What happens to light after it leaves its source?

Question

Why is it dark at night with all of the universe's stars light beaming out?

Answer 1

light is (in a nutshell) waves of energy. Waves (in general) travel in a straight line. stars are so far away that not much of their energy or waves hit the planet.

Answer 2

Not to worry, there is nothing wrong with physics. All the stars in the uiverse are going, so it is never truly dark! However, there are things that create apparent blackness. There is a lot of gas and dust just chillin' out between the stars, and that absorbs a lot of the light. There is also the wall at the beginning of the universe.

The further you look away in space, the further back in time you look. The andromeda galaxy is 2.9 million light-years away. Therefore, the light we see from that galaxy left 2.9 million years ago. Our ancestors were running naked on the plains of Africa when the light we now see left that place. If you looked at a galaxy that was even further away, the image would be even further back in time relative to Earth.

However, if you look further and further away you eventually are looking back into the Big Bang itself at about 13.7 billion lightyears. You can't watch the actual flash because the explosion produced a hazy cloud of ionized hydrogem gas. If you look back too far, all you see is this darkness. There is also the light from the lifting of this fog, which is quite possibly the oldest light in the universe. Unforunately, this light is rather faint by the time it reaches us in the far future of the universe and it has been redshifted into the microwave frequencies that human eyes don't see so we see nothing but black in empty space. They built a machine that can take pictures of it anyway:

http://map.gsfc.nasa.gov/m_uni/uni_101Flucts.html

Answer 3

Because of two things:
first, light from a point source (like a far-away star) obeys the inverse-square law: as the light spreads out in all directions, the intensity of the light measured in any one direction is 1/4th as strong when you're twice as far away, 1/16th as strong when you're four times further away, etc. That's not because the light "loses energy" or anything, it's because the light spreads out, so a smaller percentage of what was emitted goes in any one direction as you move further away.
Second, space is far from empty -- there is an awful lot of gas, dust, and other particles even in "empty" space, which absorbs, reflects (away from your point of view) and bends light. That further reduces the amount of light that can travel great distances.

The expansion of the universe also has some effect, since the further an object is away from us, the faster it's moving away from us -- shifting the light frequencies towards the red and putting more "space" between you and the light so the dust and inverse square laws can act on it.

Only a fraction of the light from all of the universe's stars (or for that matter, just the stars in our own galaxy) ever hits the earth -- the light goes off in all directions, and is dimmed by dust and gas. That tiny fraction that comes our way we see as starlight -- the rest is dark.

Answer 4

light travels in waves and in a straight line. It bounces off an object!! the stars shine at night because the sun or any light source is hitting the star or for an example the light in your room it illuminates the room and makes shadows from what it hit!!!
WOOT , i am smart and learned this in 7th grade except the part about the stars!!

Answer 5

Hi. It travels in a line (or a curve if there is a gravity field) until it hits something which absorbs it. The stars are bright enough that with a night vision scope you can see quite well.

Answer 6

It goes out, LOL!
It goes to the other side of the earth.........