Photons from light bounces over all surfaces so why is there no remnant glow when you switch off the light?

Question

Since photon from stars can travel zillions of miles to earth into our eyes, the energy of photons should not dissipate that quickly that it does not last a few seconds after you switch off a light source.

Answer 1

You are in a 10-foot room with a light in the center. The photons leave the light, zoom to the wall in 5 nanoseconds, reflect off the wall, and (some of them) zoom into your eye 5 nanoseconds later, where your brain perceives them about 300 millisconds later.

You turn off the light. Generally, the light will cool and stop emitting photons within, say, 100 milliseconds. But suppose it is a specially-constructed light, and it turns off in 10 picoseconds. The last photons stream to the wall in 5 nanoseconds, reflect, and hit your eyes 5 nanoseconds later. Some of the photons that miss your eye may reflect off the walls several times, but there is a 20 to 80% chance of their being absorbed by the paint on the wall each time they reflect. The brightness in the room therefore decreases a factor of about 2 every 10 nanoseconds. Within 100 nanoseconds, the number of photons in the room has decreased a factor of about 1000, and it becomes dark.

Answer 2

Your statement of them not being able to dissipate quickly is clearly wrong. When photons of light strike a surface, some are reflected and some are absorbed; the only ones you see are reflected. In most cases, the energy that the photons confer to an object is not strong enough to excite the molecules so much that they glow. As soon as you switch off the light, all the remaining photons are bounced around and absorbed almost immediately (light travels very fast, you know).

The light energy you are talking about that sticks around after the light is off is actually converted into heat energy. You can't see heat (unless you have special equipment), but it's there.

Answer 3

Individual photons of light travel at the speed of light. Photons can interact with the electrons that orbit atoms and molecules kicking them into higher more energetic orbits. When the electrons return to normal (rest) orbits in one or more steps new photons are released and travel at the speed of light. Some objects when exposed to light will glow in the dark for a while as the electrons return to rest states. Black light (UV) can make certain objects glow the same way. But all photons released will either strike your eye or travel to an absorbing material or into space at the speed of light. Of course when you shut off a light bulb it takes the filament a very short time to cool to the point where light stops but infrared light will be emitted until the filament is cooler still.

Answer 4

photons from stars travel in vacuum

photons in your bedroom travel in air, and get reflected off surfaces. How do you think reflection happens, for example? The photon hits "something", say an electron, and transmits part of its energy to it, after which a photon is typically re-emitted, which differing characteristics but typically a lower energy. In air also, the photon interacts with atoms.

so pretty quickly because of all this, the photon's energy is dissipated.

Of course if you took more energetic photons, such as gamma rays, they would travel much further but since they wouldn't bounce, and you can't see them anyway, that wouldn't be much help ;-)

Answer 5

Because light moves fairly quickly. Therefore, when you shut the light off, you shut off the reflections.

With stars, the photons were "launched" millions of years ago, and are just on a journey. The difference is that in a room, the distances are fairly shorter than from a star.

Answer 6

In actuality there is a remnant glow; however, the speed of light is so fast that it last for only a nano second.

Answer 7

I'm guessing you would be able to see it if you could slow down time enough. Light is so fast that the naked eye can't see the repeated reflection and absorption of the light.

Answer 8

They get absorbed quickly either by atoms or molecules and turned into another form of energy

Answer 9

I assume waves dont glow.Pehaps photons are indestructible.

Answer 10

Because the surface doesn't absorb it. it just reflects it.