travelling forward in time

[joe-90]

I guess that it's because light is Constant (as per the equation). If it varied under any circumstance it wouldn't be would it?

 

[sooey]

I guess that it's because light is Constant (as per the equation). If it varied under any circumstance it wouldn't be would it?

Don't know what that means joe, don't think you do either. I reckon you're as thick as I am.

 

[joe-90]

I'm brighter than you think.

 

[sooey]

I think you're a pretty intelligent guy Joseph. But you've got to have a different way of thinking to get your head round some of this physics stuff.
I can't, and I don't think that too many others can either.

 

[gregers]

if your travelling at the speed of light in a car and turn the headlights on will they shine up in front of you?or will you still be in the dark like i am

 

[joinerjohn]

But,,,,,,,,,,, just to throw a spanner in the works,,, The speed of light isn't constant. When it enters another medium, such as glass or water or even air., it is slowed down. Hence the principal of refraction. It's also bent by strong gravitational fields, therefore light is affected by external influences and so cannot be constant.

 

[Monkeh]

The speed of light in a vacuum is a constant.

 

[Mickymoody]

The speed of light in a vacuum is a constant.

If the Universe is constantly expanding, then is that correct? If you are travelling towards the outer edge of the Universe, or travelling in from the outer edge of the Universe?

Bloody slow speed of light! There is so much to discover. Just imagine the wonder when electricity, in a useable form was found, Oh we have this stuff, it hurts if you touch it, what next? Then someone got some acid,and paper, and sand, and crystals, oh we have a radio/telephone/telegraph...what next? And that's what? in the last 200 years? How many advances since then?

Just been on the news that an earth like, planet has been detected, but due to a technical failure on pulse rocket motors, being millions of light years away, not able to confirm for many years, until technology catches up.

 

[libby lou lou]

how many people have seen "visitors* from the past or the future? if time travel was valid, moses would of told adam, what would eve think

 

[Mickymoody]

how many people have seen "visitors* from the past or the future? if time travel was valid, moses would of told adam, what would eve think

Lay off the Apples, love, just cause a speaking snake told you, don't mean you have to love, now give me a rib.

Moses, lay off the curries, weather will part the seas. Jesus - lay off on the sidestall, a couple of fish, and some bread, at THOSE PRICES!!!! Get real! KFC is selling them at half the price down the track!

I watched a film the other day, where a talking bear was adopted by a human family, he discovered that it wasn't his family, despite the obvious differences from himself, to humans, maybe a race point there, all are equal. So bear set up in a commune of other 'talking bears', to re-annact Blues brothers, type scenario, set up the best music group in the world...and went on to win their community centre back from the evil, Christopher Walken..that was intend on destruction, and retribution..

There were actually several cameo appearences, so more like a Disney propaganda film, than a real attempt at a film, what was it called? You gotta watch it!

So, if Eve, is talking to snakes, then Disney is the new mesiah! Didn't Walt, have nefarious collusions with people he shouldn't?

 

[joe-90]

The speed of light in a vacuum is a constant.

That Dyson geezer knows a trick or two.

 

[Space cat]

The speed of light isn't constant. When it enters another medium, such as glass or water or even air., it is slowed down.

This is true. The speed of light is given by

v = 1 / sqrt(mu x epsilon)

where mu and epsilon are the permeability and permittivity of the medium.

Now I don't know of any medium whose permittivity is less than that of a vacuum but there are magnetic materials whose permeability is less. This suggests that it might be possible to make something in which light can travel faster than it does in a vacuum. But I doubt it. There is probably some law linking the two properties so that such a material cannot exist.

It's also bent by strong gravitational fields

This is also true. Moreover, light has momentum and so it must pull back on the mass that deflects it (Newton's third law). Unless we want to throw the law of conservation of momentum out the window, the inevitable conclusion is that light possesses gravity.

Question: Is it possible for a light wave to generate sufficient gravity to contain itself within a microscopic black hole? (Since we have three space dimensions, I would guess that there would be three waves in there). It should be possible to work this out from the theory of general relativity - which I never studied. I'll get round to it some day.

 

[joinerjohn]

Just to confuse the issue even more,,, IS light a wave? as in a light wave or is it a particle? as in a photon (one unit of light).
Discuss

 

[0000]

The wave like property of light is due to its quantum nature. Photons are particles.

I think there is a little confusion. The train idea is precisely about that fact that as you approach the speed of light, time for the passengers must slow down as as to no violate the not faster than the speed of light law.

However some might see that law as producing a paradox as in the wormhole problem. However they way they suspect it isn't is they are able to prolong the life of particles that would otherwise never exceed a certain amount of time. However unless they figure out exactly what is happening, it might not work scaled up.

 

[Space cat]

IS light a wave? as in a light wave or is it a particle?

Or is it something completely different?

I don't entirely believe in photons. They're a useful concept because electromagnetic energy does seem to come in discrete lumps - but if they're particles then they're very strange ones. What other particle comes in an infinite range of sizes?

The photon theory also runs into terrible trouble as the frequency falls to zero. At very low frequencies - and I mean something like one cycle per day - your wave must be made up of vast numbers of these hypothetical photons, each carrying virtually no energy. If the wave slows down to nothing, you're stuffed!

I have a tentative idea that maybe waves really are waves but our emitters and detectors, being made of particles, can only create or absorb wave energy in discrete lumps.