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Science

The speed of light is an unbreakable barrier if your rest mass is greater than zero because it will take an infinite amount of energy to accelerate to the speed of light, according to Relativity.

Now, particles can exist whose nature is that they go faster than the speed of light.

Science fiction has given us several ways of breaking the speed of light including worm holes through space and creating fields around a ship in which the speed of light increases.

Ryan
 
Originally posted by: violetman
I know that if you can sum up up two speeds than you'll be able to overcame c🙂
It's not that hard....
Click to expand...



you need to use relativity, and summation can't give you a speed faster than the speed of light.
 
Originally posted by: violetman
I know that if you can sum up up two speeds than you'll be able to overcame c🙂
It's not that hard....
Click to expand...

No, you can't sum up two speeds and overcome c. Adding velocities is a consequence of newtonian physics, which applies at very low velocities. According to relativity, you can't simply go 3/4c and launch a rocket going 3/4c and go faster than light. The velocities aren't purely additive.

R

 
Originally posted by: violetman
i think it's possible.


I think that everything is possible.....
Click to expand...

Good for you... if you figure out how, you'll get the Nobel prize for physics.

R

 
Well, you can slow down light...but I don't think we've figured out how to accelerate a particle beyond the speed of light.
 
Originally posted by: rgwalt
The speed of light is an unbreakable barrier if your rest mass is greater than zero because it will take an infinite amount of energy to accelerate to the speed of light, according to Relativity.

Now, particles can exist whose nature is that they go faster than the speed of light.

Science fiction has given us several ways of breaking the speed of light including worm holes through space and creating fields around a ship in which the speed of light increases.

Ryan
Click to expand...

Even those, technically speaking, don't break the speed of light, they merely alter space to make the path shorter.
 
Originally posted by: Dr Smooth
Originally posted by: violetman
Can you overcome the speed of light?
In any way?
Click to expand...


I think the speed of light barrier is more an artifact of Einstein's math than reality.
Click to expand...

It truly is a reality, and the effects on time predicted by special relativity have been experimentally verified.
 
You need to research the following:

- Maxwell's equations
- Lorentz's transformations
- Lorentz contraction
- Lorentz time dilation
- And of course special relativity as it is largely derived from the above

You can say anything is possible, but that isn't science. Learn more about Lorentz's transformations and you'll find 'c' is always 'c' for inertial frames, if you do the math of course. Learn more about it here, or just read Einstein's Relativity.
 
I remember that my physics teacher told the class that you can't prove things in science, but in math. In science, you compare experimental results with theory, not prove. Maybe I heard him wrong; it was halfway into a boring, and yes I was a bit sleepy lecture.
 
Originally posted by: TechnoKid
I remember that my physics teacher told the class that you can't prove things in science, but in math. In science, you compare experimental results with theory, not prove. Maybe I heard him wrong; it was halfway into a boring, and yes I was a bit sleepy lecture.
Click to expand...

All science is based on fundemental assumptions that are suggested by experimentation, so the proof is not necessarily as solid as one that only relies on the postulates of set theory (as with abstract mathematics).
Special relativity makes two assumptions: Physics is the same in all inertial frames, and the speed of light constant for all inertial frames (something required by Maxwells equations). So far neither of these have been shown to have a single exception.
 
Originally posted by: ClueLis
Originally posted by: TechnoKid
I remember that my physics teacher told the class that you can't prove things in science, but in math. In science, you compare experimental results with theory, not prove. Maybe I heard him wrong; it was halfway into a boring, and yes I was a bit sleepy lecture.
Click to expand...

All science is based on fundemental assumptions that are suggested by experimentation, so the proof is not necessarily as solid as one that only relies on the postulates of set theory (as with abstract mathematics).
Special relativity makes two assumptions: Physics is the same in all inertial frames, and the speed of light constant for all inertial frames (something required by Maxwells equations). So far neither of these have been shown to have a single exception.
Click to expand...

Maxwell's equations were with respect to a rest frame (the aether), were they not? It was SR that postulated a Lorentz invariant for 'c' using the transformation without respect to a rest frame, was it not?
 
Originally posted by: TechnoKid
Well, you can slow down light...but I don't think we've figured out how to accelerate a particle beyond the speed of light.
Click to expand...


Even then light is not really going slower. The photon is being absorbed and emitted by atoms whose electrons have been bumped up an energy level and then emit a photon when they drop down. What I'm remembering from chem. So the AVERAGE speed through the material is slower but between atoms it's still going the speed of light?

I'm not sure how it works with the supercooled gases were they REALLY slow light down.
 
Originally posted by: Descartes
Originally posted by: ClueLis
Originally posted by: TechnoKid
I remember that my physics teacher told the class that you can't prove things in science, but in math. In science, you compare experimental results with theory, not prove. Maybe I heard him wrong; it was halfway into a boring, and yes I was a bit sleepy lecture.
Click to expand...

All science is based on fundemental assumptions that are suggested by experimentation, so the proof is not necessarily as solid as one that only relies on the postulates of set theory (as with abstract mathematics).
Special relativity makes two assumptions: Physics is the same in all inertial frames, and the speed of light constant for all inertial frames (something required by Maxwells equations). So far neither of these have been shown to have a single exception.
Click to expand...

Maxwell's equations were with respect to a rest frame (the aether), were they not? It was SR that postulated a Lorentz invariant for 'c' using the transformation without respect to a rest frame, was it not?
Click to expand...

True, I didn't mean to state that Maxwell's equations themselves stated that to be true, but that Maxwell's equations break down if we assume that light can have different speeds in different inertial frames, which was Einstein's motivation for developing special relativity.
 
Originally posted by: matt426malm
Originally posted by: TechnoKid
Well, you can slow down light...but I don't think we've figured out how to accelerate a particle beyond the speed of light.
Click to expand...


Even then light is not really going slower. The photon is being absorbed and emitted by atoms whose electrons have been bumped up an energy level and then emit a photon when they drop down. What I'm remembering from chem. So the AVERAGE speed through the material is slower but between atoms it's still going the speed of light?

I'm not sure how it works with the supercooled gases were they REALLY slow light down.
Click to expand...

It was in a popular science mag a long time ago, and yes, the article I read was where they passed a laser through a gas filled substrate (forgot exactly what gas) and the scientists could slow down light or even stop it, then "resume" it and the light would exit with the same way it came in, even after "stopping" it.
 
Originally posted by: TechnoKid
It was in a popular science mag a long time ago, and yes, the article I read was where they passed a laser through a gas filled substrate (forgot exactly what gas) and the scientists could slow down light or even stop it, then "resume" it and the light would exit with the same way it came in, even after "stopping" it.
Click to expand...

When the light was caught in the substrate, it managed to retain all of its values (frequency, direction, etc.) in the quantum state of the atoms that absorbed it, which then can be transferred back to light in the same form as before.

Here's a quick article with a decent description.
 
Originally posted by: ClueLis
Originally posted by: TechnoKid
It was in a popular science mag a long time ago, and yes, the article I read was where they passed a laser through a gas filled substrate (forgot exactly what gas) and the scientists could slow down light or even stop it, then "resume" it and the light would exit with the same way it came in, even after "stopping" it.
Click to expand...

When the light was caught in the substrate, it managed to retain all of its values (frequency, direction, etc.) in the quantum state of the atoms that absorbed it, which then can be transferred back to light in the same form as before.

Here's a quick article with a decent description.
Click to expand...

Thanks for the link :beer:
 
It has to do with the group velocity of a wave being related to the difference in velocities between phase velocities. In some gases (certain sodium ones especially), you can excite electrons to populate certain quantum states in the atoms, making it extremely difficult for light at those corresponding energies to pass through. You purposely leave a "gap" for light of a single frequency to get through. Thus the gas is transparent to only light in that one wavelength, and virtually opaque to even a slightly different wavelength. The resulting effect of having such drastic changes in transmission coefficients for such a small gap in energy results in having an extremely low group velocity for light through the gas. The phase velocity of the light is still c through the gas of course, but everything "conspires" to add and subtract portions of the waves so the "net effect" light wave travels very slowly through.

Simple analogy: You hold a rope at one end and send a wave along it by moving your arm up and down. I also have my hand on the rope near yours and send an opposite pulse along. The two pulses cancel out, resulting in no wave. Both pulses still travel down the rope, but you don't really see them. Now let's say that I put a pulse down the rope that NEARLY cancels yours out. It leaves a small blip near our hands, but then cancels out completely along the rest of the rope. So we have a little blip of wave at the start of the rope and nothing after that. Now, you send a continuous series of waves down the rope, and I do as well, but allow for a little blip each time. I figure everything out so that with our first wave the blip is very near our hands, and with the second wave the blip is very very slightly ahead. This continues and I just allow the blip to travel down the length of the rope at a very slow rate. Each of our waves travels quickly down the rope, but the resulting blip that results when we add our two waves moves much more slowly than the original waves do.
 
In 1867 Maxwell cast the basic equations of Electric and Magnetic fields in to the form of the wave equation. This was the first prediction that electromagnetic waves existed. 20 years later, based on this prediction, Hertz was finally able to generate and detect electro magnetic wave.

An interesting facet of the Wave equation is that the velocity of the wave shows up as an easily identifiable parameter. Maxwell found that the velocity of Electro Magnetic waves was given by the expression 1/Sqrt(e*m) where I have used the symbol e to represent Epsilon sub zero, the permittivity of free space and m is Mu sub zero the permeability of free space. These are basic constants of Electric and Magnetic fields which were experimentally know at that time. When Maxwell computed the numerical value of this speed, to his surprise, he found the number was equal to the best know value for the speed of light. This was the first bit of evidence that light was electro magnetic in nature.

This number (now called c) created quite a stir in the last half of the 19th century because it is a constant, it is a velocity that is not related to any other velocity. This created a division between the physics of material things and the physics of electromagnetism. Apparently the Galilean velocity transforms did not apply to electromagnetism. Up to that point in time they were assumed universally true.

It was not until Einstein published his Special Relativity that the 2 fields were reunited. Einstein was able to POSTULATE a constant c, BECAUSE Maxwell had predicted it and in there efforts to prove Maxwell wrong, Michelson and Morley verified the constancy of c experimentally.
 
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