and I did not would they have a noticeable time difference then my watch?
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Old 06-10-2003, 03:11 PM   #26 (permalink)
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Quote:
Originally posted by freedomdowntime
I have no education to even begin to post here but forgive me in advance. This whole time thing, can a significant time change be noted when the speeds do not even come close to light speed. Trying to get away from hypothetical situations but if my watch was precisely set with someone else’s watch and they drove at 60 mph for a long trip and I did not would they have a noticeable time difference then my watch?
No, you have to be going really fast. We wouldn't notice much of a change unless someone went at near c, and for a significant enough amount of time.
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Old 06-10-2003, 05:06 PM   #27 (permalink)
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Quote:
Originally posted by Tom Thumb
No, you have to be going really fast. We wouldn't notice much of a change unless someone went at near c, and for a significant enough amount of time.
That's not true either,
they've done testing with speeds at super-sonic level.
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Old 06-10-2003, 08:01 PM   #28 (permalink)
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So, tell me if I understand this correctly. Speed affects time?
Another dumb question I have is if someone is going fast aroung in a circle is it the same as if they are going on a plane in flight as far as the affect on time goes given that the speeds are the same.

It would be great to experiment with these concepts but I can't cheaply reach super-sonic speeds.
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Old 06-14-2003, 06:03 AM   #29 (permalink)
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I think we may need some mathematics to clear up some questions. The following are called Lorentz transformations, they can be used for all properties of coordinate systems x, y, z, and time,t , but I am just going to include the transformations for time, t, since this seems to be a point of confusion.

t is time as it passes for the observer which is assummed to be at rest (galileian body) and t' is time for another object, person, coordinate system that is moving relative to us with time t. In order to find how time passes for this other object we can use this equation:

t'=[1-(v/c)]t/[sqrt(1-(v^2/c^2))]

where v is velocity of the obect, as it appears to us, t is time elapsed for us, sqrt is the square root. c is the constant for the speed of light or 300,000 km/sec.

What this equation shows is that for a light particle time has no significance because 0/0 is indeterminate. You can use this equation to see how slow time is moving for that car speeding 120 miles down the road.
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Old 06-14-2003, 08:15 AM   #30 (permalink)
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Heh,

Glad to see you guys are having fun

Isn't relativity a blast??
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Old 06-15-2003, 05:18 PM   #31 (permalink)
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Quote:
Originally posted by rogue49
That's not true either,
they've done testing with speeds at super-sonic level.
I was replying to the question of whether there would be a 'significant' change. At 60 mph the changes would be in the milliseconds.

Lebell: Yep.
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Old 06-16-2003, 03:03 PM   #32 (permalink)
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I must be a bit slow because I am still not getting this . . . . so becuae it has taken a while for the light to get here . . . . the stars i see in the night sky are really the stars that were there 2000 years ago (around the time of Jesus birth?) . . and they do not actually exist where I currently see them? So if an alien signal was recieved from that distance it would be from aliens from 2000 years ago?

But to all intents and purposes we might as well simply accept that the stars we see ARE actually there . . . (even though they are not) . . . . which then means that nothing actually exists beyond a certain distance from us?

Yeah . . that all makes sense . . . maybe god existed 2000 years ago and now doesn't?
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Old 06-16-2003, 10:30 PM   #33 (permalink)
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yes the light you see from stars is millions of years old the closest star is 4.2 light years away but some range in the 100,000's
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Old 06-19-2003, 06:14 AM   #34 (permalink)
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The closest star is eight minutes away,if u travelled at the speed of light.
Isnt the speed of light relative?
If gravity can bend light,the way it does when we observe stars close together,wouldn't it travell further and be measured as being slower than if it had travelled in a "straight line"?
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Old 06-19-2003, 07:17 AM   #35 (permalink)
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I am getting the idea that our perception of time is only valid for things relatively near to us. Stars and stuff exist in a different timeslot to the one we are seeing them in.
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