double the speed of light

[apricimo]

If two objects are zooming past each other in opposite directions at the speed of light are their combined speeds not 2 x the speed of light? I mean forget transformation of coordinates and all that. Just thinking physically about two objects travelling past each other.

[ydoaPs]

If two objects are zooming past each other in opposite directions at the speed of light are their combined speeds not 2 x the speed of light? I mean forget transformation of coordinates and all that. Just thinking physically about two objects travelling past each other.

Velocities don't add like that.

[insane_alien]

a third observer who see's them travelling towards each other at equal velocities will indeed measure their relative velocity to be 2c.

 

HOWEVER, if you were to look from the point of view of one of the objects, the other object would be approaching very close to, but not quite at c.

[apricimo]

Velocities don't add like that.

 

Yes Thank you I realize that. That's why I said forget the (Lorentz) transformations and just intuitively think about it. No need to reply if you don't add anything in the end and just want to show you know more but then you don't even share that.

 

a third observer who see's them travelling towards each other at equal velocities will indeed measure their relative velocity to be 2c.

 

HOWEVER, if you were to look from the point of view of one of the objects, the other object would be approaching very close to, but not quite at c.

 

That's the part thats difficult to conceptualize. I'm just thinking in terms of seeing with my eyeballs. If I am in a spaceship and I am flying at the speed of light and the speed of light is 3 x 10^8 m/s then in order for me to SEE that spaceship the photons would have to be bouncing off the spaceship and then hitting my eyeball at 2c.

 

Or will my physiology be affected? i.e. I literally won't see the other spaceship?

[Fuzzwood]

The light will still be approaching at C. You will see the spaceship moving in a distance AND see it flying past you. This might be a bad example to quote some sci-fi, but what I think that happens is in Startrek TNG known as the Picard Maneuver.

Edited January 6, 2011 by Fuzzwood

[apricimo]

If two objects are zooming past each other in opposite directions at the speed of light are their combined speeds not 2 x the speed of light? I mean forget transformation of coordinates and all that. Just thinking physically about two objects travelling past each other.

 

Ok... Three observers...

 

One is standing still and the other two are zooming past each other in opposite directions at the speed of light respectively.

 

The standing still observer sees two ships traveling at at a combined speed of 2c.

 

Two questions. How can the standing still observer see the ships and how can the observers iside the ships see each other?

 

If a ship is already traveling at the speed of light then for you to see it a photon has to bounce off the ship and then into your eye. By the time the ship is seen it has already come and gone.

 

For the two guys inside the ship... They have come and gone twice as fast... Is that really it?

 

So the answer is you cannot see each other in "real time". There is some lag time by the time anyone sees anyone and that lag time will depend on the distance from each observer?

 

Did I answer my own questions?

[Janus]

Ok... Three observers...

 

One is standing still and the other two are zooming past each other in opposite directions at the speed of light respectively.

 

The standing still observer sees two ships traveling at at a combined speed of 2c.

 

Two questions. How can the standing still observer see the ships and how can the observers iside the ships see each other?

 

If a ship is already traveling at the speed of light then for you to see it a photon has to bounce off the ship and then into your eye. By the time the ship is seen it has already come and gone.

 

For the two guys inside the ship... They have come and gone twice as fast... Is that really it?

 

So the answer is you cannot see each other in "real time". There is some lag time by the time anyone sees anyone and that lag time will depend on the distance from each observer?

 

Did I answer my own questions?

 

First off, it is important to note that no material object or observer can travel at exactly the speed of light relative to another. So let's say that they are moving at 0.999999c, meaning that according to the first observer they have a closing speed of 1.999998c with respect to each other. For this observer, the light from each ship will arrive just a little bit ahead of the ship.

 

For an observer in either ship, the relative speed between ships will be 0.99999999999949999949999975c, and since the light from the other ship travels at c, it will arrive just the tiniest bit before the other ship does.

[manderson]

I agree with you 100%. The speed of light is not constant, but rather it is relative to the speed of the observer. If you are stationary, then the relative speed is 186k, but if you travel at 50% of this relative constant, then the relative speed of light slows down by 50% (meaning travel time increases proportionately, while distance travelled illusively APPEAR to increase proportionately). If you go at 100%, then the relative speed of light is 0 (meaning you are not moving relatively speaking, but in fact you do absolutely at 200% relative to a stationary reference).

 

What your beautiful question ask is what happens if you reverse directions. By doing so you can exceed the relative speed of light. I know they say this is impossible, but i do not believe this claim. I believe you can double the relative speed of light simply by travelling at the speed of light in the reverse direction (this is the 6th orthogonal dimension). When you do this time disappears! FYI: when you travel in positive direction at the speed of light, space stands still (but only SEEM to disappear...this apparition is an illusion because the speed of relative travel is 0 in the former case).

 

Now if you were to travel in the 5th dimension, the maximum you could increase the relative speed of light is 50% (total 150%), and from their you would diminish proportionately with duration/distance down toward 186k but never reaching it.

 

DISCLAIMER: everything is just wrote could be all B.S. i am not a physicist, i have zero training....but these are simply my thoughts. i welcome feedback (no posturing please...)

[ACG52]

I agree with you 100%. The speed of light is not constant, but rather it is relative to the speed of the observer. If you are stationary, then the relative speed is 186k, but if you travel at 50% of this relative constant, then the relative speed of light slows down by 50% (meaning travel time increases proportionately, while distance travelled illusively APPEAR to increase proportionately). If you go at 100%, then the relative speed of light is 0 (meaning you are not moving relatively speaking, but in fact you do absolutely at 200% relative to a stationary reference).

 

 

You don't often see something so completely incorrect.

 

(unless you hang around science forums)

 

The speed of light is the same for all observers regardless of their relative motion.

Edited January 17, 2013 by ACG52

[manderson]

ooh what misguided arrogance. read and regurgitate and believe that is intelligence. i can assure you time is NOT constant, and it does vary. this is what makes wormholes and time travel possible. co-founder of string theory (mikio kaku) agrees, but u the self-appointed genius critic presumably know better. the gentleman who posed the question about travellling at 2c is brilliant and i agree with him even if it turns out we are both wrong. u on the other hand lack imagination and mistake regurgitation for intelligence.

[elfmotat]

ooh what misguided arrogance. read and regurgitate and believe that is intelligence. i can assure you time is NOT constant, and it does vary. this is what makes wormholes and time travel possible. co-founder of string theory (mikio kaku) agrees, but u the self-appointed genius critic presumably know better. the gentleman who posed the question about travellling at 2c is brilliant and i agree with him even if it turns out we are both wrong. u on the other hand lack imagination and mistake regurgitation for intelligence.

 

Did you even read what he quoted, or were you just outright put-off by the fact that he bothered to disagree with your nonsense? The speed of light certainly isn't observer-dependent, as you claimed. This is the core assumption of relativity.

[manderson]

i trust the views of mikio kaku over your dogmatism (u sound like a religious fundamentalist - definately not using the scientific method). mikio kaku asserts that due to differences in the relative speed of light, time beats faster on the moon than on the earth, and even faster at your head than at your feet.

 

far from nonesense, what i say have support from hawkins & kaku: they believe the speed of light is relative and that einsteins constant ("c") refers to a ratio not an absolute speed. rather than self-aggrandizement maybe you should just google for few moments to see what both leading physicist have to say on the issue (try that instead of arrogance).

[CarbonCopy]

If two objects are zooming past each other in opposite directions at the speed of light are their combined speeds not 2 x the speed of light? I mean forget transformation of coordinates and all that. Just thinking physically about two objects travelling past each other.

 

This is exactly the reason why Einstein created Special Relativity, so that he could explain this. Oh, and you have to use Lorentz transformation for this, you can't think 'intuitively' at these speeds because our intuition does not work here. It works only for Newtonian Mechanics.

[swansont]

i trust the views of mikio kaku over your dogmatism (u sound like a religious fundamentalist - definately not using the scientific method). mikio kaku asserts that due to differences in the relative speed of light, time beats faster on the moon than on the earth, and even faster at your head than at your feet.

 

far from nonesense, what i say have support from hawkins & kaku: they believe the speed of light is relative and that einsteins constant ("c") refers to a ratio not an absolute speed. rather than self-aggrandizement maybe you should just google for few moments to see what both leading physicist have to say on the issue (try that instead of arrogance).

 

!

Moderator Note

 

Let's dial back the invective and discuss the science. OK?

 

If you have a source for your claim that Kaku thinks that speed of light is not constant in inertial frames you best find a link to it, because relativity predicts that time is not invariant, and that's based on c being the same in all inertial frames. It's doubtful that Kaku has said what you claim.

 

[ydoaPs]

Kaku does tend to say a lot of stupid things on TV so he can appear on TV, but I doubt even he would say something that wrong.

[manderson]

Moderator i agree. lets erase entirely the personal attack INITIATED against me by the gentleman (i am shocked at such a response and it caught me off guard: hence the rebuttles). please instead see the following links so this matter may be discussed rationally:

http://iopscience.iop.org/0264-9381/11/5/001/pdf/0264-9381_11_5_001.pdf (Alcubierre: The Warp Drive - Hyperfast travel within general relativity) - you need to purchase the article, however Alcubierre's equation is below:

 

EQUATION:

where

• is the lapse function that gives the interval of proper time between nearby hypersurfaces,
• is the shift vector that relates the spatial coordinate systems on different hypersurfaces, and
• is a positive definite metric on each of the hypersurfaces.

Alcubierre's Warp Drive essentially posits that you can exceed the relative constant inside wormholes by warping (contracting in front and expanding behind) space.

 

http://www.youtube.com/watch?v=iJZXDEUOao0 (kaku on Alcubierre)

 

(Hawking on wormhole time travel...ie exceeding speed of light)

 

(Kaku: Why your head is older than your feet)

 

My proposal (and reasoning) that APRICIMO's idea of doubling the speed of light is theoretically possible rest on the concept of wormholes. it is the idea that everything is porous (has holes) including time itself, thus enabling inter-dimensional travel. The theory of relativity breaks down immediately after the big bang and inside wormholes: alcubierre's equation allows e=mc2 to still hold because of warping.

 

The thought experiment i use is standing on a beam of light, parallel to a second beam travelling in same direction. in this thought experiment, from light's perspective LIGHT HAS NO SPEED. APRICIMO's idea would simply involve having the 2nd beam travel in the reverse direction to create warp. I would appreciate a reasoned rebuttle, rather than simply having my thoughts referred to as "nonsense" (that is what is invective).

Velocities don't add like that.

velocities should work like that under warp conditions. this requires imaging one is not on the surface of the universe, but rather travelling through holes in it. sort of like travelling through tiny holes in our planet to get to the other side, as opposed to travelling on the surface of our planet. now imagine our planet is the universe with similar wormholes that allow you to go from one side to the next. we do know that blackholes exist and it is believed wormholes exists, so i do not see his proposal as without merit. for us light speed appears to be fixed simply because we can only engage in positive time travel (currently). if each integer of time had a corresponding negative value (which i suspect it does), then the proposal makes sense.

Ok... Three observers...

One is standing still and the other two are zooming past each other in opposite directions at the speed of light respectively.

The standing still observer sees two ships traveling at at a combined speed of 2c.

Two questions. How can the standing still observer see the ships and how can the observers iside the ships see each other?

If a ship is already traveling at the speed of light then for you to see it a photon has to bounce off the ship and then into your eye. By the time the ship is seen it has already come and gone.

For the two guys inside the ship... They have come and gone twice as fast... Is that really it?

So the answer is you cannot see each other in "real time". There is some lag time by the time anyone sees anyone and that lag time will depend on the distance from each observer?

Did I answer my own questions?

the old saying: if a tree falls in the forest and you did not see it or hear it, did the tree actually fall. of course it did - the fact that you cannot see it has no bearing on the fact that it happened. likewise with light i suspect: our senses ability to detect should have no bearing on what absolutely (or relatively) happened.

Ok... Three observers...

One is standing still and the other two are zooming past each other in opposite directions at the speed of light respectively.

The standing still observer sees two ships traveling at at a combined speed of 2c.

Two questions. How can the standing still observer see the ships and how can the observers iside the ships see each other?

If a ship is already traveling at the speed of light then for you to see it a photon has to bounce off the ship and then into your eye. By the time the ship is seen it has already come and gone.

For the two guys inside the ship... They have come and gone twice as fast... Is that really it?

So the answer is you cannot see each other in "real time". There is some lag time by the time anyone sees anyone and that lag time will depend on the distance from each observer?

Did I answer my own questions?

another analogy: airplane flying at mach 2. u do not hear the sound of this airplane until after it has passed. the fact that you did not HEAR the sound of the airplane until AFTER it passed has no bearing on the fact that it was travelling at mach 2. our sensory capacities do not dictate reality, they only detect it....and if they are unable to detect it does not mean reality did not occur.

[swansont]

I would appreciate a reasoned rebuttle, rather than simply having my thoughts referred to as "nonsense" (that is what is invective).

!

Moderator Note

You need to start a new thread if you want to discuss warping and the Alcubierre drive; there is nothing in the OP that implies that we are discussing anything outside the realm of special relativity to answer the question.

 

Further, when you admit that "everything is just wrote could be all B.S." and invite feedback, you really shouldn't complain when you get corroboration. What you wrote in your first post, from the standpoint of SR, was egregiously wrong. i.e. nonsense. So please stop the posturing.

[ydoaPs]

Even in an Alcubierre drive, c is still constant and invariant. And velocities still don't add the Galilean way.

[SamBridge]

Even if you use wormholes you're still not "traveling" faster than light, in fact you're not traveling anywhere at all because a wormhole makes two 3-D coordinates overlap and become the same coordinate.

[manderson]

ok ok some clarity here. i did not say we can EXCEED the ABSOLUTE speed of light. what i spoke of was RELATIVE SPEED, which is what i think the post is about. I do not believe "c" is at all the speed of light, rather i believe light itself has no absolute speed and only appears to have speed. we could easily say light is stationary and it is our universe that is moving at "c", hence the ratio is the only thing that is absolute and not light itself.

 

Example: we are on spaceship earth. are we travelling at the speed of earth's movement through space or are distant objects in space approaching us? our 'movement' is relative (not absolute) - same with light.

[SamBridge]

ok ok some clarity here. i did not say we can EXCEED the ABSOLUTE speed of light. what i spoke of was RELATIVE SPEED, which is what i think the post is about. I do not believe "c" is at all the speed of light, rather i believe light itself has no absolute speed and only appears to have speed. we could easily say light is stationary and it is our universe that is moving at "c", hence the ratio is the only thing that is absolute and not light itself.

 

Example: we are on spaceship earth. are we travelling at the speed of earth's movement through space or are distant objects in space approaching us? our 'movement' is relative (not absolute) - same with light.

It doesn't matter if you say "relative" speed because light has the same speed from all frames of reference oddly enough. If space time were moving, matter should be following that motion in some manner, but in order for us to measure multiple beams of light traveling in straight lines that would mean matter has to be moving in all those other directions simultaneously to constantly measure them at the speed of "c", which can't really happen.

Edited January 17, 2013 by SamBridge

[ACG52]

^{lets erase entirely the personal attack INITIATED against me by the gentleman}

 

 

^{I said you were 100 percent incorrect. And you are. I don't see that as a personal attack.}

 

^{BTW, Kaku had absolutely nothing to do with the development of string theory. If you're interested in the history of string theory, read The Elegant Universe By Brian Greene. (who did have quite a bit to do with string theory's development).}

[manderson]

i

 

 

^{I said you were 100 percent incorrect. And you are. I don't see that as a personal attack.}

 

^{BTW, Kaku had absolutely nothing to do with the development of string theory. If you're interested in the history of string theory, read The Elegant Universe By Brian Greene. (who did have quite a bit to do with string theory's development).}

 

i now understand you. you reason from the assumption that Relativity theory is immutable or at least correct - therefore you test what i say against that and if it does not fit you discard. that's not the type of discussion i was attempting to engage. i was proposing to the mind to disregard theories and simply reason and imagine. i know SR says speed is same against all reference frames, but i dont believe it and einstein himself in GR seem not to believe it either. I believe it only appears to be true because of our limitations...but as u are not willing to engage in imagining it will not be possible for us to discourse. How can we hold absolute beliefs about 4D & higher dimensions when we can only really conceive 3D? I believe doing so is very dangerous.

 

Thanks for sharing Brian Greene - Kaku claims he is co-founder of String Theory (i respect his thinking as i find his openness to be in line with genuine scientific tradition).

[SamBridge]

i

 

 

i now understand you. you reason from the assumption that Relativity theory is immutable or at least correct - therefore you test what i say against that and if it does not fit you discard. that's not the type of discussion i was attempting to engage. i was proposing to the mind to disregard theories and simply reason and imagine. i know SR says speed is same against all reference frames, but i dont believe it and einstein himself in GR seem not to believe it either. I believe it only appears to be true because of our limitations...but as u are not willing to engage in imagining it will not be possible for us to discourse. How can we hold absolute beliefs about 4D & higher dimensions when we can only really conceive 3D? I believe doing so is very dangerous.

 

Thanks for sharing Brian Greene - Kaku claims he is co-founder of String Theory (i respect his thinking as i find his openness to be in line with genuine scientific tradition).

No it's not limitations, it's because in order for matter to travel at the speed of light it would have to possess infinite energy, so going twice the speed of light is definitely impossible, and you can bet Einstein believed his most widely-known equation that has been used for all sorts of technology.

[manderson]

No it's not limitations, it's because in order for matter to travel at the speed of light it would have to possess infinite energy, so going twice the speed of light is definitely impossible, and you can bet Einstein believed his most widely-known equation that has been used for all sorts of technology.

 

no dispute there but everything is energy is it not? hence at the speed of light matter changes into pure energy. in fact there is no such thing as matter. i believe we believe 2c is impossible because we experience time uni-directionally (ie as a positive integer). at a higher dimension time by reasoning must exist bi-directionally (ie as both positive and negative integer - even if we can't experience it ourselves it must exist because everything must have an opposite. i personally believe we can experience bi-directional time: meaning we can go back in time (not as matter but as energic beings of consciousness - ie our true selves). i do not view myself as the body: i view the body as something in which i reside. i believe that i am an energetic being who in accordance with laws of thermodynamics cannot be destroyed. i believe my thoughts (evidenced by brainwaves) is a form of energy which travels at light speed. telepathy is a fact and US military is already using it. so while this may sound wonky to you, it would be much wiser to look into these ideas for your personal benefit. now of course you don't have to.

 

QUESTION: if u are the body, then what happens if i give u artificial arms, artificial legs, artificial organs, face transplant, etc (all of which are doable with current technology). once i artificially replace ALL your body parts: is it still you? so who are you? can u be destroyed? you is the inner being within....you are not the body...you are energy with consciousness...you are what religious people call God. i am not religious...i am just uniting the 2