Would the power of the light source matter? Example, a flashlight compared to a laser?
2006-10-03 06:23:28 · 6 answers · asked by jerry c 1 in Science & Mathematics ➔ Physics
186,000 miles per second, regardless of the source.
2006-10-03 06:25:24 · answer #1 · answered by JaMoke 4 · 0⤊ 1⤋
this would be a situation where the inverse square law would be applied, if the flashlight beam had one half of its initial intensity at 50 feet then it would have 1/4 of its initial intensity at 100 feet and so on and so on. There is no point where it would reach zero, theoretically. However, the laser would spread to some extent the same as the light but since it starts out as in phase coherent waves it would remain more concentrated than the light. Look at the lasers that we fire at the moon from Arizona, they hit the reflecting boxes left by the astronauts and bounce back directly to the earth, but the area they cover on the moon is much larger than the source on earth. I'm sure that some of this diffusion is caused on its path through the earths atmosphere. I would like to know if they have ever fired a laser at those reflectors from the space shuttle which would be outside the vast majority of the earths atmosphere. Maybe nasa has that answer.
remember 186,000 miles per second isn't just a good idea, it's the law.
2006-10-03 06:43:17 · answer #2 · answered by Douglas D 1 · 0⤊ 0⤋
The observable universe stretches about 13 billion light years from the big bang source of our universe to where we are observing effects (stars and galaxies) that far away from us in both space and time. One light-year is the distance a photon of light will travel in a vacuum in one year. That works out to be about 6 trillion miles per light year.
So the beams of light we are seeing back towards the big bang have traveled about 13 billion light years X 6 trillion miles/light year = 78 billion trillion miles to enter our telescopes. Can you imagine the frequent flyer miles we'd get on that many miles?
2006-10-03 06:46:43 · answer #3 · answered by oldprof 7 · 0⤊ 0⤋
Infinity at approximately 300,00 km/sec. That's how the hubble is able to "look back in time." at the early universe.
2006-10-03 06:31:58 · answer #4 · answered by ericnifromnm081970 3 · 0⤊ 0⤋
If there are no objects to block the path (including friction), it would continue on forever.
2006-10-03 06:25:35 · answer #5 · answered by trigam41 4 · 0⤊ 1⤋
No one hear actually knows the answer.
Perhaps forever, perhaps not.
If it got sucked into a black hole it would stop....unless it came out somewhere else.
2006-10-03 06:31:45 · answer #6 · answered by Anonymous · 0⤊ 2⤋