Faster than the speed of light

[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.

 

[Dale]

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?

First, you need to learn the right formulas. E=½mv² is the non-relativistic kinetic energy not the relativistic kinetic energy. 470 MeV of KE accelerates a neutron to about .75 c (gamma factor 1.5).

Second, that amount of energy would result in approximately a 50% deviation from classical behavior. Well designed experiments can easily be made to detect deviations from classical behavior of less than 1% which would correspond to a KE of less than about 9 MeV.

Third, if you have a high KE particle which undergoes a nuclear reaction and releases a neutron then the KE of the neutron will be more determined by the high KE of the original particle than by the energy released from the nuclear reaction. This is how most high energy neutrons are actually produced in the lab.

 

[DaveC426913]

First, you need to learn the right formulas.

Yep. Nothin' like the internet for being told how wrong you are by someone who doesn't know what they're talking about...

 

[Cosmos2001]

First, you need to learn the right formulas. E=½mv² is the non-relativistic kinetic energy not the relativistic kinetic energy. 470 MeV of KE accelerates a neutron to about .75 c (gamma factor 1.5).

Second, that amount of energy would result in approximately a 50% deviation from classical behavior. Well designed experiments can easily be made to detect deviations from classical behavior of less than 1% which would correspond to a KE of less than about 9 MeV.

Third, if you have a high KE particle which undergoes a nuclear reaction and releases a neutron then the KE of the neutron will be more determined by the high KE of the original particle than by the energy released from the nuclear reaction. This is how most high energy neutrons are actually produced in the lab.

“470 MeV of KE accelerates a neutron to about .75 c (gamma factor 1.5)”
Is it a fact? Or supposition by indirect means?
How to make sure, in fact, that a neutron having more than 470 MeV of KE will not exceed the speed of light?

It's just science! I only want to know the truth of it all.

 

[M. Bachmeier]

Inflation, before the rules were set for this bubble. If you could or can stand outside this 'sub-universe' time with respect to our 'sub-universe' would be non-relevant, so you could reenter our 'sub-universe' at any point of choosing (no-time), assuming the 'mega-universe' has a time scale independent, which it would need to have in order to exist. Otherwise your out of luck.

 

[Drakkith]

“470 MeV of KE accelerates a neutron to about .75 c (gamma factor 1.5)”
Is it a fact? Or supposition by indirect means?
How to make sure, in fact, that a neutron having more than 470 MeV of KE will not exceed the speed of light?

It's just science! I only want to know the truth of it all.

Have you tried to look up anything on relativistic motion or on Relativity in general? Spending maybe an hour on Wikipedia or similar sites will greatly expand your knowledge on the subject. Typing in "What is Relativity" in google is a good starter too. Or anything on youtube when you type in Relativity.

Be aware that the subject of Relativity can be very complicated and non-intuitive, and as such can be difficult to understand for the average person. But realize that this isn't unsupported brainstorming by a mad scientist or anything, it is fully supported by current and past experiments and observations.

Edit: To put it in basics, accelerators have accelerated particles to higher and higher speeds, getting to within about 99% of the speed of light. The energy required to do this is drastically more than the non relative formula in your post above. Once you plug in the correct formula, it works out perfectly. Look up the Large Hadron Collider if you'd like to know more.

 

[DaveC426913]

Is it a fact? Or supposition by indirect means?
How to make sure, in fact, that a neutron having more than 470 MeV of KE will not exceed the speed of light?

It's just science! I only want to know the truth of it all.

Cosmos, SR is one of the most rigorously tested theories in the history of science. It has passed with flying colours every time.

We see particles undergo dilation and all other relativistic effects in accelerators every day, exactly in accordance with our models.

Not only are we sure it works the way our models show, but we build modern everday consumer technology counting on it working. If it did not work they way our models show, your GPS system in your car would not work. The software must take into account the SR and GR effects to get an accurate reading.


And it's time for me to change my sig line.

 

[Dale]

“470 MeV of KE accelerates a neutron to about .75 c (gamma factor 1.5)”
Is it a fact? Or supposition by indirect means?
How to make sure, in fact, that a neutron having more than 470 MeV of KE will not exceed the speed of light?

It's just science! I only want to know the truth of it all.

High energy neutrons from cosmic rays have been detected with energies in the range of 10^12 MeV without exceeding the speed of light. What's more, relativistic effects have been measured in macroscopic neutrally-charged objects like airplanes and satellites. If you really want to know the truth of it all then look at the evidence:

http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

 

[Cosmos2001]

High energy neutrons from cosmic rays have been detected with energies in the range of 10^12 MeV without exceeding the speed of light. What's more, relativistic effects have been measured in macroscopic neutrally-charged objects like airplanes and satellites. If you really want to know the truth of it all then look at the evidence:

http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

I know that, in particle accelerators, both negatively and positively charged particles need an outrageous energy (GeV, TeV, or much more) to attain to 99% of the speed of light. And particle accelerators are unable to accelerate neutrons. I think fast charged particles are easily slowed down by electric and magnetic fields, while fast neutrons are not so easily slowed down.

Hence, if fast neutrons are not so easily slowed down by electric and magnetic fields, and using the non-relativistic formula it is needed 470 MeV to attain to speed of light, and even with 10^12 MeV it does not exceed the speed of light, then “Nothing with mass can accelerate to the speed of light”, in fact, can be true.
DaleSpam, please, I’m not finding out the info 10^12 MeV, could give me more direct links?

 

[inflector]

DaleSpam, please, I’m not finding out the info 10^12 MeV, could give me more direct links?

Try googling: cosmic ray

or: oh my god particle

or: high-energy cosmic ray

 

[DrGreg]

Nobody has yet explicitly pointed out that the relativistically correct formula for kinetic energy is

mc^2 \left( \frac{1}{\sqrt{1 - \frac{v^2}{c^2}}} - 1\right)​

(not ½mv²) which increases without limit as v \rightarrow c.

Relativistic kinetic energy of rigid bodies

 

[Brown Arrow]

as dave said nothing with mass can reach the speed of light b/c as you gain speed you mass increases, hence slowing you down... but IF you can travel at or more than the speed of light... the world would make no sense; you would see effect before cause.

 

[MattRob]

Haha, Merlin would tell you that's perfectly normal, Brown Arrow.

Anyways, fact of the matter is, no matter is going the speed of light. Period. Intrinsic fact of the universe. Absolutely impossible. There's no reason to discuss it.

Now, being at A and later being at point B in less than the amount of time it'd take for light to get from point A to point B, that's a different story. By that definition, you should start looking for "loopholes" in physics, such as wormholes, quantum tunneling, etc. That's where this discussion should be. We're wasting time on trying to get to the speed of light by stomping on the gas. Won't happen.

So, what's the deal with Hiem theory? Disproven, eh? Could it be fixed to work?
More importantly, could the part about rotating into higher dimensions with magnetic fields somehow work?

That's what I want to know. What about rotating into higher dimensions, according to string theory, which bears quiet some weight nowadays, there are 11 dimensions. How come we're restrained to just 3?

I also remember reading an article somewhere about how it might be possible with the brane theories to create a small universe. If you could do that, could you somehow "ride" the expansion outward at the speed of light and re-enter our universe?
Better yet, how do you determine WHERE you would re-enter our universe?

And finally, back to higher dimensions. If you rotate up, and give up your X dimension for a higher dimension, then what determines your pivot point when you rotate back into our 3d space? Could you somehow influence where your pivot point is so you rotate back light-years away from where you rotated in?

 

[Brown Arrow]

Haha, Merlin would tell you that's perfectly normal, Brown Arrow

i don't get it?

 

[Dale]

DaleSpam, please, I’m not finding out the info 10^12 MeV, could give me more direct links?

Here is a classic with the full text. It only goes up to 10^6 MeV, but that is still far higher than your 470 MeV threshold that you are worried about.
http://www.physics.mcgill.ca/~mccutchm/Papers/Hess_1959.pdf

Here is a more recent reference for at least energies around 10^13 MeV, but it is paid access.
http://prd.aps.org/abstract/PRD/v31/i3/p564_1

There is just no way that your position that relativistic effects only happen for charged particles is compatible with the evidence. It is contradicted by data from ultra high energy neutrons and also data from macroscopic uncharged bodies.

 

[Phrak]

Regardless, the photon moves at c and only c.

That depends on who you are talking to; Maxwell, or Feynman.

 

[Cosmos2001]

Well, I’m aware that the subject of Relativity is very complicated and non-intuitive; I will take time to get full understanding of all its nuances.
Recovering:

“No. Anything with no mass travels AT the speed of light. E.g. light.” – K^2
“Regardless, the photon moves at c and only c. Photons do not experience time.” – DaveC426913
“As I mentioned earlier, the individual photons still travel at c.” – Danger
“In medium, the actual photons still travel at the speed of light.” – K^2
“Nothing can locally travel faster than light” – Miguel Alcubierre

Presuming “nothing can move faster than light” is a true fact “fully supported by current and past experiments and observations”.

Hypothesis:
Having an array of dipoles, floating in the deep space, producing spaced-apart phase-shifted oscillations, generating strong/energetic “moving electrodynamic wave packet” along the array length, where the velocity of the “moving wave packet” is given by v=Lf (ref.: multiphase linear motors), where v is the velocity, L is the array length, and f is frequency.
If (f > c/L) then (v>c) and (∆v=v-c)

Keeping energy flow enough to keep acceleration (∆v/∆t):
E=½m(∆v)²

If “Nothing can move faster than light” then, applying enough energy flow, will (∆v=v-c) be converted effectively into acceleration contrary to direction of the “moving wave packet”? How much percent (0%-100%) is the chance of it being true?

 

[Dale]

Hypothesis:
Having an array of dipoles, floating in the deep space, producing spaced-apart phase-shifted oscillations, generating strong/energetic “moving electrodynamic wave packet” along the array length, where the velocity of the “moving wave packet” is given by v=Lf (ref.: multiphase linear motors), where v is the velocity, L is the array length, and f is frequency.
If (f > c/L) then (v>c) and (∆v=v-c)

Sure, nothing is wrong with this. In this case v is the phase velocity of the wave, which is not limited to c and does not violate SR in any way as no matter, energy, or information is traveling faster than c.

Keeping energy flow enough to keep acceleration (∆v/∆t):

What is being accelerated here? The phase velocity is not the velocity of any object and so it doesn't need any time to accelerate.

 

[Cosmos2001]

Sure, nothing is wrong with this. In this case v is the phase velocity of the wave, which is not limited to c and does not violate SR in any way as no matter, energy, or information is traveling faster than c.

What is being accelerated here? The phase velocity is not the velocity of any object and so it doesn't need any time to accelerate.

In an initial case, v is more the velocity of the “moving electrodynamic wave packet” that is being generated by the array of dipoles that is adjustable v=Lf (ref.: multiphase linear motors)

The array of dipoles is that which have mass and is to be accelerated. I was anticipating the overall energy requirement.

I think we can have two cases:

1. conventional “moving wave packet” propagating in the outer space having no matter, energy, or information traveling faster than c;
2. forced “moving electrodynamic wave packet” along the array length, receiving enough flow of energy for keeping (v>>c) , in this case, we can have strongly forced energy moving along the array length faster than c, but if the array of dipoles moves to the opposite direction, then the whole conjunct will have nothing faster than c.

Before the “moving wave packet” propagating away from the array of dipoles, will the extra energy be converted into acceleration propelling the array of dipoles to the opposite direction?

Obs: In this case, the array of dipoles is floating in the deep space. Another case is the array fixed inside a container in which net propagation of energy to dipoles would be blocked by stationary waves. I think if the array is floating in the deep space, without stationary waves surrounding it, it will have facilitated the propagation of energy to dipoles.

 

[Dale]

The array of dipoles is that which have mass and is to be accelerated. I was anticipating the overall energy requirement.

I thought the dipoles were just generating the wave with phase velocity v>c. If the dipoles are being accelerated then what is doing the accelerating? Your setup is not very clear.

In any case, dipoles work according to Maxwell's equations so you will never get a group velocity >c or any material object traveling with v>c.

 

[Phrak]

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

It is defined in Infinitesimal Calculus.

...The infinitesimal calculus does a better job of making sense of Δy/Δx where Δx --> 0, than any other calculus of which I am aware.

 

[Phrak]

"Nothing travels at greater than the speed of light" is just street language. Ignore it.

There's plenty of stuff that locally propagates at great then c. In fact most stuff does have this greater-than-c attribute in various incarnations. What's the point of this, Cosmos; what is driving you?

I get the impression that you are dissatisfied with conventional wisdom in the claim that massive stuff must propagate at less than c. In fact, I think you take this as a challenge. This I like. Am I in error in any of this?

 

[Cosmos2001]

I thought the dipoles were just generating the wave with phase velocity v>c. If the dipoles are being accelerated then what is doing the accelerating? Your setup is not very clear.

In any case, dipoles work according to Maxwell's equations so you will never get a group velocity >c or any material object traveling with v>c.

I’m sorry; it is difficult to me to express it in a clearer form.
Now, I’m not trying to violate “nothing can move faster than light”; I’m trying to use it as support.

The energy in each dipole will never travel faster than c, but the overall energy moving along the array length will be forced (v>c), however, in the surrounding medium the speed is limited to c. To prevent speed violation; the array of dipoles will be forced to move to the opposite direction, doing (v=c), evicting energy flow faster than c.

If an object is traveling at low speed, vacuum doesn’t offer both support and resistance to change velocity. If the object is traveling close to c, it will offer resistance. The idea here is to take advantage of the resistance transforming it into support for initial acceleration of massive objects. Is it possible?

 

[epenguin]

I am surprised this thread reaches 4 pages without a mention of tachyons, particles with the remarkable properties: 1. Even I have heard of them 2. They can only travel faster than light - it takes infinite energy to slow them down to that speed. They achieve this remarkable property by their mass being an imaginary number.

Like all the most elite particles they are not actually known to exist. They seem to have been played with as an idea over the years. I suspect and would like to think this play is not entirely futile.

At the risk of being thought to have suffered an infantile regression, if they existed would we see them? Would they see us? Couldn't they exist in an incommunicado copresent parallel universe and mightn't they be worlds of positrons and antiprotons and this SOLVE THE PROBLEM OF BARYON NUMBER ASYMMETRY? Where do you get application forms for Nobel Prizes?:shy:

Anyway there is a Wikipedia article about them http://en.wikipedia.org/wiki/Tachyon - I found it quite difficult, but this one http://en.wikipedia.org/wiki/Tachyons_in_fiction was easier. It is based on the following fundamental principle: "it can impart a science-fictional "sound" even if the subject in question has no particular relation to superluminal travel (a form of technobabble, akin to positronic brain)."

 

[Dale]

The energy in each dipole will never travel faster than c, but the overall energy moving along the array length will be forced (v>c),

No, only the phase velocity will be >c. Energy does not move at the phase velocity.

however, in the surrounding medium the speed is limited to c. To prevent speed violation; the array of dipoles will be forced to move to the opposite direction, doing (v=c), evicting energy flow faster than c.

I don't know how you arrive at this conclusion. The array of dipoles won't move at all, dipole radiation is symmetric.

If an object is traveling at low speed, vacuum doesn’t offer both support and resistance to change velocity. If the object is traveling close to c, it will offer resistance. The idea here is to take advantage of the resistance transforming it into support for initial acceleration of massive objects. Is it possible?

Not even remotely. Lots of experiments have been done with phase velocities >c. The kind of propulsion you envision doesn't exist. There is no "traction" from phase velocities like you are supposing. In fact, there is no physical significance to phase velocities >c at all any more than there is a physical significance to the velocity of the "dot" from a laser pointer.

 

[Cosmos2001]

No, only the phase velocity will be >c. Energy does not move at the phase velocity.

I don't know how you arrive at this conclusion. The array of dipoles won't move at all, dipole radiation is symmetric.

Not even remotely. Lots of experiments have been done with phase velocities >c. The kind of propulsion you envision doesn't exist. There is no "traction" from phase velocities like you are supposing. In fact, there is no physical significance to phase velocities >c at all any more than there is a physical significance to the velocity of the "dot" from a laser pointer.

In a multiphasic linear motor, if (v<c), energy move at the phase velocity, it is hard to refute this; I think is a true fact for (v<c) because without this the linear motor would not work.
My hypothesis is, if (v>c), the energy will move forcedly at the phase velocity, facing relativistic resistance.

It is only a hypothesis.
Always seeing it as a multiphasic linear motor: if (v<c) then energy will flow along it in a non-forced way because it will not face relativistic resistance, energy will be dissipated into outgoing multiphasic waves increasing their amplitude. If (v>c) then energy will face relativistic resistance in order to be dissipated into the outgoing multiphasic waves, relativistic resistance will become a hypothetical relativistic support.

DaleSpam, I have no problem with you proving I’m wrong, if you can I’m grateful to you, but I felt I’m failing in describing my point of view.

Well, I know that “lots of experiments have been done with phase velocities >c”, but I’m not finding out one using an array of dipoles.
Please, could you give some clue to finding it?