can light penetrate the earths crust?
151737
some radioactive form of light can penetrate,e.g. X-rays
1088204
it depends on the fine partcles of water through which the light rays pass.if the condition is simulated it can remain for quite some time.
164037
The speed of light is much, much faster than the earth's rotation.
648382
In the vacuum light can get the high speed.\nAfter that you have gas, liquid an then solid.\nThis is because the density of matter. The more dense the matter is the more athoms there are, making it harder for the light to pass.
241158
The light from the sun goes about 186,000 miles in a second in a vacuum, which is a bit more than nine circuits of the earth.\n\n- - - -  - - - - - \n\nkirchwey caught me in another error:\n\nI did not previously bother to look up the circumference of the earth, but just winged it. Unfortunately, I misremembered/underestimated the earth's circumference by about 25%. \n\nThe circumference of the earth at the equator is about 24,901.55 miles. The speed of light in a vacuum is roughtly 186,282.397 miles per second, so the distance light travels in one second is equivalent to 7.480755 circuits around the earth at ground level at the equator, ignoring mountains and other orographic features.
522376
I believe it DEPENDS on the Frequency of that photon.\nWHITE lite comes into a prism (water droplets) and the\nindividual photos are BENT (refracted) various amounts\ndue to their frequency... thus we get to see the spectrum\n... rainbow... \nSo, yes, a photon going from one medium into another\nwould alter it's path a little at the juncture, \naccording to its frequency...  no "references", \njust my  off-the-cuff reply.  good luck.
123325
Yes, think stars.  VISION doesn't travel; LIGHT does.  So the question is how far can light travel, and there are no real limits to this--apart, perhaps, from the fact that light gets stretched by the expansion of the universe, and the red-shift "horizon" is at about 14 billion light years away.  But since there is nothing bright enough that the unaided eye can see, in practice it's less than that for things you can actually--rather than theoretically--see.
334395
Light is cool stuff.It acts like radiation but when it hits something it act like a particle.You cant see light until it hits something and it releases its energy.So most of the light after you turn the switch off hits something and ceases to be but a very small amount might be lucky to shine out to open sky and even less might leave earth.It will keep going till it hits something all happening at the speed of light.Like looking at very distant stars ,its taken billions of years for the light to reach us.The star is long gone switched off but we are still seeing the light from it very diffused but what we see hasn't hit anything on its journey and it's an infinitely small amount of what originally left that star/sun
567827
1-15 meters below the surface, this is also called the euphotic zone (or sunlit zone), which is where light penetrates.
14052
First of all, we need to remember that sunlight contains all the colors of the rainbow (after all, sunlight can be used to make rainbows!) Now, as sunlight travels through the atmosphere, it bumps into things. If it bumps into something big (like a bird, a plane, or Superman), it stops creating a shadow on the other side of the object. But if it bumps into something small, like water vapor or other molecules of gas, it gets sent into a slightly different direction than before (physicists would say that it "scattered") This scattering, however, is not the same for all colors; light at the blueish end gets scattered more than light at the redish end. So imagine a ray of light hitting the atmosphere at an angle. As it passes through, the various gases make the blue light spread out (some of it toward the earth and folks watching the sky) while the red light hardly gets scattered at all and zips by the planet. That's also why the sky on the moon is black even during the daytime. The moon has no atmosphere so nothing can bend some of the light (of any color) back to the surface.
985973
Actually this is quite possible.  The key is that the laser emits a wavelength which interacts with the N2, O2, and CO2 in the air.  Each of those molecules have specific absorption and emission spectra.  As they absorb the frequencies (research their respective absorption spectra through Wikipedia or Google) of the radiation (not necessarily light) that passes through them, the light will scatter with re-emission at different frequencies (their respective emission spectra), as if reflecting off of  an object.  They wavelengths are the important part, and not necessarily the coherency (as inherent in lasers) which tends to constructively interfere to produce "laser speckle."  The primary reason one might choose a laser is ability to key the energy on the specific frequencies of interest and to control the path of the light.  You would want mirrors on the ceiling and the floor to be perfectly aligned to allow the reflected beams to cover more area of the "laser wall" with multiple reflections from partial reflectors distributing the energy from a primary source through multiple small holes in the mirrors on the floor.  Alignment of the optics, and stability (environmental isolation) would be critical issues of the system.  Normal vibrations and movements of the geology and the house will interfere with the alignment unless properly isolated from it.
354495
A complex question that needs a highly simplified answer.\n\nA photon of light has different energy depending on the type of light, some light does go through us, but that ight is not visible to us.\n\nX-rays for example pass through things nicely, however they can be blocked sometimes by dense material (such as bone and metal), X-rays are a higher energy than visible light.\nEven higher energy is Gamma rays... a photon of this form of light can theoretically pass through several metres of lead, sometimes more.\n\nAt the other end of the spectrum is Infra red light, which is just outside our visibilty, when you feel it, it is heat. Consider that it can be easily insulated just by putting some sort of thick barrier between you and it.\nAlpha and beta radiation are such low energy that they are actually particles (fast travelling helium, and protons respectively). an alpha particle can be blocked by a thin piece of paper. A beta particle can be blocked by your skin.\n\nNow... visible light is between the extremes of theose above. As an experiment hold a torch to the palm of your hand and you can actually see light coming through. SO some light does get through. But most of it does not.\n\nVisible light is a happy medium with just enough energy for us to see. Any more energy or any less energy in the light and life would be difficult\n\nConside that if we could only see gamma rays then we would not see much at all, because the gamma rays would not bounce off anything.\nAt the other end, if we could only see beta particles then the world would be very dark because all the beta particles would be absorbed before they reached us.
933542
No.  But it's wavelength decreases.\n\n\nDoug
1104794
No.  Plants don't absorb much UV.  Grow lights are designed to emit light in the wavelengths that plants absorb, so get a grow light.\n\nWhat does the visible spectrum have to do with plants?\nPlants must have light to grow and survive in their environment. The plants specifically use light to make their food in a process called photosynthesis. The light is absorbed by the green pigment chlorophyll, which is located in the leaves of the plant. The actual colors in the visible spectrum that the plant absorbs and uses for photosynthesis are red and blue. The plant reflects green light, and that is what we see when we look at a green plant. Green light is not the only reflected light. For instance, far-red light is also reflected. Far-red is just outside the visible light spectrum. It is not visible to the human eye, but can be sensed by the plant. Far-red wavelengths are important to the plant because of the competition factor in nature. A plant can "SEE" when there are other plants close by because of the increase of far-red wavelengths the other plants reflect. This will then signal the plant to make the necessary adjustments within their system to try to outgrow the others around them since they are competing for sunlight and other resources.\n\nhttp://www.florence.ars.usda.gov/kidsonly/middle/mulch3.html
322915
No.  A laser beam, for example, can pass right through another laser beam as if it weren't there.  Light does not block other light.  You can easily see through a beam of light, unless there is a lot of particles in the air which scatter the light and dazzle you.  When you look at something you don't normally see the light in the room crossing your line of sight, only the light which goes directly into your eyes.\n\nThose laser beams you see in space in the movies?  That's just Hollywood.  In reality you couldn't see the beam from the side - light is completely transparent.
762871
False.  The light would reach us in about eight minutes -- and if the sun blew up, the light alone would be enough to kill anyone on the day side.
23843
Nope, everyone has it wrong.  There is a secret and even though we know it, we still cannot find the answer.  The questions is, "What is light."  Nobody knows what light is.  There are many theories, but none can be verified.  If we knew the answer to this question, there would be literally no limit to what could be known and done.  At one time we had no idea what electricity was, but, once we found out it's priciples and properties, look what was done with appliances and computers.  No, apply similar advances if we knew the principles of light.  A trip to Alpha Centauri (the closest star) would take shorter time to reach than Mars does now.