why does light travel in a straight line?

Answer 1

It doesn't. It travels in the 'shortest' distance between two points, in a 4-dimensionsl sense. Thus, in the vicinity of a mass large enough to cause a noticeable dilation of spacetime, it actually apears to travel in a curve.

Doug

Answer 2

Newton's first law of planetary motion states that:
A body remains at rest or moves along a straight line with constant velocity as long as no external force acts on it.
Einstein proved that although energy, including light, does not apply to the same rules as normal mass, it still has mass.
In order for anything to move in any way other than a straight line something has to interfere with the object in motion.
Light does not always travel in a straight line, light is constantly being reflected. Example, if you were to stand behind a large wall between you and a large enough light source, you would still be able to see around you because the light is reflecting off of every thing around you. But, if you were to stand within a sealed brick room with no light source inside, you would have no light to see.
This is because light is constantly reflecting off of everything around you, walls, leaves, grass, ect.
Another way to to show that light does not always travel in a straight line is to observe the bending of light around emense gravitational forces, as in planets. The gravitational force of a planet, or even better, a star, is great enough to bend light in a curve, as was discovered be Einstein. A black hole has a large enough gravitational force to actually suck in light to the point that nothing escapes.
To sum up, Light is just like any other mass, it will travel in a straight line unless something forces it to do otherwise.
Inertia.
I tried to keep this simple, hope it helps.

Answer 3

light does not always travel in a straight line. planets like the earth can bend the way light travels, as Einstein figured out.

Answer 4

I agree with Martin, in that Doug's answers your question best. If you look on the Hubble telescope website there are pictures of "Deep Space" and as you look closely more distant galaxies look bent or curved, this is due to the nearer galaxies providing enough gravity to bend the light and they, in essence, act like a giant lens bending the light passing through.

Light also bends in strong magnetic fields. I remember seeing this in secondary school (about 16 years old).

Answer 5

Your question isn't thoroughly clean. What do you mean with the help of emitting mild beams at an attitude? What i think of that it is likewise possible to work out is, that mild is scattered with the help of air molecules and with the help of smoke and dirt debris in the air, so which you rather see the air in and around the beam glow. in case you are trying your test in vacuum, you will see that mild is going immediately, without having the flexibility to work out the beam in any respect till you look suited into it. in accordance to Einstein's concept of regular relativity a immediately line is defined with the help of the course that mild takes in the curved area. as quickly as we be conscious that mild is bent with the help of gravity, we rather see what a curved area does with a immediately line in that area. it rather is like defining the equator to be a immediately line on the exterior of the globe: walk immediately forward on the exterior and you will finally end up the place you began.

Answer 6

Doug Donaghue's answer is the correct one. But, even so, some ******** has given him a "thumbs down"!

Answer 7

Because its lazy.

Look up Principle of Least Action (wikipedia is not bad).

Answer 8

because lts fast light travels faster then any other thing in this world or...... universe.

Answer 9

because it has no physical matter (weight and cornes and edges and such) to it for gravity to pull on or for air to resist against

Answer 10

It doesn't it bends, think of the colour spectrum diagram?