Is there a 'Minimum' Speed of Light?

[Wave's_Hand_Particle]

And would this be a candidate for DarkMatter? or Zero Point Energy?

Tecnically if there was a Light Minimum, then this would be hard to detect, using Photons for instance.

 

[LURCH]

Not sure I understand the question, but I've read some experimients in which light has been stopped.

 

[KingNothing]

http://news.bbc.co.uk/1/hi/sci/tech/1124540.stm

 

[russ_watters]

Light travels at the speed of light. Period. And speed and energy are two completely different things: those other questions are utterly meaningless. Word salad.

 

[Wave's_Hand_Particle]

Light travels at the speed of light. Period. And speed and energy are two completely different things: those other questions are utterly meaningless. Word salad.

E-hum!

Feynman Fudge Factor?

https://www.physicsforums.com/showthread.php?t=57092

Pinch yourself and eat a little meat now and again!

 

[John King]

It would depend upon the reisstance it encounters, would it not?

 

[anti_crank]

Real photons travel at the speed of light. Period. As for virtual photons, we can't observe them by definition, so they can in principle do anything consistent with QED.

 

[Tom McCurdy]

Lights speed is constant... it does vary in mediums though... our physics teacher talked about where he was able to run past light when he was on the outside of an experiment and light was slowed to just a few m/s

 

[Mk]

Lights speed is constant... it does vary in mediums though... our physics teacher talked about where he was able to run past light when he was on the outside of an experiment and light was slowed to just a few m/s

Since light has no rest mass it is infinitely light, pardon the pun, meaning an infinitesimal amount of force is needed to accelerate it to the speed of light in the specified medium. Could you freeze a photon? Keep it still? Or would this interfere with the 3rd Law of Thermodynamics?

 

[sweetcaroline6]

To Russ Waters
If light travels a certain distance in space in a given time, is it possible that if space were contracted, light would travel over this "shortened" distance over the same time. i.e. to an outside observer it would appear to slow down. As gravity changes space, as one approaches a black hole, light would be slowed, but never stopped. Maybe that's why black holes are black, not because light can't escape but rather that light slows down on the way in and speeds up on the way out. We just haven't yet seen the light that is slowly coming out? So maybe there are black holes that are bright also; ones that the light has escaped.

 

[russ_watters]

Well, you could measure the distance from one frame and the time from another and get a number other than C, but that doesn't really fit the definition of "speed."

 

[lucien86]

Since light has no rest mass it is infinitely light, pardon the pun, meaning an infinitesimal amount of force is needed to accelerate it to the speed of light in the specified medium. Could you freeze a photon? Keep it still? Or would this interfere with the 3rd Law of Thermodynamics?

Light reaches a speed of zero all the time when it hits something.
I think you are seeing light wrongly, it is better to see it as a ripple in space time rather than as a massed object. Light is actually an oscillating electro-magnetic field - a wave, and in lots of ways it doesn't even exist. Above all though light is energy, E = m c^2 and for light everything is on the E side, this is because it is moving at the speed of light (obviously).

One aspect of this is that at the 'speed of light' you are at a point where time dilation is total : so to a photon time does not exist - it is destroyed the instant it is created.

An interesting idea is that matter may be formed in the same way, as a condensate of energy - not moving outside but moving at the speed of light inside.

 

[lawtonfogle]

If E=MC^2 and C=0 then matter could be converted into energy but the energy is not there for M*0=0 so E=0

in reverse matter could come from nothing in a place where the speed of light is zero

 

[lawtonfogle]

when a ball bounces off an object there is an amount of time where the ball has no speed

now replace the ball with light, so when light hits an object light stops for an amount of time. During that amount of time matter can be created with no energy imput

this means that matter only exist because light must bounce off of it and that light only bounces off matter that is exsiting

this forms an continuing effect that never ends and cannot have an beginnig (at leat a beginning caused by normal energy or matter (anti or not))

 

[Gamish]

E=mc^2

If E=MC^2 and C=0 then matter could be converted into energy but the energy is not there for M*0=0 so E=0

in reverse matter could come from nothing in a place where the speed of light is zero

When "E=mc^2" is used, c must be the speed of ligh in a vaccume.

Im the master at time!

 

[lawtonfogle]

Does not C depend on where the matter chaning into energy is at.

 

[Wave's_Hand_Particle]

If E=MC^2 and C=0 then matter could be converted into energy but the energy is not there for M*0=0 so E=0

in reverse matter could come from nothing in a place where the speed of light is zero

Interesting?..when Light is Parametrically Downconverted, say for instance at the Horizon of a Blackhole, then as you state, the process of Matter Creation is viable. Hawking Radiation is the invisible product of Light turning into Dark?..maybe?

 

[hypermorphism]

now replace the ball with light, so when light hits an object light stops for an amount of time. During that amount of time matter can be created with no energy imput

Photons that "hit" particles are either absorbed or ignored. They don't bounce.

 

[lawtonfogle]

Mr. Hypermorphism, you are saying there is not a point of time where light has a speed of 0. What about at the moment that the photon is absorbed or released or ignored.

 

[hypermorphism]

Mr. Hypermorphism, you are saying there is not a point of time where light has a speed of 0. What about at the moment that the photon is absorbed or released or ignored.

Before the photon is absorbed, it is moving at c. A real photon released from a particle travels at c, since it is massless. The real photon doesn't accelerate from rest like a massive particle would.

 

[lawtonfogle]

So then you are saying no.


Well on to the subject that scientist are slowing down the photons, if they stopped them would not the E=MC^2 where C=0 problem still happen.

 

[Keromane]

Slowing down photons c.q. different light speeds in different media has nothing to do with the speed of light itself. The measured speed tells something about the 'fabric' of spacetime, its density. Density differences due to mass, temperature and who knows what interesting things to be discovered. Experiments like these map our universe a bit further, give us clues.

A photon cannot be compared to a complex entity like a ball. Besides that, Newtonian physics is not valid regarding quantum mechanics. When a photon 'hits' a surface it's speed is not set to 0. As said earlier in this topic, consider light as ripples in spacetime.

 

[lawtonfogle]

So you are saying that C is a constant?

If it is we have one thing.
If it isn't we have another.

Has the E=MC^2 ever been proven, or has it not yet been disproven.

 

[sweetcaroline6]

surely when light hits an object it's energy is absorbed into that object and if light returns in kind it is new light manufactured by the object using the energy of the light that it has just absorbed. so light's speed is never zero.
also (and this is to russ re my last question) how, in the scenario of the black hole described am i measuring time and speed from different frames?
many thanks

 

[russ_watters]

So you are saying that C is a constant?

If it is we have one thing.
If it isn't we have another.

Has the E=MC^2 ever been proven, or has it not yet been disproven.

C is a constant. That was first proven by the Michelson Morley experiment in the late 1800s and there were indications of it (from Maxwell's equations) before it was proven. It was just assumed to be a flaw in Maxwell's equations, but it turned out they were right.

Mass/energy equivalency has also been thoroughly proven: its the basis for, among other things, nuclear power. It's also tested every time a particle accelerator is operated.

surely when light hits an object it's energy is absorbed into that object and if light returns in kind it is new light manufactured by the object using the energy of the light that it has just absorbed. so light's speed is never zero.

All correct.

also (and this is to russ re my last question) how, in the scenario of the black hole described am i measuring time and speed from different frames?
many thanks

Black holes (and all other objects with mass) do indeed sap energy from light traveling away from them. That is manifested by a red-shift in the light: the energy of the light is reduced, while the speed stays the same. One of the ways of detecting the black holes is by observing the red-shift of light emitted by matter orbiting or falling into an unseen object.

Also, with time dilation being frame dependant, its important not to mix frames when calculating speed: if you consider the time dilation of a frame near a black hole and distance as measured from earth, you may calculate the wrong speed of light.

 

[DB]

If light travels a certain distance in space in a given time, is it possible that if space were contracted, light would travel over this "shortened" distance over the same time. i.e. to an outside observer it would appear to slow down. As gravity changes space, as one approaches a black hole, light would be slowed, but never stopped. Maybe that's why black holes are black, not because light can't escape but rather that light slows down on the way in and speeds up on the way out. We just haven't yet seen the light that is slowly coming out? So maybe there are black holes that are bright also; ones that the light has escaped.

Light is not slowed, it is redshifted. When light enters gravitational fields, it uses up energy to continue traveling at c. When it loses energy its wavelenght is increased and is therefore "more red". Light can be refracted, absorbed, emited etc. but all at c.

 

[DB]

Oops, russ got their first.

 

[ElectroPhysics]

I bet u people can't stop or lower the speed of light in vacuum.

 

[hemmul]

And would this be a candidate for DarkMatter? or Zero Point Energy?

Tecnically if there was a Light Minimum, then this would be hard to detect, using Photons for instance.

he-he a slightly different question born after a severe hangover:
if there is a maximal speed of information transfer (speed of light) is there a corresponding minimal speed? :)

 

[ElectroPhysics]

Hemmul:
Yes it is possible in nature...