Can the Speed of Light Be Changed and What Does It Mean for Space Exploration?

[russ_watters]

Time contraction is also an illusion. Time only seems slower at high velocities, because our eyes can't measure things as fast as it can moving at non-relativistic speeds. This lag in the eye's calculation gives the illusion that time is running slower.

How do our eyes effect the tick rate of clocks on GPS satellites?

They are measruing wrong.

Explain this: are you saying that every scientist who accepts the validity of Relativity is wrong? Are you saying every scientist who uses it is wrong?

GPS satellites have their clock tick rates calibrated according to Relativity prior to launch. This allows the clocks to stay in sync with clocks on the ground. How is this possible if the scientists are screwing up? Dumb luck?

As others have noted, you can program a computer to do all of this for you and give you the answer: how can human eyes affect the operation of computers?

employee #416, do you realize the implications of what you are saying? Its absurd. This whole issue boils down to you refusing to accept reality at face value because you don't like how reality is.

 

[bino]

i understand what each of you is saying. both sides make very good points. some sides better points than others. you have to keep in mind that the length contracts only from the point of view of the stationary object. that's where the disagreement comes from. the ship looks shorter because it is shorter from the point of view of the lattes. the measurements from the equipment are correct from their point a view. the measurement are taken from a point in time. at that point in time the ship will measure to be shorter than its real length. but from the point of view of the ship it length has not changed so the equipment on the ship will say that same thing that it is in fact the same length as when it was stopped. it all matters on the point of view.

 

[Nenad]

hence the name 'relativity'

 

[quantumdude]

Heh, don't babble to me about what I'm denying and what I'm accepting. In the end, you are right though.

The only one here babbling is you.

Time contraction is also an illusion. Time only seems slower at high velocities, because our eyes can't measure things as fast as it can moving at non-relativistic speeds. This lag in the eye's calculation gives the illusion that time is running slower. This may not be relevant, but I'll take a stab at it. Turn on a strobe light. How does everything look in motion? Slower than it actually is, eh? Our eyes are tricked. We measure things only if visible. If things go in and out of visiblity the eye measure slower than normal. This is an illusion, but we know that time is the same, right?

I repeat: Our eyes have nothing to do with it. When time dilation is measured in muon decay, the time of creation is recorded, and the time of decay is recorded. The particle lives longer in the lab frame than it does in its rest frame. And no, the decay is not too fast for the equipment.

Particle phyisicists use time dilation every day to prolong the lifetime of unstable particles so that they can study them. But once again, here you are, the arrogant, ignorant internet bozo, thinking that you know better than the people who work with it every day, when you have never even studied it once.

How can we rely on equations, that are derived from methods our eyes use for measurements? Our eyes do not measure everything accurately. If something is too fast for our eyes to measure, our eye distorts it. If an object is not moving, our eye is not accurate in measuring any dimension of that object. It's all estimated, until a tool for measuring is pulled out for clarity.

Our eyes don't take the measurements in modern physics. Why are you ignoring me?

An object has a length of 100cm.

Correction: An object has a length of 100cm in its rest frame.

It is traveling at relativistic speeds. Let's make that speed .95c. It appears to be shorter or is shorter?

It is shorter in the frame of the person watching the object fly by. It is still 100 cm in its rest frame.

I'd go with the former.

No one cares what you would go with. All experimental confirmations of SR contradict you.

That's why you are a crackpot.

Length does not just disappear into thin air.

The universe is not oblgated to behave according to your preconceived notions.

The true length will ALWAYS be there.

Correction: There is no "true length" of any object.

The time experienced by that moving object is the same as a person in a difference reference frame. It just seems slower.

No, it is slower.

No, I'm going to correct you.

Again, your arrogance is absolutely staggering. What on Earth makes you think you know anything about this? You have very clearly not studied it.

It only appears to be shorter. The physical length of an object traveling at relativistic speeds is always there.

Wrong. There is no preferred frame of reference, and so there is no true "physical length" of an object. You are just clinging to a faulty view of space and time that was used by Newton and is now known to be false.

By true lenght, I'm referring an object measured while on the ground or table.

That is called the proper length, but there is nothing special about it. The idea of the length of an object has no meaning apart from specifying its state of motion.

They are measruing wrong. No length is lost due to motion. That's just stupid.

Oh, well now I'm convinced.

I'll just scrap all of those experimental tests of relativity because, "that's just stupid".

Learn to formualte an argument, kid.

Magically that length returns when an object is decelerated to non-relativistic speeds. No, it was always there.

Wrong. The length contraction formula applies at all speeds, not just relativistic speeds.

I'm pretty sure this has to do with the human eye.

I've already told you this is wrong, so the question is, why the hell are you persisting in it?

TRIANGLES! The whole formula is derived from the transformation of triangles.

You are hopeless.

First, you ask me for a link that contains the derivation of these phenomena, and I gave it to you. You have obviously not even looked at it, because it very clearly shows how the Lorentz transformation is derived from the postulates of relativity and Maxwell's electrodynamics.

"TRIANGLES!" Pfffft. Get a clue.

I'm pretty sure if you were to mess with it, you could get at the method the human eye uses to measure things.

I'm absolutely sure that you have no idea of what you're talking about.

Why is it an eye trick?

It isn't an eye trick.

Ok, take an object with two points. The point at the head end is point A, while the point at the back end is point B. This object, at rest, has a length of AB. Give this object a velocity that is non-relativistic, and your eyes notice no drastic affects in measuring the length. Give it relativistic speeds, and your eyes notice a huge difference. When it tries to calculate the distance from A to B it is smaller than what the distance is at rest. When point A crosses the eye, almost immidiately point B crosses the same path A has just crossed. Thus making measurment SEEM contracted. No length contraction is taking place.

Wrong. Look at the Lorentz transformation, and you'll see no reference is made to human eyes, human minds, or the means of measurement.

You keep posting this same garbage, and I keep telling you that it is not reflective of relativity at all. Why do you do that? It is just not rational. You say that you want to be a member of this Forum, and you know that we do not allow unsubstantiated nonsense here. So why is that all you ever post? It makes no sense.

 

[quantumdude]

Minor nitpick - these two statements contradict each other: I know what you mean, but I think it may be less confusing to others if the second statement read 'every measured length of objects is "real."' You mean there is no single real length and a bunch of illusions.

OK, I'll explain.

If something is measured to be shorter, then it is shorter. Measurements are what tell us what is real.

And this is what is "real": The length of an object is depends on its state of motion relative to an observer. It is not a determinate quantity until its state of motion relative to an observer is specified.

...there is no "real" length of objects.

Meaning that since the length of an object is determined by its state of motion relative to an observer, and since there is no preferred reference frame, it cannot be said that the length measured in any reference frame is any more "real" than that measured in any other frame. All reference frames have an equally valid experimental point of view.

 

[Nereid]

Note: some people *think* they may have found a change in the fine structure constant. This hasn't been widely accepted, and the magnitude of the supposed change is very small - on the order of .001 percent. Not enough to fuel any visions of "galactic superhighways" even if it is true (and it's probably just a very small measurment error of some sort).

AFAIK, there are two types of observation which have been done, to see if alpha is varying over cosmological time (roughly, billions of years) - Oklo and astronomical. The former refers to a natural reactor, in uranium ore in Africa; from an analysis of the decay products, alpha has been shown to be constant to 1 part in 10 million, over a billion years or three. The astronomical observations are of several kinds; the most accurate - in several senses - show that alpha has not changed by more than 1 part in ~100,000, over ~10 billions years. There were some earlier studies, with lower accuracy, which could be interpreted as evidence for a small time variation; these observations used a technique that requires a rather long chain of calculations and many inputs (so the results were always in some doubt).

employee #416, I see that you have a different opinion from many other posters here; can you point to experimental evidence that supports your opinion? In particular, how are the muon decay experiments, and the actual functioning of the GPS system consistent with your opinion? No hand-waving please, just the numbers and the math.

 

[Alkatran]

Oh fun fun, crackpot smashin time

Heh, don't babble to me about what I'm denying and what I'm accepting. In the end, you are right though.

Time contraction is also an illusion. Time only seems slower at high velocities, because our eyes can't measure things as fast as it can moving at non-relativistic speeds. This lag in the eye's calculation gives the illusion that time is running slower. This may not be relevant, but I'll take a stab at it. Turn on a strobe light. How does everything look in motion? Slower than it actually is, eh? Our eyes are tricked. We measure things only if visible. If things go in and out of visiblity the eye measure slower than normal. This is an illusion, but we know that time is the same, right?

Maybe things appear to go slower lalalla bu it doesn't matter: The effect is getting larger. The objects continue to move slower/faster through time and the gap between them increases. Think of two clocks, one is stationary and one is moving at near lightspeed. Let's say when they're a lightyear apart, they're synchronized (in the rest frame with Clock 1, of course). By the time Clock 2 meets Clock 1, Clock 2 well have a few extra days, maybe a few extra years, depending on the speed, on it. Is that still an optical illusion? I've never seen an illusion that could rotate a clock hand 360 degrees.

How can we rely on equations, that are derived from methods our eyes use for measurements? Our eyes do not measure everything accurately. If something is too fast for our eyes to measure, our eye distorts it. If an object is not moving, our eye is not accurate in measuring any dimension of that object. It's all estimated, until a tool for measuring is pulled out for clarity.

I can guarantee you they don't use human eyes to measure particles inside a particle accelerator. There's a big slab of matter (metal?) in the way.

An object has a length of 100cm. It is traveling at relativistic speeds. Let's make that speed .95c. It appears to be shorter or is shorter? I'd go with the former. Length does not just disappear into thin air. The true length will ALWAYS be there. The time experienced by that moving object is the same as a person in a difference reference frame. It just seems slower.

Haha, just saw your post Tom Mattson.

No, I'm going to correct you. It only appears to be shorter. The physical length of an object traveling at relativistic speeds is always there.

By true lenght, I'm referring an object measured while on the ground or table.

In a way this is true, an object can never be longer than its proper length.

They are measruing wrong. No length is lost due to motion. That's just stupid. Magically that length returns when an object is decelerated to non-relativistic speeds. No, it was always there. I'm pretty sure this has to do with the human eye. TRIANGLES! The whole formula is derived from the transformation of triangles. I'm pretty sure if you were to mess with it, you could get at the method the human eye uses to measure things.

I like the "TRIANGLES!" remark, which clears up the whole thing for me.
Just so you know, the length is always "there", the problem is that you're looking at the object skewed through time. I'll include a link for a nice explanation of this at the bottom of this post.

Why is it an eye trick? Ok, take an object with two points. The point at the head end is point A, while the point at the back end is point B. This object, at rest, has a length of AB. Give this object a velocity that is non-relativistic, and your eyes notice no drastic affects in measuring the length. Give it relativistic speeds, and your eyes notice a huge difference. When it tries to calculate the distance from A to B it is smaller than what the distance is at rest. When point A crosses the eye, almost immidiately point B crosses the same path A has just crossed. Thus making measurment SEEM contracted. No length contraction is taking place.

But this effect would be reversed if you measured B followed by A, making the object appear longer.

This is probably all jumbled up...I have school in 2 hours and I haven't slept, so whatever.

Don't worry about the lack of sleep, it would be jumbled anyways.

http://casa.colorado.edu/~ajsh/sr/paradox.html

 

[bino]

lets say there is a star 44000 lightyears away. how long will it take to get there going light speed?

 

[Doc Al]

lets say there is a star 44000 lightyears away. how long will it take to get there going light speed?

Assuming that you mean that according to Earth-frame measurements the star is 44000 lightyears away, and that you are sailing by in a rocket at close to c (say 0.99c with respect to the Earth): the distance as seen by you in your rocket frame will be contracted--and it will take you about 6270 years to get there according to your rocket-frame clock.

 

[bino]

how long from Earth's point of view?

 

[Alkatran]

how long form Earth's point of view?

44 000 years, of course. (well, approximately, the Earth is rotating around the sun which is rotating around the galaxy...)

 

[Nenad]

Assuming that you are going at o.99c. In Earth's point of view, they will see your trip takes:
$$t_o = t\sqrt{1 - v^{2} /c^{2}}$$
$$6270y = t\sqrt{1 - 0.99c^{2} /c^{2}}$$
$$\frac {6270y}{0.141} = t$$
$$t = 44468 years$$

 

[bino]

does light have mass?

 

[Nenad]

light has no rest mass. It has relativistic mass, and momentum.

 

[bino]

where did you get 0.141?

 

[Nenad]

$$6270y = t\sqrt{1 - 0.99c^{2} /c^{2}}$$
$$6270y = t\sqrt{1 - 0.9801c^{2} /c^{2}}$$
$$6270y = t\sqrt{1 - 0.9801}$$
$$6270y = t\sqrt{0.0199}$$
$$6270y = t(0.141)$$
$$\frac {6270y}{0.141} = t$$
$$t = 44468 years$$

 

[bino]

what is lights relativistic mass?

 

[bino]

$$6270y = t\sqrt{1 - 0.99c^{2} /c^{2}}$$
$$6270y = t\sqrt{1 - 0.9801c^{2} /c^{2}}$$
$$6270y = t\sqrt{1 - 0.9801}$$
$$6270y = t\sqrt{0.0199}$$
$$6270y = t(0.141)$$
$$\frac {6270y}{0.141} = t$$
$$t = 44468 years$$

got yeah! that makes sense.

 

[Nenad]

listen, bino, I am not going to sit here and spoonfeed you all night, look it up on a google search, or on another forum. Trust me, its a lot better than asking me 1000 questions and its a lot faster. Sorry for the outburst.

 

[Doc Al]

Assuming that you are going at o.99c. In Earth's point of view, they will see your trip takes:
$$t_o = t\sqrt{1 - v^{2} /c^{2}}$$
$$6270y = t\sqrt{1 - 0.99c^{2} /c^{2}}$$
$$\frac {6270y}{0.141} = t$$
$$t = 44468 years$$

Perfectly correct, of course, but the simplest way to look at it from the Earth's viewpoint is $t = D/v = 44000/0.99{ yr} = 44400{ yr}$.

 

[quantumdude]

Bino,

Physics is best learned by working out problems. You're obviously curious and interested, and I think you'll benefit from this:

Special Relativity

It's an excellent textbook in relativity, and it's free.

 

[bino]

ok hypothetically, if i were in a ship that was going the speed of light. how long would it take to get to that star 44000 lightyears away? from the point of view of the ship.

 

[quantumdude]

ok hypothetically, if i were in a ship that was going the speed of light. how long would it take to get to that star 44000 lightyears away? from the point of view of the ship.

It wouldn't take any time at all from that point of view. As Einstein said, the speed of light plays the role of an infinitely great speed in SR.

 

[bino]

how is it that we can measure the speed of light if it doesn't take any time for it to get from one place to another?

 

[Chronos]

how is it that we can measure the speed of light if it doesn't take any time for it to get from one place to another?

It does take time for light to travel any distance, unless you are a photon. In which case time and space cease to exist. Ordinarily, I would ask what part of relativity do you not understand. In this case, I would say the answer is all of it.

 

[what_are_electrons]

This thread seems to contain a lot of hypthetical ideas akin to theories. How has it survived? Perhaps the speed of our Mentors has dropped out of light speed.

 

[ArmoSkater87]

light has no rest mass. It has relativistic mass, and momentum.

Actually light can't have relativistic mass because of SP equations...
$$m = \frac{m_0}{\sqrt{1-\frac{v^2}{c^2}}}$$

As you can see, if something has a rest mass($$m_0$$) of zero, then the relativistic mass is zero as well because zero divided by anything is zero.

It wouldn't take any time at all from that point of view. As Einstein said, the speed of light plays the role of an infinitely great speed in SR.

Lightspeed is a constant finite speed, I thought this was the basis of SR.

Or is it because this...
$$u' = \frac{u+v}{1-\frac{uv}{c^2}}$$
The light from the star coming towards u at c, and you going towards it at c

$$u' = \frac{c+c}{1-\frac{c^2}{c^2}}$$
$$u' = \frac{2c}{0}$$
$$u' = infinity$$

 

[quantumdude]

This thread seems to contain a lot of hypthetical ideas akin to theories. How has it survived? Perhaps the speed of our Mentors has dropped out of light speed.

Those who are politely asking questions are being accommodated.

Those who are rudely making unscientific assertions have been banned.

Does that answer your question?

 

[quantumdude]

Lightspeed is a constant finite speed, I thought this was the basis of SR.

Or is it because this...
$$u' = \frac{u+v}{1-\frac{uv}{c^2}}$$
The light from the star coming towards u at c, and you going towards it at c

$$u' = \frac{c+c}{1-\frac{c^2}{c^2}}$$
$$u' = \frac{2c}{0}$$
$$u' = infinity$$

No, that's not an equation of relativity (if you're adding in the numerator, you should adding in the denominator, and the same goes for subtracting).

"c" plays the role of an infinite velocity because it is unattainable.

Actually, while the above statement is true, I shouldn't have said that it "takes no time at all" for light to travel a distance, because SR actually makes no predictions about what happens at light speed. So I officially withdraw that comment.

 

[quantumdude]

how is it that we can measure the speed of light if it doesn't take any time for it to get from one place to another?

You have to be careful. I said that "it takes no time at all", meaning that it takes no time in the reference frame of the light. In the lab frame however, it takes a finite time, and the speed of a light pulse is easily measured by recording the position of emission, the position of detection, and the time interval between those two events.

But as I just said to Armo, I should not have said that "it takes no time at all" in the photon frame, because SR actually makes no predictions on the experimental results obtained from the photon frame. The time it takes to traverse a distance is actually undefined.

 

[bino]

ok. from the view point of the lattes the ship has compressed because the ship is moving so fast, but from the view point of the ship the lattes is the one that is going by so fast and that is why the lattes is compressed. correct? so then from the view of light we would be moving that fast. so then from the frame of light we would be compressed. how can this be?

 

[Nenad]

? Read the book posted a while ago about special relativity. It helps a lot. If thwo abjects are in the same frame of reference, (travelling at the same speed in the same direction) then they see no difference in themselves. There is no dilation or compression.

 

[quantumdude]

ok. from the view point of the lattes the ship has compressed because the ship is moving so fast, but from the view point of the ship the lattes is the one that is going by so fast and that is why the lattes is compressed. correct?

Not really. I kept saying before that nothing actually happens to either the ship or the rod. It's not as if some physical force is pushing on them to cause them to be shorter. They simply are shorter in other frames of reference.

so then from the view of light we would be moving that fast. so then from the frame of light we would be compressed. how can this be?

As I said, SR makes no predictions about what would be seen from an inertial frame moving at speed c. The Lorentz factor is undefined there. We can talk about things that happen in inertial frame as its speed approaches c, but if you want to keep talking about frames that move at the speed of light, then SR has no answers for you, and so neither do I.

Now if you want to talk about frames moving with speeds less than c, we can get somewhere.

 

[bino]

but from the frame of reference of the light we would be the ones moveing at the speed of light. right? you know when your driving in a car the objects closer tothe car look like there are moving faster than the objects farther away. idont remember what that's called but why doesn't that have an effect on the Lorentz equation?

 

[russ_watters]

but from the frame of reference of the light we would be the ones moveing at the speed of light.

bino, Tom just said under SR, there is no such thing as "the frame of reference of the light."