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Is this anything?

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(Grant me the idea of being motionless)

Am I describing anything here:

1. you are standing at a fixed point in space (lets say at the point where the big bang took place);

2. Things are moving away from you at increasing speed as they get further away;

3. at some point things are moving at the speed of light;

4. from where you are standing those light speed things are invisible;

5. even if you were to travel to the edge of this area those objects that are moving at the speed of light would still be invisible.

Is all, or any part, of the above desciptive of anything?

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Sounds like about a dozen beers, a few shots of tequila, some ether, and half a joint.

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There are no fixed points in space, just points at given distances from an object.

No observer will ever measure a material object as travelling at the speed of light, so there is no meaning to describing what it would look like.

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Re: Is this anything?

john/nyc wrote:

(Grant me the idea of being motionless)

Am I describing anything here:

1. you are standing at a fixed point in space (lets say at the point where the big bang took place);

You *are* at the center of the Big Bang. Every point in space is the center.

john/nyc wrote:

2. Things are moving away from you at increasing speed as they get further away;

Correct, and as a result, they are being red-shifted into obscurity.

john/nyc wrote:

3. at some point things are moving at the speed of light;

I don't know about this. Nothing (with mass) can move at the speed of light, but at some point, the relative acceleration should make it *appear* that an object has exceeded light speed and if so, it would definitely vanish from our view (since any light it emits would never reach us). Maybe Brandon can clarify this for me because I'm not sure how this would work.

john/nyc wrote:

4. from where you are standing those light speed things are invisible;

I would think so.

john/nyc wrote:

5. even if you were to travel to the edge of this area those objects that are moving at the speed of light would still be invisible.

Well, remember, nothing can actually move at the speed of light. But the question in my mind is whether it's *apparent* motion relative to us due to expansion might make it invisible.

john/nyc wrote:

Is all, or any part, of the above desciptive of anything?

It sounds a lot like Olbers Paradox.

The generally accepted solution to Olbers Paradox is that Red-Shift and the Young Age of the Universe prevent us from seeing a completely star filled sky.

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Actually the solution to Olbers' Paradox is found in the fact that while light travels a very long way in a near vacuum, it does not travel 'infinitely', eventually the light energy degrades to the point where it ceases to exist; beyond that point the source, regardless of the 'space/time' frame, is invisible. So in an infinite universe, which is what i believe we live in, the most distant objects (not even approaching infinity!) are obscured to us.

As has been pointed out, no matter where you set up your 'observing location' there will be light coming to you from objects radiating light in all directions within your field of view; while they will have an apparent speed relative to your position, they will not be travelling at the speed of light, in fact, relative to themselves, they will be 'motionless'!

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Re: Is this anything?

rosborne979 wrote:

I don't know about this. Nothing (with mass) can move at the speed of light, but at some point, the relative acceleration should make it *appear* that an object has exceeded light speed and if so, it would definitely vanish from our view (since any light it emits would never reach us). Maybe Brandon can clarify this for me because I'm not sure how this would work.

No material object will be observed travelling at the speed of light. No material object will "appear" to be travelling at the speed of light. You can't get around it.

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Re: Is this anything?

Brandon9000 wrote:

rosborne979 wrote:
I don't know about this. Nothing (with mass) can move at the speed of light, but at some point, the relative acceleration should make it *appear* that an object has exceeded light speed and if so, it would definitely vanish from our view (since any light it emits would never reach us). Maybe Brandon can clarify this for me because I'm not sure how this would work.

No material object will be observed travelling at the speed of light. No material object will "appear" to be travelling at the speed of light. You can't get around it.

Is that because it can't be seen or because it can not happen?

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Re: Is this anything?

john/nyc wrote:

Is that because it can't be seen or because it can not happen?

Because it cannot happen. To accelerate any matter, even something as small as one electron, up to the speed of light would require an infinite amount of energy.

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Re: Is this anything?

Brandon9000 wrote:

rosborne979 wrote:
I don't know about this. Nothing (with mass) can move at the speed of light, but at some point, the relative acceleration should make it *appear* that an object has exceeded light speed and if so, it would definitely vanish from our view (since any light it emits would never reach us). Maybe Brandon can clarify this for me because I'm not sure how this would work.

No material object will be observed travelling at the speed of light.

Hi Brandon,

Yeh, I know that. You're missing the point of my question.

I'm not asking this very clearly... let me try again...

Question: Is there a distance at which, things are accelerating away from us so quickly that the light emited from the objects will never reach us because the expansion exceeds light speed.

Maybe that's better. Do you see what I'm getting at here?

Thx,

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Re: Is this anything?

Brandon9000 wrote:

john/nyc wrote:
Is that because it can't be seen or because it can not happen?

Because it cannot happen. To accelerate any matter, even something as small as one electron, up to the speed of light would require an infinite amount of energy.

Not quite; photons of light, which can phenomenize as mass or energy, being 'light', travel at the 'speed of light'! (as do all electromagnetic phenomena).

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Re: Is this anything?

BoGoWo wrote:

Brandon9000 wrote:
john/nyc wrote:
Is that because it can't be seen or because it can not happen?

Because it cannot happen. To accelerate any matter, even something as small as one electron, up to the speed of light would require an infinite amount of energy.

Not quite; photons of light, which can phenomenize as mass or energy, being 'light', travel at the 'speed of light'! (as do all electromagnetic phenomena).

Correct, but I think Brandon was correct also. Brandon's post implied acceleration of mass, and his statement was correct. You are talking about massless things existing at the speed of light.

Photons are considered massless, and they do not *accelerate* to the speed of light, they *exist* at the speed of light. Such is the structure of space/time that all massless things exist at the speed of light.

This is easy to picture ... If something has zero mass, then even the tiniest bit of force applied to it will acclerate it instantly to an infinite velocity (based on the F=MA equation where M=0), and the infinite velocity is the speed of light.

In reality, things with zero mass never start with zero velocity, they come into existance with infinite velocity, just as it is a function of masslessness to exist at infinite velocity.

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Re: Is this anything?

BoGoWo wrote:

Brandon9000 wrote:
john/nyc wrote:
Is that because it can't be seen or because it can not happen?

Because it cannot happen. To accelerate any matter, even something as small as one electron, up to the speed of light would require an infinite amount of energy.

Not quite; photons of light, which can phenomenize as mass or energy, being 'light', travel at the 'speed of light'! (as do all electromagnetic phenomena).

Yes, quite. I very carefully stipulated that I was referring only to matter, and my statement is correct as it stands. No material object can be accelerated to the speed of light.

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only light travels at the speed of light. Planets and stars and galaxies do not move at the speed of light. Therefore, the answer to your question is no.

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Does anyone have an answer to Rosborne979's question as to two masses traveling away from each other (opposite directions) each at more-than-half the speed of light? Would these masses be invisible to each other?

Also, I read that there is theory which says that light eventually dies; that light sort of peters out. This, if so, would mean that a luminous mass at suffcient distance from the observer would be invisible. Any thoughts, corrections or comments?

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john/nyc wrote:

Does anyone have an answer to Rosborne979's question as to two masses traveling away from each other (opposite directions) each at more-than-half the speed of light? Would these masses be invisible to each other?

Any radiation, such as light, coming from one would be Doppler shifted towards longer wavelengths from the point of view of the other. Probably visible light would be shifted into a non-visible part of the spectrum. If the radiation coming from each could be detected at their distance without the relative speed, it could still be detected with the speed, just in a different part of the spectrum.

john/nyc wrote:

Also, I read that there is theory which says that light eventually dies; that light sort of peters out. This, if so, would mean that a luminous mass at suffcient distance from the observer would be invisible. Any thoughts, corrections or comments?

We know that objects appear smaller and dimmer the farther away they are moved from an observer. Of course in addition to the distance, another factor is the brightness of the object.

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john/nyc wrote:

Does anyone have an answer to Rosborne979's question as to two masses traveling away from each other (opposite directions) each at more-than-half the speed of light? Would these masses be invisible to each other?

Also, I read that there is theory which says that light eventually dies; that light sort of peters out. This, if so, would mean that a luminous mass at suffcient distance from the observer would be invisible. Any thoughts, corrections or comments?

John, the questions you are asking are answered by "special relativity". This branch of physics is accessible to anyone with a grasp of algebra and the ability to do a bit of intellectual work. This is usually taught the the third semester of Physics.

To understand it you need to work through the math with an example. The usual example involves trains, flashes of light and observers. This site looks like a typically good one.

http://theory.uwinnipeg.ca/mod_tech/node133.html

The answer to you question is that these masses would not be invisible to each other since one mass would not observe the other as going the speed of light. The math you are doing (adding the to velocities) is not correct under relativity.

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john/nyc wrote:

Does anyone have an answer to Rosborne979's question as to two masses traveling away from each other (opposite directions) each at more-than-half the speed of light? Would these masses be invisible to each other?

Hi John,

I looked up the answer to get a better explanation of exactly *why* this works the way it does.

The reason is that Einstein's theory does not limit the speed of space expansion--only motion through it. Objects in the Universe are expanding away from each other at 1.8 times the speed of light, but this does not break the light speed barrier since the distance is increasing due to expansion *of* space, and not velocity *through* space.

The best way to picture this is that while the space between objects is increasing, the light traveling between those objects is being stretched (red shifted) while it travels.

The link above describes this in more detail.

It was a good question. Thanks Smile

Smile

Best Regards,

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ROSBORNE & EBROWN,

Thanks !

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