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Moontanman

Registered: May 03
Posts: 81

quote:
Originally posted by LaBum
its been shown recently that light has mass (which is why it gets stoped when it hits somthing)

Light has rest mass, different thing from regular mass

and still can travel at the speed of light. Any ideas of being unable to travel faster than the sol has to do with an argument that if time stops how are you supposed to measure speed because speed is a measurement of distance over time..

Time doesn't stop except for one of two or more observers, for you it keeps right on ticking.

The ideas that the amount if gravity somthing has is been confused for momentum.
Does a 1 pound weight weigh more when going 60 mph?

Yes, not much but definutely yes.

Does it take siginifantly more ammounts of energy to go faster in a car(and how much if it is related to increased friction)?

Most of it is due to friction, aditional mass only becomes significant near light speed

There has been some thought that going faster than light could propel Mass into the past. So imagine gettting on a ship to go to a star and arriving before you left.

Nope doesn't work like that, time slows down as you approch the speed of light for an observer but for you it stays the same. Same thing for theroreticly exceding the speed of light. The backwards time only works for the static observer for you everything is still the same.

Moontanman
a little knowlege is a dangerous thing
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Moon

08/14/03 06:05

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Coppernicus2

Registered: Jun 03
Posts: 158

Radrook,

I'm still puzzling over this "no faster than light" concept, with which I am not in disagreement, only uncomfortable that we are doing it justice. You wrote (8/5/03):

"What I disagree with is when someone says that if two objects were approaching each
other at c then they have both broken the speed of light. Or that in order to avoid that
they break the speed of light we have to assume that they total speeds are below what
simple addition of velocities tell us. Obviously each ship individually is NOT going beyond
the speed of light. So Einstein's equation is NOT being violated."

Now, on the surface, this seems right. But if you think of it further, say a light bulb giving off photons in opposite directions, then what is the velocity of these photons versus the 'stationary' light bulb? It is v = c, of course. But what is the velocity of these photons versus each other?

So you see, now we have a problem. Either we disregard space and call all motion relative to the source only, then v = c, always. But if we disregard the source, since once the photon leaves the source it is independent of it, then v > c, or even v = 2c. This is my dilemma: what do we use as a velocity reference in space? If there is no aether, then any velocity measured against another, especially if they are either moving away from each other vectorially, or towards each other, then in relation to each other, they can be going at twice lightspeed. Hmmm... Any way out of this dilemma?

I remain puzzled, but not convinced of my own argument. This does not negate the idea that two cars traveling at each other at 80 mph are each still only doing 80 mph, not 160 mph. However, in relation to space, once they pass each other (no collision), then they are traveling away from each at 160 mph in relation to each other, though both cars are only doing 80 mph in relation to the road traveled.

If so, then anything could be at v = c, or =2c, in space! Therefore, in relation to each other, photons or electrons traveling away from each other at v = c can have a relative speed of v = 2c. Hence my dilemma.

C2
__________________
I have formally 'resigned' (tactical withdraw) from the Space-Talk boards; mine were many questions, ideas, but no real answers. Thanks. 04/10/04.

Disclaimer: Please note the ideas expressed here by me are cutting edge theory, very speculative in nature, and not physics as it is being currently taught. Caveat lector.

08/21/03 04:05

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wintermute11

Registered: Mar 03
Posts: 485

quote:
What I fail to see is how if I run at 15 mph in one direction and you run at 15 mph in the opposite direction that this means that I am actually running at 30 mph. Obviously no human has the ability to run at that speed.

You're right. Nobody could run that fast relative to the ground. That is 30 mph relative to the other runner. Another way to understand it is put that runner on a moving walk way (like you see at some airports) moving 15 mph in the same direction as the runner. To the walk way or somebody standing on the walk way, the runner is still running 15 mph. To a stationary observer not standing on the moving walk way that runner is indeed moving at 30 mph relative to them.

quote:
Conversely, if two photons move away from one another, each traveling at 186,000 mps, how can it be said that they have both violated the speed of light barrier when each one individually is incapable of doing so?

You are absolutely right. That was the problem before Einstein proposed special relativity. Without the effects of special relativity, you are absolutely right. That should not be possible. However, it is. Time dilation allows this to be true.

quote:
If I run at 15 mps away from a stationary person, it becomes clear that I am unable to run at 30 mph.

Again, you are absolutely right. But your first example was 30 mph relative to the other runner, not a stationary observer.

quote:
If one of the photons were stationary, then the other obviously is NOT going faster than what it is capable of.

Photons not only travel the speed of light, but they can ONLY travel the speed of light. They do not stop. They have no rest mass. They do have momentum, just no rest mass.

I know that some people will attempt to quote experiments where photons were stopped. These were captured, not stopped. Atoms can capture a photon. All the energy contained within the photon is transferred to an electron raising it to an excited state. Energy is conserved. This is an effect that we see all the time. The difference is that in these experiments, the electron does not fall back down to a lower state emitting a photon in the process. It remains in the excited state until a condition is met, in which it falls back down, emitting the photon. The energy lost by the electron is emitted as a photon (quantum) having the same energy that was lost by the electron. Energy is conserved.

Those more learned will note that light slows down in a medium other than a vacuum. As the index of refraction of the transmission medium increases, the velocity decreases. This is a net velocity, but the light still actually travels at 186,000 mps. Its just captured by many atoms along the way, delaying propogation.

08/21/03 16:13

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wintermute11

Registered: Mar 03
Posts: 485

To anybody reading these messages, most of what Radook said is wrong. Do your own research. Open a physics text book and read for yourself. That which is worth correcting, I already explained in my previous message.

The only other correction that needs to be made is

quote:
On the other hand, if mass is the problem in accelerating past the speed of light and you claim that photons don't have mass, then photons should be able to exceed the speed of light without any trouble at all. So there is a contradiction here.

Thats why we qualify it with REST mass. There is a difference. Light has no REST mass.

08/21/03 22:59

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Coppernicus2

Registered: Jun 03
Posts: 158

Radrook, wintermute11,

Yes, I suspect we are "hardwired" to see things a certain way, which is why Relativity seems odd, though the system is consistent, even proven.

Indeed all things are relative. My velocity in terms of myself, sitting at this computer, is zero. In relation to my local star, it is rather high; and in relation to the galaxy center, my velocity is quite enormous. But what does this mean in relation to space itself? If my velocity, which is zero for me, is taken in relation to the edges of the visible universe, then I am traveling at nearly light speed. I don't feel any different, nor is my mass expand (unless I've had too much to eat!), so conceptually, at least, I must conclude that reality is already "relativistic". This means that what is real is what you get, and thus all Relativity concepts are merely our way to try to understand the universe from some other point of view, that of a very high velocity observer, rather than our own.

That we keep recreating the "road" on which we are running is akin to recreating the "aether" within which light travels. As you point out, running at 15 mph does not mean you are ever really running at 30 mphs relative to the road, though in terms of space devoid of a "road/aether", this could be that you are running at 30 mph, since there is no stable, fixed reference from which to measure velocity, unless one is chosen. The point being, that we live in a "relativistic" universe, for which we had developed relativistic concepts, but these are observational concepts only, and not the real thing. In effect, reality does not bear out Relativity, other than hypothetically. Newtonian physics serves us rather well, even if we are already traveling at near light speed, so that the mathematical interpretation of time dilation or mass expansion are not real, though proven. Nor may they be necessary in the real world. At least, that is how it appears to be, though maybe I'm wrongly "hardwired"!

Regarding light traveling through a medium at below light speed, you are most correct, a very astute observation, that the velocity never slows down, only the net effect is slower since it must pass through all those atoms in the way.

Thanks for helping out with this dilemma, which still leaves me scratching my head. This is becoming a philosophical question: Can I possibly be traveling at 186,000 mps in relation to (not a road or aether) the space of the reality of the universe, while I perceive myself as traveling a velocity of zero? Is this not a paradox? Do I need Relativity to solve this, or is it merely that the universe already does all this for us? The result is what we see here. Can you see what I'm getting at? How useful is relativity?

C2
__________________
I have formally 'resigned' (tactical withdraw) from the Space-Talk boards; mine were many questions, ideas, but no real answers. Thanks. 04/10/04.

Disclaimer: Please note the ideas expressed here by me are cutting edge theory, very speculative in nature, and not physics as it is being currently taught. Caveat lector.

08/22/03 00:44

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JoeC

Registered: Jul 03
Posts: 54

quote:
Originally posted by Radrook
There is no law prohibiting light from traveling at less than the speed of light.

Yes, there is. That massless particles always travel at c is a basic tenent of Special Relativity. Special Relativity is as close to a "law" as science gets these days.

quote:
Originally posted by Radrook

I KNOW that light has rest mass.

It does not.

quote:
Originally posted by Radrook

EVERYTHING has rest mass. [before you accuse me of using the term wrongly--I am using it loosely]

Loosely or not, it's an incorrect statement. Photons do not have rest mass.

quote:
Originally posted by Radrook
But once mass is accelerated, it becomes more massive, something that is common knowledge but which you were denying vehemently and saying that it was simply relativistic until Andy set you straight.

The fact of the matter is, the increase in mass is "relativistic". Observers in different reference frames will observe the mass of your traveler to be different.

I couldn't find the specific posts you're referring to, but I'm sure you misunderstood Wintermute. Most likely, he was trying to correct a false notion you had as recently as last week. Namely, implying that there was a possibility of travelers at relativistic speeds experiencing negative effects due to increased mass.

I'm just an armchair relativity student, but it's clear to me that Wintermute knows what he's talking about. He knows much more about Relativity than I do, and much, much more than you do.

In addition to the quotes above, when you say things like this:

"What I disagree with is when someone says that if two objects were approaching each other at c then they have both broken the speed of light. Or that in order to avoid that they break the speed of light we have to assume that they total speeds are below what simple addition of velocities tell us."

It shows you're lacking some of basic concepts of Special Relativity. You got the first part right (somehow), but the total speeds are below what simple addition tells you. There's a formula in Special Relativity for computing relative speeds: relative speed = (v1 - v2)/(1 + v1*v2/c^2)

Again, it's a basic tenet of Special Relativity. Plug numbers into it. See what happens. Learn.

Wintermute, feel free to correct me if I messed something up here.

08/22/03 03:16

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JoeC

Registered: Jul 03
Posts: 54

Coppernicus2, there are many, many things that are incorrect in your last post. However, the problem can be summed up in one quote:

quote:
Originally posted by Coppernicus2
This is becoming a philosophical question: Can I possibly be traveling at 186,000 mps in relation to (not a road or aether) the space of the reality of the universe, while I perceive myself as traveling a velocity of zero? Is this not a paradox?

Radrook, you should pay attention because you're making the same mistake, even though you don't realize it.

No it's not a paradox.

"the space of the reality of the universe" as a reference frame in relativity does not exist. What you're doing (and perhaps not realizing it) is trying to create a special reference frame in which you can determine your "real" velocity (or your "real" mass, for that matter). The very core of relativity is that this concept is incorrect.

Your velocity (or mass) truly is relative.

quote:
Can you see what I'm getting at? How useful is relativity?

It's very, very useful.

Edit: Not sure if this helps, but if you like, you can consider your "real" mass to be whatever you measure it to be. Because no matter where you go or how fast you get there, it'll always measure the same to you.

08/22/03 03:41

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Coppernicus2

Registered: Jun 03
Posts: 158

JoeC,

You say: "Coppernicus2, there are many, many things that are incorrect in your last post. However, the problem can be summed up in one quote..."

In the above, I think my reasoning is rather straightforward. Could you give me a short answer as to why you think my reasoning is incorrect? After all, why should I believe you? If "Your velocity (or mass) truly is relative", then I must ask: is relative to what?

You say: "It's (Relativity) is very, very useful."

Useful to whom? Other Relativists? Why is it totally ignored in the engineering of the space program? Could it be a fantastic tale believed only by its true believers? If you say it is all relative to v = c, then it proves my point. We are already traveling at near light speed in relation to some part of the universe, and yet our time is not dilating, nor is our mass increasing. So... how useful is that?

C2
__________________
I have formally 'resigned' (tactical withdraw) from the Space-Talk boards; mine were many questions, ideas, but no real answers. Thanks. 04/10/04.

Disclaimer: Please note the ideas expressed here by me are cutting edge theory, very speculative in nature, and not physics as it is being currently taught. Caveat lector.

08/22/03 05:43

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wintermute11

Registered: Mar 03
Posts: 485

Radrook, please don't misquote me

quote:
I KNOW that light has rest mass...

Winetermute is wrong in saying that photons have rest mass.

Read my posts a little more carefully. I said photons have no rest mass.

Yet another accidental misspelling of my name?

quote:
The old definition of mass, called "relativistic mass," assigns a mass to a particle proportional to its total energy E, and involved the speed of light, c, in the proportionality constant:

m=E /c2.

Actually, what we are referring to by relativistic mass is that which is predicted by the Lorentz Transformations, and observed experimentally.

08/22/03 16:33

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JoeC

Registered: Jul 03
Posts: 54

quote:
Originally posted by Radrook
Excerpt:
A limit on the photon mass can be obtained through satellite measurements of planetary magnetic fields. The Charge Composition Explorer spacecraft was used to derive a limit of 6x10-16 eV with high certainty. This was slightly improved in 1998 by Roderic Lakes in a laborartory experiment which looked for anomalous forces on a Cavendish balance. The new limit is 7x10-17 eV. Studies of galactic magnetic fields suggest a much better limit of less than 3x10-27 eV but there is some doubt about the validity of this method.

What you are quoting here, are the results of experiments that are attempting to put an (experimental) limit on the rest mass of a photon.

As the experiments become more accurate, limit of the rest mass of a photon will get smaller and smaller. It will in fact approach zero, experimentally. They will never experimentally prove that a photon has no rest mass because they will never be able to stop one to measure it (since it must travel at c�another tenet of Special Relativity you choose not to learn about).

Here are two more quotes from the same article:

"If the rest mass of the photon was non-zero, the theory of quantum electrodynamics would be 'in trouble'".

And:

"A non-zero rest mass would lead to a change in the inverse square Coulomb law of electrostatic forces"

And finally, the first sentence (which you conveniently left out) from your quote above is:

"[If photons have mass] the behavior of static magnetic fields is likewise modified."

So essentially, if a photon has mass, we need to throw out the rules about static magnetic fields, Coulomb's Law and the theory of quantum electrodynamics. In addition, Special Relativity falls apart.

Are you prepared to argue that all of the notions listed above, with mountains of experimental evidence in their favor, are wrong? That's what you will need to do.

quote:
Originally posted by Radrook
First, yes you did miss something here.
You missed the very clear fact that it was Wintermute who said that light has rest mass--I was merely following his assumption

No he did not. Please quote him saying that photons have rest mass.

quote:
Originally posted by Radrook
not based on my misunderstanding of his statement, but based on the fact that I had read previously that photons can be viewed under particle physics as having a rest mass.

No, they can not be viewed under particle physics as having a rest mass. Please post a source.

quote:
Originally posted by Radrook
Instead of accusing me of misunderstanding Wintermute, you should instead be saying that Winetermute is wrong in saying that photons have rest mass.

Here's precisely what Wintermute said just yesterday:

"Thats why we qualify it with REST mass. There is a difference. Light has no REST mass."

You, Radrook, repsonded by saying this:

"I KNOW that light has rest mass.
But its velocity should make it MORE massive not less.
EVERYTHING has rest mass. [before you accuse me of using the term wrongly--I am using it loosely]"

I'm not sure how much more clear it gets. Wintermute spoke correctly. You spoke incorrectly.

quote:
Originally posted by Radrook
The fact that you claim that my mathematics is off simply shows that you are one of those individuals who condemns without examination and approves the impossible based on the mere flaunting of supposed credentials alone.

First of all, I stated my "supposed credentials" right away. I essentially said that I am somewhat less clueless than you.

Second, your mathematics were off. You cannot just add velocities in relativity the way you do in Newtonian physics. It's really that simple.

Thirdly, it's not condemning without examination. Special Relativity is an accepted explanation that has been tested time and time again and has passed with flying colors.

You're making the mistake of thinking you and I are having a debate here. If you're debating anyone, you're debating Einstein. I'm merely presenting to you the tenets of Special Relativity that have been proved out experimentally. If you don't believe them, go do your own experiments and attempt to disprove Special Relativity.

Good luck in that endeavor!

quote:
Originally posted by Radrook
As for the effects of transluminal velocities on the human organism due to mass increase, the only way to know for sure is via experimentation. What I claimed is that WE DO NOT KNOW F0R SURE.

First of all, "transluminal" would mean "faster than light". I'm pretty sure that's not what you meant.

Second, in order for someone (or thing) to feel some sort of effect from relativistic speeds requires that Special Relativity is wrong. It requires a concept of an object's "real" velocity. That concept does not exist in Relativity. Period. End of story.

quote:
Originally posted by Radrook
But since you seem to have a pipeline to God--I guess that you know already.

See, here's your problem. You're behaving in this thread as if there is something about Relativity that needs to be explained. There isn't. You just need to understand what is already there. The only pipeline that is needed is between you and a physics book.

quote:
Originally posted by Radrook
By the way, accusing me of making statements I never made is fallacious reasoning.

Please quote me accusing you of saying something you didn't say.

All I said is that you leave open the possibility of some physical effect on the traveler from traveling at relativistic speeds. You said it again just now ("WE DO NOT KNOW FOR SURE"). What you don't realize is that you are questioning the validity of Relativity. You are going to need to pack a lot of evidence if that's what you are trying to do. So far you have not provided one scrap.

quote:
Originally posted by Radrook
As foe Winter's vast incontestable knowledge, I have found him inaccurate on two counts already. First, on his assertion that the increase in mass at high velocities is an illusion.

You simply don't understand the concept of relativistic mass. I don't know what else to say.

quote:
Originally posted by Radrook
Second, on his assertion that gravity has infinite range and travels instantaneously.

Gravity does have infinite range. Here's the Newtonian formula for gravity:

Gravitational force = (G * m1 * m2) / (d^2)

Plug different numbers in for d and see what happens. Try and find a value for d such that gravitational force equals zero.

quote:
Originally posted by Radrook
Third, on his incapability to grasp that the concept of gravity is one under Einstein's physics and another under particle physics.

Gravity works the same in particle physics. I�m totally at a loss here.

quote:
Originally posted by Radrook

then at least refrain from going on an evangelistic campaign to convert others to your dubious religion.

I'm just stating facts, as best as I understand them, about the Theory of Relativity. You're making statements that challenge or question the correctness of relativity. So again, you're not arguing with me...you're arguing with Einstein and thousands of physicists that use relativity in their everyday work.

quote:
Originally posted by Radrook
But learning by listening and accepting ridiculous concepts without thinking is not my style. Obviously it is yours, but to each his own.

Why not try learning about relativity before you try to poke holes in it? Relativity explains why the rest mass of a photon must be zero. Relativity explains why a massless particle must travel at c. Relativity explains why a traveler at relativistic velocities does not undergo some structural change that could be hazardous to him or her. Why not learn what relativity's explanations for these things are?

And I�m sure Einstein, Lorentz, et al would be quite amused that you think their concepts are �ridiculous�.

quote:
Originally posted by Radrook
It is when considering light as particles that the rest mass issue becomes relevant.

See again, there is no "issue". The "rest mass issue" is solved (ie: it's not an "issue"). It's solved by something called "Special Relativity". Again, it�s this simple: Either a photon has no mass or Einstein was wrong.

I don�t know what else to say. Pretty much every �question� or �theory� or �paradox� or �issue� you come up with is already explained by relativity. The problem is that you just don�t understand it. I guess ultimately what you want is for someone here, on Space Talk to prove the Theory of Relativity to you. I�m afraid that�s not going to happen.

08/22/03 19:29

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