Speed of light is limited by what?

[Southtown]

Don't try to talk down to me, ding-a-ling. What part of Lorentz covariant 4 vector formulation of dynamics, light cones, and Minkowski do you not understand? Perhaps I can help.

HAHAHA - Funniest thing I've ever heard.

 

In short, it depends of how you want to look at it.

And the truest thing I've ever heard.

[Bobby]

HAHAHA - Funniest thing I've ever heard.

 

 

And the truest thing I've ever heard.

 

 

 

Most of the time I'm a very patient person. Sometimes, I'm not. If you can only see things one way, science is probably not for you.

[Qfwfq]

These boards are not the place for name calling, Bobby. Perhaps you should have another look through the rules:

 

http://hypography.com/forums/?page=rules

 

What part of Lorentz covariant 4 vector formulation of dynamics, light cones, and Minkowski do you not understand? Perhaps I can help.

If you were able to help others on these things, I think you would be showing more understanding of them in this thread. You gave the impression you were asking help to understand something and I began by suggesting what is useful for a better understanding. Your reaction doesn't show the greatest maturity.

 

Either ask for help and respect the response you get, or help others if you're able to. In any other case these boards aren't the right place.

[EWright]

CAN NO ONE PROVIDE A SUFFICIENT ANSWER TO THE ORIGINAL QUESTION??? :)

[Bobby]

CAN NO ONE PROVIDE A SUFFICIENT ANSWER TO THE ORIGINAL QUESTION??? :)

 

The speed of light is limited by the speed with which electric and magnetic fields spread outward from their soure.

[EWright]

The speed of light is limited by the speed with which electric and magnetic fields spread outward from their soure.

 

Then why call this the speed limit of the physical universe; one that can not be achieved by any physical thing? What qualitiy of space limits everything to this maximum speed? And what to do with EM fields causes gravity to assumably travel at this same speed?

[Bobby]

The speed of light is limited by the speed with which electric and magnetic fields spread outward from their soure.

 

 

Then why call this the speed limit of the physical universe; one that can not be achieved by any physical thing? What qualitiy of space limits everything to this maximum speed? And what to do with EM fields causes gravity to assumably travel at this same speed?

 

 

Personally, I don't see the speed of light as being any kind of speed limit. The speed of light is the speed with which electromagnetic energy propagates, and I don't know of any other kind of energy, but if such energy existed I see no reason to believe it would propagate at light speed.

 

There is a difference between a measured speed and the "real" speed. I think many people think that the "real" speed of light is the same everywhere, but this is not correct. If you run some kind of test, perhaps using the half life of a radioactive substance, you will get different results if the tests are run in different gravitational fields. You can then interpret the results as a difference it time.

 

I have heard people from Mexico being asked "Do you dream in Spanish or English?" I think this is an interesting question. I don't care what language they dream in, but it is an indication of what language they think in. To a certain extent, I think in mathematics. I don't know what "really" happens in different gravitational fields. I understand the mathematics and that seems to make sense to me, but it makes it very difficult to explain to a non-mathematical thinker.

[Southtown]

The speed of light is limited by the speed with which electric and magnetic fields spread outward from their sour[c]e.

Didn't Einstein say that the speed of light was the same regardless of source velocity. Not necessarily contradictory, just thinking out loud.

 

The speed of light is the speed with which electromagnetic energy propagates, and I don't know of any other kind of energy, but if such energy existed I see no reason to believe it would propagate at light speed.

 

There is a difference between a measured speed and the "real" speed. I think many people think that the "real" speed of light is the same everywhere, but this is not correct. If you run some kind of test, perhaps using the half life of a radioactive substance, you will get different results if the tests are run in different gravitational fields. You can then interpret the results as a difference it time.

Why time? Why not a difference in velocity? Isn't light made of matter? Wouldn't it be effected by gravition outside of a curved spacetime hypothesis?

 

To a certain extent, I think in mathematics. I don't know what "really" happens in different gravitational fields. I understand the mathematics and that seems to make sense to me, but it makes it very difficult to explain to a non-mathematical thinker.

This is a very good point. And it illustrates my difficulty in understanding cosmology (especially relativity.) I'm trying to learn the math (on my own,) but I simply can't accept it by itself since it's just a tool (or "language") for describing relationships of quantities. It explains the tangible things quite well, but undoubted extends far beyond that. Crescent wrenches can also work on cheese, but I don't know what one would expect to accomplish by utilizing them in that manner.

[CraigD]

Then why call this [the speed of light] the speed limit of the physical universe; one that can not be achieved by any physical thing? What qualitiy of space limits everything to this maximum speed?

The Theory of Relativity clearly states that accelerating any physical object (that is, any object with non-zero mass) to the speed of light requires an infinite expenditure of energy. For this reason, it’s reasonable to call the speed of light “the universal speed limit”.

 

There’s nothing intrinsic in the geometric definition of any particular space that requires such a speed limit to exist. For most of history, no such limit was thought to exist, and the speed of light was of no greater universal significance than the speed of a projectile fired from a particular cannon, the speed of sound in a gas of a particular density, or a wave traveling along a particular stretched string.

 

In 1887, the “failure” of the Michelson-Morley experiment showed that light is not like a cannonball, a sound wave, or the transverse wave in a stretched string. Once this was observed, the Lorentz transformation, Relativity, and the unusual significance of the speed of light had to follow.

 

It’s worth noting that not everybody accepts the results of the Michelson-Morley experiment. At the time it was done, and to this day, some argue that an unexplained “space dragging” effect is responsible for the measured observer motion-invariance of the speed of light. If this is the case, then the Lorentz transformation and Relativity don’t apply to this universe, and there’s nothing special about the speed of light. Many experiments unrelated to MM, especially direct measurement of relativistic time dilation, make such an overturning of the last century of physics seem very unlikely, IMHO.

[EWright]

The Theory of Relativity clearly states that accelerating any physical object (that is, any object with non-zero mass) to the speed of light requires an infinite expenditure of energy. For this reason, it’s reasonable to call the speed of light “the universal speed limit”.[/Quote]

 

Hence, because Einstein says so.

 

There’s nothing intrinsic in the geometric definition of any particular space that requires such a speed limit to exist.[/Quote]

 

Hence, must be because Einstein says so and because he was able to create the math to support it by 'zeroing out' everything at light speed.

 

In 1887, the “failure” of the Michelson-Morley experiment showed that light is not like a cannonball, a sound wave, or the transverse wave in a stretched string. Once this was observed, the Lorentz transformation, Relativity, and the unusual significance of the speed of light had to follow. [/Quote]

 

Yes, this is the beginning of understanding that the speed of light is always measured at the same rate. It has nothing to do with explaining why it would be the ultimate limit. By 'zeroing out' every measurement relative to light speed, of course it would be calculated that it would take an infinite amount of energy to get there. Is there an infinite amount of energy per photon?

[CraigD]

There are simply no physical properties of light that cause clocks of faster moving objects to run slower. Therefore, the notion of the speed of light as a determining factor as to why this happens is irrelevant and must be abandoned along with some other notions of special relativity.

Yes, there is.

 

If one accepts the postulate that a particular particle is observed by all observers to travel at the same velocity, then one must accept that a clock that uses these particles to measure the passage of time runs slower – measures less time having passed – when it is moving than when it is stationary, relative to a common reference point.

 

The reasoning for this is from simple geometry. It’s described in practically every introductory modern physics text, but since it’s very simple, I describe it in my own words here:

Postulate that a particle P exists and has the quality that it is always observed, by all observers, to move at the same velocity, Vp. Further, assume that this particle can be easily reflected – made to reverse direction – with no interruption in this constant (scalar) velocity, and similarly constrained to remain within a container made of 2 reflectors

 

Construct a clock consisting of 2 reflectors separated by a distance D such that P bounces between them, returning to the same position every 1 unit of time (tick).

 

Holding this clock, observer A moves at a speed of .75*vP in a direction perpendicular to the direction of movement of P in the clock, while observer B remains stationary.

 

After 1 tick measured by A, B observes that P has moved (D^2 + (.75*D)^2)^.5 (=1.25*D, the hypotenuse of a right triangle with base .75 and height 1)

 

Because, per postulate, P is always observed to move at the same speed, B has measured 1.25 ticks. A has measured 1 tick.

 

Therefore, A’s clock has run slower - measured less time - than B’s.

These described events can only occur in the actual universe if the postulated particle P actually exists. Mainstream Modern Physics affirms that such a particle, the photon, does exist.

 

Denying these described events necessitates denying that particle P, with the described attributes, actually exists – in the usual convention, denying that the speed of light is a independent of the speed of the thing – generator or reflector – that emits it.

 

Experimental evidence appears to be entirely in support of mainstream Modern Physics. A scientific rejection of it would require new experimental evidence contradicting all of the confirming evidence.

[Mr. Potato Head]

Can light travel in a circle? How would this affect the speed?

 

Where does light go when you remove the source? Why aren't there a bunch of photons lying on the ground? Or are they? Am I basically a bunch of photons?

 

Why can't we trap light between two mirrors after the source is removed? Or can we?

 

Can you look at the speed of light in a manner that suggests that time does not in fact stop at the speed of light, it only seems that way because if you were able to do work at the speed of light it would be done in "no time?"

 

If you were moving at the speed of light all around me, we both would still experience and be subject to time. Eventually, we would both die. Doesn't this indicate that time does not stop at the speed of light or at least indicate that there is no such thing as time in the natural world and only a measure created by us to ultimately know when our birthday is?

 

Who cares what our perception is? It isn't reality anyways. Remember that pretty much all I know about light is that I can see better when it's around. Be gentle if I am so far out of the blue that I am in the dark.

[EWright]

Postulate that a particle P exists and has the quality that it is always observed, by all observers, to move at the same velocity, Vp. Further, assume that this particle can be easily reflected – made to reverse direction – with no interruption in this constant (scalar) velocity, and similarly constrained to remain within a container made of 2 reflectors

 

Construct a clock consisting of 2 reflectors separated by a distance D such that P bounces between them, returning to the same position every 1 unit of time (tick).

 

Holding this clock, observer A moves at a speed of .75*vP in a direction perpendicular to the direction of movement of P in the clock, while observer B remains stationary.

 

After 1 tick measured by A, B observes that P has moved (D^2 + (.75*D)^2)^.5 (=1.25*D, the hypotenuse of a right triangle with base .75 and height 1)

 

Because, per postulate, P is always observed to move at the same speed, B has measured 1.25 ticks. A has measured 1 tick.

 

Therefore, A’s clock has run slower - measured less time - than B’s. [/Quote]

 

First of all, why can't physicists speak simple english? Secondly, while I agree that the two observers will measure time differently, you have not described a physical property of light or space that causes this to happen. Thus, you have not addressed the issue at hand. Thirdly, look up postulate or axiom in the dictionary and you'll find that they refer to an ASSUMPTION. And you know what you get when you ***-U-ME.

[Tormod]

First of all, why can't physicists speak simple english?

 

EWright - you are overstepping our rules here. If you cannot accept the replies you get, there is no need for ridicule. This is a science forum, you should not be upset by getting scientific replies.

 

Secondly, while I agree that the two observers will measure time differently, you have not described a physical property of light or space that causes this to happen.

 

Minkowski space-time has been supplied. Have you studied it so you know whether it is an acceptable reply or not?

 

Thus, you have not addressed the issue at hand.

 

Yes, he has.

 

Thirdly, look up postulate or axiom in the dictionary and you'll find that they refer to an ASSUMPTION. And you know what you get when you ***-U-ME.

 

Science is the art of assumption, and then turning that assumption into theory. You seem to have a deep disagreement with the scientific method, so why not come into the open with your own theory? If it is not ready for the light of day maybe you should put more work into in rather than waste your time here..

[EWright]

My apologies Tormod, allow me to rephrase.

 

Postulate that a particle P exists and has the quality that it is always observed, by all observers, to move at the same velocity, Vp. Further, assume that this particle can be easily reflected – made to reverse direction – with no interruption in this constant (scalar) velocity, and similarly constrained to remain within a container made of 2 reflectors

 

Construct a clock consisting of 2 reflectors separated by a distance D such that P bounces between them, returning to the same position every 1 unit of time (tick).

 

Holding this clock, observer A moves at a speed of .75*vP in a direction perpendicular to the direction of movement of P in the clock, while observer B remains stationary.

 

After 1 tick measured by A, B observes that P has moved (D^2 + (.75*D)^2)^.5 (=1.25*D, the hypotenuse of a right triangle with base .75 and height 1)

 

Because, per postulate, P is always observed to move at the same speed, B has measured 1.25 ticks. A has measured 1 tick.

 

Therefore, A’s clock has run slower - measured less time - than B’s.

[/Quote]

 

It is somewhat difficult to understand exactly what you are saying. If you state things more simply it would be helpful in making sure we're avoiding any miscommunication.

 

I do agree with you that both observers will measure time differently. I was not making any argument contrary to this. My position is that there are no physical properties of light that actually cause this to happen. For example, time will still be measured differently by two 'observers' if the experiment is conducted deep underground with no light available. (let's say they wear watches and compare later, since there's no light to 'observe' by at the time). Hence, again, it is not a property of light that is responsible for this phenomena. The same thing would happen if there was no light in the universe, and thus we did not have light speed to account for the phenomena.

 

As for agreeing with the posulates of SR, postulates are assumptions by deffinition. You stated that *IF* you accept this postulate, then the argument holds true. I do not disagree with this statement. But I have trouble agreeing with a posulate that grants light universal authority, when it is not a universal quantitiy. Light speed is a product of the physics of the universe we live in, not a dictator if its physics.

 

Tormod, you are right. I should work on furthering my own theory. It does account for the define the physical elements of the universe that account for light speed. I look for answers here because I am open to and welcome challenge to my ideas. But because I am not prepared to discuss them yet, I try to challenge them indirectly, but challenging those ideas of relativity that I take issue with. I am looking for answers acceptable enough to cast down on my own ideas. I am not a physicist or mathemetician, so in a way this is as close I can come to trying to 'disprove' my own ideas (for now). But I do not see how the statements I have made can be shown to be false. I will read up on Minkowski space-time so that we can be sure we're on the same page in future discussion.

 

Until then,

 

EW

[Southtown]

Therefore, A’s clock has run slower - measured less time - than B’s.

Time is not defined by clocks, though. Observer A's clock would be “discalibrated” by the addition of perpendicular (y) distance to the oscillating path (x) of the particle. The particle's path changes from lateral oscillation to a zigzag, therefore the actual distance from reflector to reflector changes when the clock starts moving, hence a slower oscillation.

[Bobby]

Didn't Einstein say that the speed of light was the same regardless of source velocity. Not necessarily contradictory, just thinking out loud.

 

 

Why time? Why not a difference in velocity? Isn't light made of matter? Wouldn't it be effected by gravition outside of a curved spacetime hypothesis?

 

 

This is a very good point. And it illustrates my difficulty in understanding cosmology (especially relativity.) I'm trying to learn the math (on my own,) but I simply can't accept it by itself since it's just a tool (or "language") for describing relationships of quantities. It explains the tangible things quite well, but undoubted extends far beyond that. Crescent wrenches can also work on cheese, but I don't know what one would expect to accomplish by utilizing them in that manner.

 

Well, I wasn't around when Einstein did most of his work. I doubt that he said the speed of light was the same everywhere, I suspect he said the speed of light would be measured as the same everywhere.

 

 

Why time? Why not a difference in velocity? Isn't light made of matter? Wouldn't it be effected by gravition outside of a curved spacetime hypothesis?

 

 

Velocity is a change in distance divided by the change in time, so a change in either time or distance will result in a change in velocity. Depending on how you want to look at it, light is either an electromagnertic wave or a photon. As you may know, an electric field can enduce a magnetic field and a magnetic field can enduce an elecric field. Light, and all electromagnetic waves, are an electric field and a magnetic field, each enducing the other as the wave moves along. A photon is also this wave, but the energy of the wave is such that the photon acts more like a physical particle than a wave.

 

Saying that spacetime is curved, or warped, gives the impression that spacetime is a real, physical entity. I don't think space and time are THINGS, rather they are MEASUREMENTS

made clocks and rulers. If there is anything resembling a real, physical entity, it would be the gravitational fields accociated with mass.

 

 

This is a very good point. And it illustrates my difficulty in understanding cosmology (especially relativity.) I'm trying to learn the math (on my own,) but I simply can't accept it by itself since it's just a tool (or "language") for describing relationships of quantities. It explains the tangible things quite well, but undoubted extends far beyond that. Crescent wrenches can also work on cheese, but I don't know what one would expect to accomplish by utilizing them in that manner.

 

Actually, the math to get a basis understand of relativity is only high school algebra and a little bit of geometry. If you want to get beyond this into Einstein's field equations, be prepared to spend the next several years learning the math.

 

 

Electromagnetic energy is the result of a vibrating electric charge. I can make a pretty good argument that our Universe is nothing more than electric charge with the added characteristics of mass. And, if our Universe is nothing more that electric charge and mass, then our Universe is PROBABLY a Black Hole in some mother Universe.