Faster than the speed of Light?

Light's particle is the photon which is believed to be an elementary particle.  I don't even pretend to understand the wave-particle duality of light so I can't really answer any of your other questions.

Richard Feynman, in his classic Lectures on Physics, explains the actual math about as simply as I've ever seen it done.  

Here's a summary from Vol I, Lecture 16 (via Wikipedia)

Composition of velocities

If the observer in S sees an object moving along the x axis at velocity w, then the observer in the S' system, a frame of reference moving at velocity v in the x direction with respect to S, will see the object moving with velocity w' where

This equation can be derived from the space and time transformations above.

Notice that if the object were moving at the speed of light in the S system (i.e. w = c), then it would also be moving at the speed of light in the S' system. Also, if both w and v are small with respect to the speed of light, we will recover the intuitive Galilean transformation of velocities: .

The usual example given is that of a train (call it system K) travelling due east with a velocity v with respect to the tracks (system K'). A child inside the train throws a baseball due east with a velocity u with respect to the train. In classical physics, an observer at rest on the tracks will measure the velocity of the baseball as v + u.

In special relativity, this is no longer true. Instead, an observer on the tracks will measure the velocity of the baseball as . If u and v are small compared to c, then the above expression approaches the classical sum v + u.

I appreciate your answer. I see. I am still learning too. :3

I see this is an old discussion. I have a curious nature, like Taodell, and many of these FTL, Schwarzheide type Black Hole theories, wormholes, etc. have fascinated me for quite some time. I never got much past my freshman Physics and Calculus, but I like to suggest ideas.

I think Taodell's idea about FTL being a reality between two approaching light beams is an interesting subject and one I hadn't considered before.

A couple things pop into my mind:

1. I think Taodell's analogy of that collision to pool balls was off, because what makes one pool ball accelerate and the other decelerate is the fact that pool balls that accelerate after a collision were usually at rest before the collision. Two objects approaching each other and colliding will not gain momentum that causes them to increase speed, in general. And we didn't need Einstein or Lorenz to tell us that, I think Newton and possibly some of his predecessors were pretty well aware of that.

2. Even tho i don't see how that collision would cause FTL to occur, I still think that we must have zillions of collisions going off at a pretty good rate between all these photons travelling from all these stars and bumping into each other. What becomes of those little guys?

FTL is not possible because in the Lorentz transformations there is the nice sqrt(1-v^2/c^2) ,for example the mass transformation for speed v is gien by M=m/sqrt(1-v^2/c^2),where M is the mass that the object has while moving with v relative to a system at rest,and m is the mass of the object at rest.What happens if you put in this simple equation a value for v>c?Then we'll have some complex solutions,and that's a problem.

And about the cold ,empty vacuum:space is not empty at all,there are lots of photons and neutrinos out there,and cosmic rays coming from the big bang(cosmic background radiation),and from supernovas(beta and gamma -rays,protons and pozitrons and a lot more)And if a small enough region of space contains enough energy then particles will be produced(remember E=mc^2).This is Virtual Pair Production,when a particle and antiparticle is created from pure energy and then they collide again to transform back to energy again.

If you are still thinking about FTL then think about time dilation.The faster you go,the slower time passes.Here is a simple equation:T=t*sqrt(1-v^2/c^2),where T is time when moving and t is time when at rest.When v=c(or v->c) then T=0(T->0).So time will essentially stop.Something like this happens inside a black hole.Time is affected by gravity,the greater the gravitaional  pull,the slower time passes(General Relativity),and of coure it can catch light beams.From a black hole light cannot escape so the gravitational pull of the black hole is greater,that means that time will stop inside a black hole.

I would like to understand GR but I think that I will need some help.Is there anyone who knows the math of GR so I can ask some questions while I'm studying it?Thanks.Btw ,nice group,I'm happy to be here.

by Eternal_Patzer
United States

Member Since: Mar 2009

This is hilarious.   Taodell has got people swallowing this thread hook line and sinker.  Folks are even trying to explain relativity to him.    

This is right up there with some of Beast719's best threads!    "

Ok. I'm not really sure how I should take that.  I'm a con-man?  And this being a thread I initiated why would you refer to me as if I weren't here. Almost as if you were addressing yourself.

"Right up there" sounds good, or is it?  What if the "up" were up the river?

Ok, ZekesGhost, pool balls and a glancing blow might not accomplish what I was after, but how about this:  Two objects traveling at near light speed are colliding head on.  These are spherical massive objects, non-elemental. As the collision progresses (in the nearly timeless instant it takes) the leading surfaces will meet, compress, and the objects will flatten. When the back of the objects reach the impact point their masses will be explosively hurled laterally at greater than the speed of light.

   And Ripper89,  "FTL is not possible because..."    You can say FTL is thought not to be possible because...   

   That is some pretty heavy math though. I found it easier to understand if I plugged in some actual figures.

   And you are right that space is full of different rays which could possibly slow an object. However, those particles are so near massless that even at those speeds their impact would be negligible except in huge quantity.

Apologies, taodell.  When I first read this thread I really thought you were just pulling everyone's collective leg, pretending not to believe relativity, just to see if you could stir something up.

The reference to Beast719 is really a compliment, since he is one of the funniest posters on Chess.com and one of my favorites.  I thought the whole thread was a spoof of the sort he might start (minus the Welsh references, of course).

No offense intended, I assure you.

Relativity theory is just a good night story, space can't have properties, it can't be "big", or have limits, it can't be bent. Mater anti-matter and energy is (or trying) to be in perfect balanse.

Even if C limit is true you CAN'T move faster than speed of light, but the universe around you can

Oooh!  Cosmo-smack!  I love it.

How about space-time?  Can it have properties?

Well after traveling daily to school, few hours of thinking, I could narrow the choice:

A:There is 1 dimenison- all "other" dimensions are actually the same

B:Infinetly many dimensions

C:No "keine" dimensions

But better stop before they declare me heretic :)