Faster than the speed of light

[cobrastrike]

Is it possible to go faster than the speed of light? And why do some scientists say you can't?
Thanks -_-!

 

[DaveC426913]

Is it possible to go faster than the speed of light? And why do some scientists say you can't?
Thanks -_-!

Nothing with mass can accelerate to the speed of light. The closer you get to it, the more energy it will take to get closer. It is an asymptotic limit.

 

[Cosmos2001]

Nothing with mass can accelerate to the speed of light. The closer you get to it, the more energy it will take to get closer. It is an asymptotic limit.

Hence, anything without mass can be faster than light: velocity of phase/group of EM waves, gamma-ray burst, neutrinos, and also initial acceleration of light (m/s² → v/t ), light’s initial acceleration shouldn’t exceed an acceleration of c (v/t), but it exceeds because it has no mass.
Extending this thought, if something has no mass then it can be faster than light, hence I thought it is logic the theory, that is said already observed in practice, that static fields (magnetic and electric) are at least 20 billion times faster than light.
As well, http://www.youtube.com/watch?v=Z8Hwqg9_oA8", which can be mathematically verified (f≥c/L)

As far as I could understand, "Nothing can be faster than light", except if it has no mass or negative mass.
My question is, could phase-shifted oscillations produce a kind of negative mass effect?

 

[K^2]

No. Anything with no mass travels AT the speed of light. E.g. light.

 

[DaveC426913]

Hence, anything without mass can be faster than light: velocity of phase/group of EM waves, gamma-ray burst, neutrinos,

No, this does not follow.

and also initial acceleration of light (m/s² → v/t ), light’s initial acceleration shouldn’t exceed an acceleration of c (v/t), but it exceeds because it has no mass.

Light does not accelerate. It is emitted at c.

Extending this thought, if something has no mass then it can be faster than light,

It can't.

hence I thought it is logic the theory, that is said already observed in practice, that static fields (magnetic and electric) are at least 20 billion times faster than light.

No. Fields are pervasive - as in: they already exist everywhere. Changes to those fields are propogated at the speed of light.

As well, http://www.youtube.com/watch?v=Z8Hwqg9_oA8", which can be mathematically verified (f≥c/L)

Certain groups of things, such as wave pulses can propogate faster than c, but these are a special case. Nothing real (mass or massless) is actually moving faster than c, and no information can be transmitted faster than c. It is much like sweeping a beam of light in an arc. The spotlight can be seen to be moving faster than c, but the spotlight is simply a group of things - no thing is exceeding c, including information.

 

[Dremmer]

Yes, it is. Space does it all the time.

 

[skeptic2]

In quantum mechanics there are effects that can be described by assuming virtual particles traveling faster than light. Still these virtual particles transmit no information and cannot be used for communication.

 

[Cosmos2001]

Light does not accelerate. It is emitted at c.

Acceleration is the rate of change of velocity over time (∆v/∆t), hence, how could the light be emitted, with instantaneous speed up to c, without initial acceleration?

 

[f95toli]

Because light does not follow the usual "rules" that apply for e.g. footballs. Light just "is" and always travel at c.

(a more scientific answer is that a photon is just an excitation of a tempora-spatial mode, i.e. that mode -which "travels" at c- either is or isn't occupied)

 

[Cosmos2001]

Because light does not follow the usual "rules" that apply for e.g. footballs. Light just "is" and always travel at c.

(a more scientific answer is that a photon is just an excitation of a tempora-spatial mode, i.e. that mode -which "travels" at c- either is or isn't occupied)

From what I have understood, then, is there a kind of “slot” that always travels at c, independently whether it is occupied by a photon or not?

 

[ninjanik18]

doesn't it depend where? I think I heard that apparently in this universe you can't travel faster than the speed of light whereas outside this universe you can, such as the 11th dimension (I think) that we are expanding in, didn't the universe start expanding faster than the speed of light?

p.s. I am only 15

 

[russ_watters]

Acceleration is the rate of change of velocity over time (∆v/∆t), hence, how could the light be emitted, with instantaneous speed up to c, without initial acceleration?

T=0 therefore v/t= undefined

 

[Danger]

I feel obliged here to point out, as Dave alluded to, that the speed limit of light applies only to a vacuum situation. All manner of things can exceed it in a medium. Even that is deceptive, though. Individual photons within media still travel at c, but their journey is interrupted so much that the overall signal proceeds much slower. (I think that such is called "group velocity".)
Check out Cherenkov radiation as an example.
Resident scientists, I have quite a record for using incorrect terminology when trying to express myself, so please feel free to correct such.

 

[FredT]

A friend of mine posed the question that if light is affected by the gravity of a black hole, couldn't the slingshot effect accelerate light?

 

[DaveC426913]

A friend of mine posed the question that if light is affected by the gravity of a black hole, couldn't the slingshot effect accelerate light?

Nope. Light does not accelerate when subjected to gravity; it simply curves along the geodesic.

A massive object can be placed stationary with respect to a gravitational object such as Earth or a BH. From that point, it will begin to accelerate, due to the curvature of space toward the object. But you cannot place a beam of light stationary wrt a gravitational object, thus it does not accelerate toward it.

 

[DaveC426913]

Yes, it is. Space does it all the time.

"Space" doesn't "do" anything, including "go" anywhere. Things in space do things and go places.

Even when the universe is expanding, there is no "fabric" that is moving. It is simply that objects far apart are getting farther apart.

 

[DaveC426913]

From what I have understood, then, is there a kind of “slot” that always travels at c, independently whether it is occupied by a photon or not?

No. Not sure where this slot came from.

 

[Cosmos2001]

T=0 therefore v/t= undefined

I think it is not undefined; it is infinity.
v/t ⇒ S/t²
lim (1/t²) = +∞
t→0
http://en.wikipedia.org/wiki/List_of_limits#Simple_functions

 

[DaveC426913]

I think it is not undefined; it is infinity.
v/t ⇒ S/t²
lim (1/t²) = +∞
t→0
http://en.wikipedia.org/wiki/List_of_limits#Simple_functions

Regardless, the photon moves at c and only c. Photons do not experience time.

 

[Cosmos2001]

Regardless, the photon moves at c and only c. Photons do not experience time.

However, observers experience time. Would an observer see an emitted photon as it had acquired instantaneous velocity c in a time close to zero, observing infinity acceleration?

 

[DaveC426913]

However, observers experience time. Would an observer see an emitted photon as it had acquired instantaneous velocity c in a time close to zero, observing infinity acceleration?

Yes (if an observer could "see" a photon emitted, which is challenging).

 

[K^2]

From what I have understood, then, is there a kind of “slot” that always travels at c, independently whether it is occupied by a photon or not?

In quantum electrodynamics, yes. The state of a traveling photon always exists. When you "create" a photon, you merely excite that state. That's called the second quantization of electromagnetic field. So in a way, looking at it as something that always travels at c and you simply flip it on and off is consistent with our understanding of electromagnetic wave.

Just keep in mind that you're getting very close to the slippery edge of a rabbit hole that is quantum gravity.

 

[Danger]

Just keep in mind that you're getting very close to the slippery edge of a rabbit hole that is quantum gravity.

:rofl:

That has to be one of the best statements that I've ever seen.

 

[AdkinsJr]

Light does not accelerate. It is emitted at c.

.

hmmmm, that's interesting. So if light is slowed down as it passes through a medium, does this mean that it isn't accelerating although there's a change in velocity? That's rather strange to me...

If light can't accelerate, then forces cannot act on light, is that true? The definition of a force (as I know it) is something that causes an acceleration...

 

[Danger]

hmmmm, that's interesting. So if light is slowed down as it passes through a medium, does this mean that it isn't accelerating although there's a change in velocity? That's rather strange to me...

If light can't accelerate, then forces cannot act on light, is that true? The definition of a force (as I know it) is something that causes an acceleration...

As I mentioned earlier, the individual photons still travel at c. Even during their absorption and re-emission, their acceleration is instantaneous. Because of those "detours", however, the group velocity of the light is lowered.

 

[Drakkith]

Perhaps this can help. I read or saw this somewhere, i can't remember where.

There is an absolute speed limit in the universe. The value of that speed is exactly how fast that light travels in a vacuum, also known as "c". Nothing can travel faster than this. Light, having 0 mass, simply travels as fast as it can always, which is why this speed limit is called the "Speed of Light".

Now, since light has 0 mass, it can be accelerated at the maximum possible amount no matter how much energy is supplied. Thus, it is accelerated "instantly" to it's maximum speed when it is emitted at any frequency.

When light is effected by gravity, it isn't accelerated as it is already moving as fast as possible. I look at it like this: The light is "turned" in a new direction by gravity, which causes it to be bent around objects with mass. The higher the mass, the harder the "steering wheel" is turned. This is similar to the the direction an object is traveling while in orbit around something. Its direction is always changing as it orbits. Note that the velocity of the object will increase or decrease, as it does have mass and isn't traveling at c.

Thats just my 2 cents.

 

[K^2]

hmmmm, that's interesting. So if light is slowed down as it passes through a medium, does this mean that it isn't accelerating although there's a change in velocity? That's rather strange to me...

If light can't accelerate, then forces cannot act on light, is that true? The definition of a force (as I know it) is something that causes an acceleration...

In medium, the actual photons still travel at the speed of light. They are simply constantly absorbed and re-emitted. That gives you phase shifts equivalent to light wave slowing down. So the particles never decelerate. I know it sounds like a dirty fix to a serious problem, but it was invented by nature, not scientists.

 

[russ_watters]

I think it is not undefined; it is infinity.
v/t ⇒ S/t²
lim (1/t²) = +∞
t→0
http://en.wikipedia.org/wiki/List_of_limits#Simple_functions

Infinity is not a number - that's why it is undefined.

 

[HallsofIvy]

A friend of mine posed the question that if light is affected by the gravity of a black hole, couldn't the slingshot effect accelerate light?

Acceleration is a change in the vector velocity. it can be a change in speed (the magnitude of the velocity vector) or a change in direction (or both). Light always travels at speed c. Acceleration can only change its direction.

 

[K^2]

Light can get a slingshot boost from a moving black hole, yes, but it will result in frequency shift, rather than change of speed. Keep in mind that slingshot effect is a momentum transfer. If you transfer momentum to a massive object, it changes velocity. If you transfer momentum to a zero-mass object, like photon, it changes its frequency.

 

[christopherV]

Does a photon actually travel faster than c during quantum tunneling? Where does the extra energy come from if a photon is massless? I am still unclear on this...

 

[Cosmos2001]

"Nothing with mass can accelerate to the speed of light. The closer you get to it, the more energy it will take to get closer. It is an asymptotic limit."
"No. Anything with no mass travels AT the speed of light. E.g. light."
"Light does not accelerate. It is emitted at c."
"Regardless, the photon moves at c and only c. Photons do not experience time."
"As I mentioned earlier, the individual photons still travel at c."
"In medium, the actual photons still travel at the speed of light."

Excuse me, but always I read it; it sounds like dogmas to me that cannot be proven or disproven.
How to make sure, in fact, that “Nothing can be faster than light” only based on particle accelerators that can only accelerate charged particles, that is unable to make tests accelerating neutrons and small neutral bodies, which are not so easily slowed down by magnetic and electric fields? And, worst, even knowing that velocity of phase/group of EM waves, gamma-ray burst, neutrinos, and tachyons, are said to be faster than light?

 

[Dale]

it sounds like dogmas to me that cannot be proven or disproven.

Your ignorance of the experimental results does not imply that the experimental results do not exist. See the sticky on the experimental basis of SR for a good concise overview. Many experiments involve high speed neutrinos and neutrons from various nuclear reactions, so your assertions about only using charged particles are incorrect. There are also experiments with large objects like satellites and planes which are also electrically neutral.

 

[Cosmos2001]

Your ignorance of the experimental results does not imply that the experimental results do not exist. See the sticky on the experimental basis of SR for a good concise overview. Many experiments involve high speed neutrinos and neutrons from various nuclear reactions, so your assertions about only using charged particles are incorrect. There are also experiments with large objects like satellites and planes which are also electrically neutral.

Well, the minimum amount of energy required to accelerate a neutron close to speed of light:
neutron=1.67493×10^-27 kg
c=299792458 m/s
E=½mv²
E_J=½(1.67493×10^-27)(299792458)² =75.26760×10^-12J
E_eV=75.26760×10^-12/1.60218×10^-19 = 469.78242×10⁶ = 470MeV

The average energy released in fission of one Pu-239 atom is 210MeV, emitted neutrons 5.9MeV which is very far from 470MeV, there is not enough energy to emit neutron close to speed of light.
http://en.wikipedia.org/wiki/Plutonium-239#Nuclear_properties

My question is: are there atomic nucleuses that emit neutrons having kinetic energy exceeding 470MeV?

 

[DaveC426913]

Well, the minimum amount of energy required to accelerate a neutron close to speed of light:
neutron=1.67493×10^-27 kg
c=299792458 m/s
E=½mv²
E_J=½(1.67493×10^-27)(299792458)² =75.26760×10^-12J
E_eV=75.26760×10^-12/1.60218×10^-19 = 469.78242×10⁶ = 470MeV

The average energy released in fission of one Pu-239 atom is 210MeV, emitted neutrons 5.9MeV which is very far from 470MeV, there is not enough energy to emit neutron close to speed of light.
http://en.wikipedia.org/wiki/Plutonium-239#Nuclear_properties

My question is: are there atomic nucleuses that emit neutrons having kinetic energy exceeding 470MeV?

Is this your attempt to overturn the "dogma" that massive objects cannot reach or exceed c?

I'll just stop you right there.