But can't light be measured in terms of a proton and as a wave? And if light can be measured as a proton the doesn't it have to have mass, at least on a quatum level? I believe that the universe is 13 billion years old or however old scientists say it is, but for as much as I read about light the more and more it confuses me.
Light is unusual in that it behaves like a particle in some ways, but no, photons don't have mass. Or at least that's my understanding, I think at this level physics is so esoteric it's difficult to make absolute statements OR be constantly up to date. And the fact that it seems to act like a particle and a wave at times strikes me more as an indicator of our poor understanding of the universe than light doing its own damn thing.
Yeah there's particle / wave duality. These are the theories we use to describe what we see. You might be a bit confused though with a few terms - a proton is a particle with mass (and a few more properties) while a photon is a "massless" particle.
I agree. Einstein may have provided us with a lot of info and groundwork on this subject, but our grasp on this information isn't even close to being 100%. We're costantly learning things about time and space. I believe one day we'll be able to travel around like the starships in Star Trek. Someday, though.
When that happens you are compressing space, light is constant space and time are not. Actually, even when you say that light is "bent" with gravity it's actually space that is bent and light follows that path, kind of like a lens, a magnifying glass or a telescope do not speed up light, they bend it and spread the photos out (or focus them depending on how you use it). In a black hole the light goes straight in because it's escape velocity would be a speed that would be faster than C. Gravity can not speed up light.
Had to finally comment on a few things. That would depend on what type of vacuum you're referring to. In a perfect vacuum, there is no "ground" to speak of, as the gaseous pressure of the space would be absolute zero, indicating that nothing exists within it, including any ground. Even with partial vacuums, the effects of gravity are diminished. There has to be something there for gravity to affect, right? We do. There are zero g rooms (hell, there's a whole industry built around them). Airplane pilots can also recreate the effects by going into a freefall dive, where the occupants experience the effects of zero gravity temporarily. We also have vacuum chambers. Here is one that is used primarily to test the effects of space on shuttles. Combine the two, add a CAPS and bingo: a vacuum chamber with no gravity. Open space recreated on Earth (and cheaper than a shuttle, too). How do you think astronauts are trained before they go into space? It does because open space is considered a high-quality vacuum. The constant "c" is defined as the speed of light in a vacuum, outside of gravitational effects on said vacuum. Therefore, there is no contradiction between "c" and black holes. The speed of light is currently considered the fastest light (or anything) can go in ideal conditions. It does not say that light cannot be slowed down by the influence or interference of other variables, such as gravity wells or Earth's atmosphere.
You do know that even if there is no ground in the vacuum chamber, the chamber and everything in it are still in the earth's gravity? Cause if what you were saying was true, we'd be able to put a vacuum chamber on our kitchen table, suck the air out, and watch whatever item in it float around. Maybe I'm wrong, but I've yet to see a video of this EVER. My experience with vacuum chambers shows that it removes all the air, but gravity still very much has an effect on the contents. Whether or not there is any ground in the vacuum is not the deciding factor for gravity. If so, we could just jump straight up and once we lost contact with the ground, gravity wouldn't work and we could fly. I've never seen a zero g room. I am aware of the planes that simulate zero g that astronauts use for training. Thing is, it's not really zero g. It's just that the plane is falling at the same speed as the contents so they aren't pulled to the floor of the plane. They are still in the Earth's gravitational field as that is what's pulling them ( and the plane ) down. So a speed of light measurement test even in this situation would still be subject to the effects of gravity. The gravity isn't really gone on those plane nosedives. Thing is, even if you did combine the two processes above, it wouldn't change anything. The current documented speed of light was measured many years ago ( with inferior technology to today ) and NOT in a perfect gravity-free vacuum. It was recorded and everyone just accepts it as accurate. I'd like to see some new tests with better equipment done on the international space station. That way there is no gravity and we'd see if there was a change. Has it ever been retested in modern times?
Modern vacuum chambers allow operators to control any other fields within the chamber from outside, including magnetic (which can be used to negate the effects of gravity). Never seen a zero g room? Read on, then. My point is that zero g can be easily recreated on Earth, without the room floating up into outer space. Obviously, things inside the room would not be affected by Earth's gravity because that is what the room is designed to do. The outside walls of the room are still subject to the same gravitational pull as you and me (unless we're in the room, too). If by saying you've never seen one, you really mean you haven't heard of one where humans can safely exist for any length of time, you're right. Which is why most zero g experiments involving humans or animals are conducted in open space, usually in orbit around the Earth. And I'm quite positive that those experiments take into account the minute influence that Earth and all other astronomical bodies still have on them. From what I have read, it is a fairly common experiement and has been measured time and again in modern times. However, because the value remains constant, no one else has become famous for getting the same results. The last person to get famous by it was Michelson in 1926. But he was certainly not the last to conduct experiments to determine the speed of light. And if no one else has attempted to test against his results after 1926, why did it take another 57 years before the scientific community formally adopted the current value? Because tests and equipment were further refined for more accurate results, over and over again. Also, currently no one has been able to confirm the existence of a perfect vacuum (it's still considered a theoretical entity). Therefore, it would be impossible by today's standards for someone to conduct an experiment as you requested. Open space, as you call it, is actually a partial vacuum, albeit one of high quality. Gravity still affects the space station, though the effect is greatly reduced as the distance between the objects is increased. Based on this, any test to determine the speed of light in a similar vacuum would generate the same result, c.
The speed of light has been measured and remeasured. There are tons of people out there who want to prove Einstein wrong, so his theories have been continually tested. That's what gravity probe B was all about - go read up on the results of it's data collection, very interesting stuff in there.
I think I may have overstated earlier. (It's important, if you've made a statement and you got it wrong, to correct yourself!) For a distant observer, light does appear to move slower within a gravity well, and presumably, light in distant free space appears to move faster to an observer within a gravity well. This effect is caused by the time dilation due to gravity. However, and this is the important part, this is a mathematical artifact of the choice of your coordinate system. You can even choose a coordinate system where something appears to be moving at faster than 3e8 m/s. However, in that coordinate system, light will move still faster. All that means is your choice of coordinates is misleading. Locally, light always travels at 3e8 m/s, and time always ticks at one second per second. Even an observer within a black hole would see this. It's... kind of a mathematical illusion, I suppose, whereas the redshifting/blueshifting of light is measurable, as in the Pound-Rebka experiment. Incidentally, at Earth's surface time dilation due to gravity is very small, but still measurable. GPS satellites account for it, and in fact would shortly become useless if the correction factor was removed. It is certainly not enough, IG, to squash a 6,000 year old Earth into a 4.5-billion year old patch of universe, especially when independent evidence exists to date the Earth. I suspect the Earth's gravity would have to be strong enough in that case to smear us all into millimeter-thick meat patties in horrendous red sauce. Which, if we're created in God's image, would make the Sistine chapel REALLY weird-lookin'.
I took a general relativity class in college actually, I think my confusion was related to thinking about what reference frame the observer is in. I was under the impression that objects would only appear to be moving at speeds faster than the speed of light as a byproduct of the natural expansion of space, hubble constant? It's not that said objects are actually moving in excess of C, but the space between said object is actually increasing above and beyond what would be expected by their relative velocities. The expansion also occures between the photons, this lengthening the wavelength, shifting the spectrum, and giving the illusion that the point of origin is receeding from us at speeds above the speed of light. Is that right? It has ages since I looked at or thought about this stuff. Also someone mentioned photon's as being massless, wouldn't they have to have mass, at least in the sense that Energy is Mass, E=mc^2 and all that?
That's mainly what I meant, Kupp. I'm still not sure about the second half of the second sentence in my post, which is why I prefaced it with presumably.
I don't know much about how lights speed can be percieved as anything other than appropriate to the medium it is travelling in, but I recall these being a story about some scientists stopping light, but I don't remember anything about that other than the headline.
