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| medlakeguy |
 Posted: Sat May 10, 2008 10:23 pm Post subject: couple questions about light |
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Joined: 22 Feb 2008
Posts: 123
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as i understand it you cant accelerate an object past the speed of light because its mass increases as it approaches c, but light has no mass so why does it have a limit on its speed?
another probably dumb question but theres no limit as to how long of a wavelength light can have so would faster than light communication be possible by just aiming the top of a very large light wave at something distant? (hope that made sense) |
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| raed |
| Posted: Sun May 11, 2008 1:20 am Post subject: Re: couple questions about light |
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Forum Freshman
Joined: 05 May 2008
Posts: 55
Location: Cairo
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| medlakeguy wrote: |
| another probably dumb question but theres no limit as to how long of a wavelength light can have so would faster than light communication be possible by just aiming the top of a very large light wave at something distant? (hope that made sense) |
I think if wavelength becomes larger than 700 nm it will be not light ! 
But if u mean generally electromagnetic waves , radio waves have large wave lengths to be used in communications.
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Raed Ahmed Çeleby
Dont let MEDIA affect you , You have a brain !
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| anand_kapadia |
| Posted: Sun May 11, 2008 1:34 am Post subject: |
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Joined: 16 May 2006
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Location: India
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hope u know about conversion of energy into mass...
These electromagnetic waves convert into mass |
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| Dishmaster |
| Posted: Sun May 11, 2008 2:58 am Post subject: Re: couple questions about light |
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Joined: 30 Apr 2008
Posts: 313
Location: Heidelberg, Germany
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| medlakeguy wrote: |
| as i understand it you cant accelerate an object past the speed of light because its mass increases as it approaches c, but light has no mass so why does it have a limit on its speed? |
Well, this is a somewhat simplistic view. It SEEMS that its mass increases to infinity. Really, it does not. In fact, you have to analyse the relativistic impulse or kinetic energy of a particle. Classically spoken, the impulse is the product of the mass and the velocity. With relativity, it is a bit different, because you need an additional factor including the speed of light.
This factor is negligible for very low speeds giving again the classical expression. For velocities close to the speed of light, the impulse reaches infinity. Now, you can separate the relativistic equation in such a way that you only have the classical velocity and another factor containing the mass and the relativistic modification.
In popular demonstrations, this often called the relativistic mass, but it is actually wrong. It is more or less just a mathematical trick. Still, the equation for the impulse tells you that no particle can reach the speed of light. If this was the case, it would contradict the basic physical principles of conservation of impulse and energy. You would need an infinite amount of energy in the universe. |
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| SuperNatendo |
| Posted: Sun May 11, 2008 7:07 am Post subject: |
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Forum Masters Degree
Joined: 10 Dec 2007
Posts: 518
Location: Nashville, TN USA
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light does, in fact, have mass and takes up space.
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Last edited by SuperNatendo on Sun May 11, 2008 2:01 pm; edited 2 times in total |
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| (Q) |
| Posted: Sun May 11, 2008 8:11 am Post subject: Re: couple questions about light |
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Forum Professor
Joined: 12 May 2005
Posts: 1594
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| medlakeguy wrote: |
| as i understand it you cant accelerate an object past the speed of light because its mass increases as it approaches c, but light has no mass so why does it have a limit on its speed? |
The "limit" placed on how fast light can travel is based on the properties of space and not the light itself.
| Quote: |
| another probably dumb question but theres no limit as to how long of a wavelength light can have so would faster than light communication be possible by just aiming the top of a very large light wave at something distant? (hope that made sense) |
Not really. Again, the light can travel only as fast as the properties of the space it travels through allows.
The permittivity of free space is how space affects the forces between two charges while the permeability of free space is the proportional induction and intensity of magnetic fields, or the ratio between magnetic displacement and magnetic field strength. |
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| William McCormick |
| Posted: Sun May 11, 2008 11:57 am Post subject: Re: couple questions about light |
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Forum Professor
Joined: 03 Apr 2008
Posts: 1301
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| Dishmaster wrote: |
| medlakeguy wrote: |
| as i understand it you cant accelerate an object past the speed of light because its mass increases as it approaches c, but light has no mass so why does it have a limit on its speed? |
Well, this is a somewhat simplistic view. It SEEMS that its mass increases to infinity. Really, it does not. In fact, you have to analyse the relativistic impulse or kinetic energy of a particle. Classically spoken, the impulse is the product of the mass and the velocity. With relativity, it is a bit different, because you need an additional factor including the speed of light.
This factor is negligible for very low speeds giving again the classical expression. For velocities close to the speed of light, the impulse reaches infinity. Now, you can separate the relativistic equation in such a way that you only have the classical velocity and another factor containing the mass and the relativistic modification.
In popular demonstrations, this often called the relativistic mass, but it is actually wrong. It is more or less just a mathematical trick. Still, the equation for the impulse tells you that no particle can reach the speed of light. If this was the case, it would contradict the basic physical principles of conservation of impulse and energy. You would need an infinite amount of energy in the universe. |
The speed of radio being faster then 186,000 miles a second, was dis proven during the Apollo missions. It was already dis proven long before. However there were no tests considered conclusive enough here on earth. To change Newtons idea of velocity of light. Things work without knowing what it is.
And we were never given a voice to show off how we could easily prove that radio is faster then light. If only upon start up of the beam of light.
Radio was shown to be instantaneous from a distance a few miles from the moon and back to earth.
The astronauts that were under orders to follow the rules of communication aboard the space craft during live broadcasts, already knew this. They had to sign papers guarding the missions secrets. The Freedom of information act was just an act that came to late and had no real purpose.
The astronauts had no way to show or prove the speed of radio. Until someone on the ground fifteen minutes after the astronauts left lunar orbit, got a hold of the ground microphone during a live broadcast. From an armed guard at Houston control.
The two guys who new each other, first joked about how he got the microphone from the guard. And the fellow on the ground said, "That the big guy with gun said when fifteen or twenty minutes are up my duty is over" do what you want to do after that.
They both laughed with joy, and during this conversation there was no annoying communication lag. They were just talking like on walkie talkies. One of the other astronauts said, you better watch the mandatory radio delay. He just laughed.
The fellow on the ground said "you up to some fast radio turn around". And the fellow in the capsule said "you bet yea". They did four cycles of communication in under two seconds. Earth to the space capsule twice, and twice from the space capsule to earth.
Things like this misunderstood by some, have lead people mis-educated by college to believe that the mission was a hoax and was actually being broadcast from earth.
So believe what you have to believe to make it through the day. But if you ever want more it is all there. Ready to go.
Sincerely,
William McCormick
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Warning: Any information contained in this post could be part of a conspiracy to make you stupid. So only use it if you understand it. Use at your own risk.
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| William McCormick |
| Posted: Sun May 11, 2008 12:06 pm Post subject: |
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Joined: 03 Apr 2008
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| SuperNatendo wrote: |
| light does, in fact, have mass and takes up space. |
Light has no mass. Light is electrons, so when it is beamed through something it does excite the atoms to some extent. It cuts a path through air and thins the air.
Whenever you slow natural ambient radiation down. The electrons will be in one spot longer then if they were going fast. This causes an effect.
It is the only effect in the universe.
Cutting a path is what takes some time. Once cut, light transmits instantaneously.
Sincerely,
William McCormick
_________________
Warning: Any information contained in this post could be part of a conspiracy to make you stupid. So only use it if you understand it. Use at your own risk.
http://www.Rockwelder.com |
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| (Q) |
| Posted: Sun May 11, 2008 12:28 pm Post subject: Re: couple questions about light |
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Forum Professor
Joined: 12 May 2005
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| William McCormick wrote: |
Radio was shown to be instantaneous from a distance a few miles from the moon and back to earth. |
No Billy, it was not instantaneous. |
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| (Q) |
| Posted: Sun May 11, 2008 12:31 pm Post subject: |
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Forum Professor
Joined: 12 May 2005
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| William McCormick wrote: |
[
Cutting a path is what takes some time. Once cut, light transmits instantaneously. |
Did light cut a path straight through beyond your retinas when you stared at the sun? |
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| Tenacity |
| Posted: Sun May 11, 2008 1:10 pm Post subject: |
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Forum Sophomore
Joined: 10 May 2008
Posts: 100
Location: Instow, Devon, UK
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| William McCormick wrote: |
Light has no mass. Light is electrons, |
Contradiction of the century. Wait I'm pretty sure some religious person may have beaten you to it.
Electrons have a mass of roughly 1/1850 of a nucleon. So you're saying that light has no mass? Also we know that a mass travelling at light speed (to the observer) has infinite mass. Oh no you blew something up again Will...
Please either read a common science book or get out of the field. You're clearly not quite getting it.
Last edited by Tenacity on Sun May 11, 2008 4:07 pm; edited 1 time in total |
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| SuperNatendo |
| Posted: Sun May 11, 2008 2:01 pm Post subject: |
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Forum Masters Degree
Joined: 10 Dec 2007
Posts: 518
Location: Nashville, TN USA
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Here is the predicament, if light doesn't have mass, then how is it sucked into the gravity well of a black hole, the problem is billy thinks black holes are just planets.
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| Tenacity |
| Posted: Sun May 11, 2008 3:50 pm Post subject: |
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Joined: 10 May 2008
Posts: 100
Location: Instow, Devon, UK
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Ok I'll take a stab at explaining it. I haven't seen this written anywhere before so I'll tell you I'm making it all up right now but maybe it'll shed some light on it? 
If we utilise string theory that the absolute fundamental particle is infact a band of energy (string) which vibrates at different frequencies to produce quarks and other such building blocks, then we can closer understand the links with Wave Particle duality. It has been suggested (infact proved) that electromagnetic waves do, under various circumstances act as, particles.
If string theory is correct then matter is energy, this we already know as matter can be converted to energy and , theoretically, energy to matter. Somewhere here they must share a common bond. The problem could well be the current definition of gravity or explanations that masses attract one another.
If energy and matter are a'kin what is to say that gravity cannot exert itself on both? We already know that electromagnetic waves are manipulated by gravitational pull and that mass can be affected by magnetism (the floating ball experiment?).
Any additions and criticisms are, as usual, completely welcome. Apart from Will's because I don't like the idea that Ambient radiation has to thin out the air for light to travel instantaneously between points (why does it take 8 minutes to get from the sun to earth then?) as he's obviously going to infect us with his crazy. |
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| Dishmaster |
| Posted: Sun May 11, 2008 4:14 pm Post subject: Re: couple questions about light |
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Forum Senior
Joined: 30 Apr 2008
Posts: 313
Location: Heidelberg, Germany
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| William McCormick wrote: |
Radio was shown to be instantaneous from a distance a few miles from the moon and back to earth. |
It is getting funnier with every post. Hilarious! It might have been a very short delay, because the 384000km from the moon only take little more than a second. Did you know that the astronauts put a mirror on the moon that allows us to measure the exact distance of the moon with a laser? If the travelling speed would be infinite, the distance measured would be zero.
All other space missions farther out (e.g. Mars) always have to take this time delay into account. Have you watched the landing of the first Mars rover? Then you might have learned that the signals take several minutes to get to earth. This is the reason, why it had to move automatically. Remote control just does not work.
I will not comment on the ridiculous suggestion that the lag was just made up. |
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| Dishmaster |
| Posted: Sun May 11, 2008 4:20 pm Post subject: |
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Forum Senior
Joined: 30 Apr 2008
Posts: 313
Location: Heidelberg, Germany
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| SuperNatendo wrote: |
| Here is the predicament, if light doesn't have mass, then how is it sucked into the gravity well of a black hole, the problem is billy thinks black holes are just planets. |
Indeed, this is a problem that was solved by General Relativity. In this picture, mass does not produce a force, it just bends spacetime. Since photons without interaction with a medium (scattering, refraction, etc.) always travel on a straight line, they just follow the bent spacetime fabric. This has been shown with the positional shift of stars close to the line of sight towards the sun during solar eclipses or so-called Einstein rings due to gravitational lensing. |
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