how fast does light think light travels?(physics question)

[mietla]

Originally posted by MrCoffee
Why does the intensity of light dissipate with distance?

because it is emitted radially (or at least has a radial component). As a result the photons emitted at the particular time interval have to "cover" more spherical surface.

Since light intensity is nothing more than a density of photons, the intensity of the light beam goes down.

Laser light which produces a light bean by far more parallel any any other source, will diverge slower, but still, it will diverge and lose intensity with distance.

[AKS\/\/ulfe]

Time is an invention of humanity, as is everything else we know.

Therefore, using time, or anything else, to explain anything only explains things by what we know and not what by how it all works.

The answer to everything lay in booze.
-SW

[Nash]

hehe

[lasersailor184]

Udie, I thought that happened because the forces on the clock slowed it down in some parts.



However, time is an imaginary measurement, just like feet, meters, inches.  You can't actually hold a meter.  You can hold a meter stick which tells you how long it is.  The same with time.  Time doesn't actually exist.  It's just a constant imaginary measurement.

[Manedew]

assume for a second you could travel faster than light .....

you'd be able to see yourself before you left.... once you stoped ...

it would stand to reason, that while in trasit at faster than light speeds, everything behind you should be dark

[lasersailor184]

But if you look forward, you'd see what has happened because you're intercepting leaving light waves.

[Udie]

Originally posted by lasersailor184
Udie, I thought that happened because the forces on the clock slowed it down in some parts.



However, time is an imaginary measurement, just like feet, meters, inches.  You can't actually hold a meter.  You can hold a meter stick which tells you how long it is.  The same with time.  Time doesn't actually exist.  It's just a constant imaginary measurement.

 honestly I don't have a complete understanding of it.  Gravity affects time also. I listen to Steven Hawking's " A brief history of time" a couple of times a week. I have an mp3 of it.  But it cuts out right in the middle of the black hole part of the book which deals with this.  The basic gist of it though is that time and space are both relative.  Here's an example from the book about space being relative....

   You have a guy on a train moving down the tracks.  He bounces a ball on the floor of the train and then catches it.  To him the ball went straight down and straight back up.  But to an observer on the ground the ball traveled a 100 feet before it hit the ground and then another 100 feet before the guy caught it.  

 I have a better understanding of space relativity than time relativity, that one blows the mind.  But in the book he talks about how they've proved the theory (that clock example above is one proof)  Evidently it's a measurable effect and a constant with relation to speed.  The faster to the speed of light the slower your time relative to an object that is slower.  Relativity is the key I think.  To the person going the speed of light nothing would be diferent WRT time.

 Nothing with mass can go the speed of light though.  The book says that the faster an object goes the more it's mass increases (don't ask me why!!!) thus requiring more energy to make it increase in speed even more.  By the time the object is close to the speed of light it's mass is so large that it would take an infinite amount of energy to make it accelerate to the speed of light.  Photons don't have mass right?  They're just packets of energy right?  And please don't go into the particle vs. wave thing, that one really give me a brain ache!

[Samiam]

Originally posted by mietla

Just think of it, some quasar emits a photon 10 billions years ago, "knowing" that you'll be born 10 billion years later to see (absorb it with a particle in your eye).

Man, daylight savings time must really screw with their little photon brains.

[101ABN]

The speed of light in vacuum is exactly 299,792,458 m/s (metres per second)

wow, look at the big brain on ken. ha ha

The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

damn, im starting to shake....good coffee

When people refer to the speed of light, they refer to the definition above - the speed of light in a vacuum.

The speed of light is normally rounded to 300 000 kilometers per second or 186 000 miles per second.

The speed of light depends on the material that the light moves through - for example: light moves slower in water, glass and through the atmosphere than in a vacuum. The ratio whereby light is slowed down is called the refractive index of that medium.

In general, the difference in the speed of light in other mediums is ignored.

[mietla]

Originally posted by AKS\/\/ulfe
The answer to everything lay in booze.
-SW

A excellent analogy. Both booze and time can go backwards, and if you read about lives of the scientist, many of them used booze as a medium for deeper understanding of time.
Just like time slows down with acceleration, so it does with alcohol level.

Einsten has proven that force generated by acceleration and forces generated by gravity are indistinguishable. He united gravity with Newtonian dynamics, so to speak.

The humanity still waits for a genius, who will prove that time slowing while drinking (or stopping while you passed out) is it fact the same phenomenon, and that passing out is in fact equivalent to travel at light speed.

The fact that you usually do not remember anything in a morning, and the fact that women who looked young last night, suddenly aged by the morning is a very strong indication that the theory is correct, but we need a proof.

[mietla]

At the very, very  least 80 proof. Preferably more.

[NUTTZ]

Originally posted by Manedew
assume for a second you could travel faster than light .....

you'd be able to see yourself before you left.... once you stoped ...

it would stand to reason, that while in trasit at faster than light speeds, everything behind you should be dark

Then traveling at the speed of light with a flashlight in your hand would be a moot point. Could you shine it backwards to see where you been???? Or would that be some sort of Physic masturbation??


NUTTZ

[Sixpence]

As I get older, times seems to go faster. It seems the time period between 1975 and 1985 took a very long time. The years 85-95 seemed to go by a little quicker, and 95-present seems to have gone by in the blink of an eye. Am I accelerating or decelerating? OW! *brain to sixpence* what the hell are you reading?

[Adogg]

Originally posted by Otto
If they traveled at the speed of light (impossiable) time would stop for them.  They would only age during the time they were at their destination.  Not on the outward or return trip.

...course we're all talking out of our tulips here since none of us have taken our spits into dives in the quest to breech c (speed of light).

But if a journey to Alpha Centauri takes four light years the crew would age (relative to themselves 4 years.) Now what that translates to in earth years I don't know.

Someone correct me please.

[AKIron]

Time does seem to go faster as you get older. I think it's a matter of perspective. When you're ten, a year is one tenth of your life, When you're 50, a year is only one fiftieth.