# Some things can reach the speed of light and some can't

Discussion in 'Physics & Math' started by S. Dalal, Apr 6, 2002.

1. ### S. DalalMathamatics is my lifeRegistered Senior Member

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35
In theory any thing that contains any type of mass can and will not ever reach the speed of light, this is due to the enormous amount of energy that one would be creating, if anything with a mass were to reach the speed of light instantly their mass would be equal to 0, as something starts to reach the speed of light the atoms that make up the mass start to "un bond" if you will and then the atoms sporate and scatter into space.

Yet, it is known as a fact that a photon (subatomic particle that light is constructed of) does indeed have a mass, this is proven by when light is passed by a black hole it is sucked in, therofore a photon does have mass, and there have been expericments that have generated photons past the speed of light (300,000 km/s), so what does this mean, could Enstine be wrong? E=mc^2 states that any mass would need infinite time to reach the speed of light, yet if a photon has a mass, and it has reached faster than the speed of light one would assume that Enstine is WRONG, but you know what they say about assuming.

3. ### GRO$$Registered Senior Member Messages: 304 "there have been expericments that have generated photons past the speed of light" no there havent... Please Register or Log in to view the hidden image! Einstein was smart guy I think... not my place to prove or disprove his theories right now, with the amount of knowlege I currently have... I hope to once fully understand what he did... 4. ### Google AdSenseGuest Advertisement to hide all adverts. 5. ### John Devers(AVATAR)Registered Senior Member Messages: 120 First Black holes don't suck any more than our sun sucks, according to GR the spacetime is bent around them, light travels a straight path in its own frame of reference. Second it is not the photon that travels faster than light, you can't get a whole photon to do that. It is only the propogation wave front of the photon's wave function that travels faster than c. 6. ### Google AdSenseGuest Advertisement to hide all adverts. 7. ### (Q)Encephaloid MartiniValued Senior Member Messages: 20,834 if anything with a mass were to reach the speed of light instantly their mass would be equal to 0 Mass actually increases as it approaches the speed of light. as something starts to reach the speed of light the atoms that make up the mass start to "un bond" if you will and then the atoms sporate and scatter into space. Mass reaches infinity near the speed of light. The energy required to accelerate mass to the speed of light becomes infinite. Therefore, it is impossible to reach the speed of light. Yet, it is known as a fact that a photon (subatomic particle that light is constructed of)... What particle are you referring? ...does indeed have a mass, this is proven by when light is passed by a black hole it is sucked in, therofore a photon does have mass A very rational conclusion, genius. Please Register or Log in to view the hidden image! *photons have no mass* and there have been expericments that have generated photons past the speed of light (300,000 km/s) What experiments? so what does this mean Irrational delusion on your part? could Enstine be wrong? Possibly, I don't know of an Enstine. Einstein, however was right. E=mc^2 states that any mass would need infinite time to reach the speed of light No. It states that there is an equivalence between mass and energy. yet if a photon has a mass, and it has reached faster than the speed of light one would assume that Enstine is WRONG but you know what they say about assuming. Yes, IF a photon had a mass and IF it accelerated faster than the speed of light, both Enstine and Einstein would be wrong. But it doesn't and it won't, so it appears you're wrong. No assumptions required. Please Register or Log in to view the hidden image! 8. ### tetraHelloRegistered Senior Member Messages: 144 Both are true. A lil' calculus will set you two straight Please Register or Log in to view the hidden image! y=mass x=speed o' light lim(y -> x)=0, and there is an asymtope on the graph of this. Kinda like the tangent curve. As you approach x, y will approach infinity. When you get to x, y is undefined, but would start off at zero at any distance from x. I'm not saying you can actually reach x, just that once you reach it y approach zero as a start. Last edited: Apr 6, 2002 9. ### c'est moiall is energy and entropyRegistered Senior Member Messages: 583 All has been answered, just some remarks: Photons are said to have a *relativistic* mass -> what does this actually mean? A "fake" mass? (you gotta put everything equal to 0 in the equations if you gonna count in this "mass" so it's quite useless no?) Some experiments related to universities did break the lightspeed barrier, no? I thought I read about this some time ago. What these scientists said, however, was that Relativity was in no way broken cause the "information" was not carried at that speed, hence Einstein was still right. -> someone here might know some sources of these experiments: who, where, when -> what is meant with this "information" -> how is this information related to Special Relativity 10. ### Adam§Þ@ç€ MØnk€¥Registered Senior Member Messages: 7,415 Maybe he was referring to Lijun Wang's experiment, and that one involving microwaves that I can never find any links for. *shrug* I don't know. http://www.neci.nec.com/homepages/lwan/ Have there been any problems with Wang's data? Was it bollocks, or did he do as early reports suggested? Anyway, on to theory. It seems to me that the speed of light is always less than the constant C. Why? Coz it's always passing through stuff that diminishes that constant. Since that less-than-C speed is the only real speed of light, and since light in that situation has been slowed to ridiculously low speeds in many experiments, wouldn't that mean things can travel faster than light? I've never even heard of light travelling at the constant C. Only less than C. So, if something can be made to move faster than that reduced rate...? This is not a statement, just a question. 11. ### (Q)Encephaloid MartiniValued Senior Member Messages: 20,834 Have there been any problems with Wang's data? Was it bollocks, or did he do as early reports suggested? It was bollocks. NEC later sent out a press release apologizing for the errors. They were immensely embarrassed. 12. ### (Q)Encephaloid MartiniValued Senior Member Messages: 20,834 Both are true. A lil' calculus will set you two straight m = m0 / square root 1 - (v/c)^2 When an object obtains the speed of light, the value of v/c becomes 1 and the denominator of the fraction becomes zero. But having a denominator of zero is undefined, or not possible. note to Q - get subscript html. 13. ### (Q)Encephaloid MartiniValued Senior Member Messages: 20,834 Photons are said to have a *relativistic* mass -> what does this actually mean? "Relativistic mass" is rather a redundant term but basically can be understood to mean energy. The relativistic mass of a photon, for example, is frequency dependent. UV photons are more energetic than visible photons. Mass is usually described as 'invariant mass' or 'rest mass.' 14. ### GRO$$Registered Senior Member

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lim(y -> x)=0, and there is an asymtope on the graph of this. Kinda like the tangent curve.

dosent light reach the speed of light tho? and if it has mass... which is what i believe right now, that mass travels at a speed which is on that asymptote, no? :bugeye:

15. ### GRORegistered Senior Member

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304
okok, maybe it dosent have mass after all...

16. ### thedIT GopherRegistered Senior Member

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1,105

That much is true.

No. You simply can't reach light speed. This has been proven countless times in particle accelerators

This is simply wrong.

No it does not. A photon is the quatum mechanical analog of a particle. This due to wave/particle duality.

17. ### c'est moiall is energy and entropyRegistered Senior Member

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583
from that website:

"Information coded using a light pulse cannot be transmitted faster than c using this effect. Hence, it is still true to say that "Information carried by a light pulse cannot be transmitted faster than c." "

that's what i meant with the information
but since Q tells us that the Wang guy was wrong it doesn't matter anymore (why doesn't he say so on his website??)

18. ### thedIT GopherRegistered Senior Member

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1,105
it's me

Ego, otherwise!

19. ### C-man87Registered Member

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3
We must be able to trave at the speed of light

People say that when you approach the speed of light your atomic bonds will break and you will scatter across space. But why is traveling at the speed of light any different than traveling at other finite speeds. Although it is faster, it should still obay the basic laws of physics. For example, when we broke the sound barier, we didn't turn into sound waves. I think that because light traveled faster than any known force, Einstein thought that if we were to travel at that speed we must become light, but our speed should not affect anything. When we travel at that constant finite speed, we should be able to walk around in the space craft and resume normal functions.

20. ### StryderKeeper of "good" ideas.Valued Senior Member

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13,104
I remember looking at some information on a "Timelords" archive somewhere in the back and beyond of the BBC website.

http://www.bbc.co.uk/science/horizon/timelord.shtml

The Speed of Light was transversed at 4.7 Times the speed, in fact Mozart symphony was conveyed across a laboratory.

Now I'm sure that it was heard within pica seconds (or would be heard if at a lower frequency) of it being played.

Another source:
http://www.aei-potsdam.mpg.de/~mpoessel/Physik/FTL/tunnelingftl.html

21. ### James RJust this guy, you know?Staff Member

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35,532
The question of whether light has mass is addressed in detail in the "Does light have mass?" thread.

(Q):

You are incorrect about the Wang experiment. It did observe a pulse of light moving faster than c. Nothing in physics prevents that from occurring, and Wang explicitly made the point in his paper that his experiment did not violate relativity.

Many other experiments have duplicated Wang's results, including some recent ones done by a colleague of mine.

22. ### CrispGone 4everRegistered Senior Member

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1,339
Wang's paper

Hi James R,

Impressive. This surely is a very very very nice demonstration of the wave-nature of light. I must admit that I never really was impressed by Young's experiment, but this one surely makes up for that

.

Bye!

Crisp

23. ### c'est moiall is energy and entropyRegistered Senior Member

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583
Explain why the experiment is in agreement with relativity. What information are we talking about.