AFAICR, Chalnoth was already attempting to break the light speed barrier. It's possible that he won't see this thread for years (assuming he succeeded...and lived).
relativity and speed of light for dummies
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AFAICR, Chalnoth was already attempting to break the light speed barrier. It's possible that he won't see this thread for years (assuming he succeeded...and lived).
Yes thats the fundamental weirdness about the special theory of relativity.. You will observe the incoming light signal from say beacon A (taken in the frame of rest of beacon B) to be arriving at exactly the speed 'c', always... and measure the recession speed of beacon A to be always less than the speed of light. Regardless of how you set up your inertial frames.
Obviously something has to give way for this picture to be consistent. It could be either what we call 'distance' has to be changed or 'shortened', or it could be what we think of 'time'. It turns out both have to give. And exactly how they must change is given quite exactly by the lorentz transformation law.
Its so fundamentally counterintuitive to how we think off things, it arrives as a shock to every budding physicist when they first see it. But thats just the way the world works.
There is no technical explanation for this, it is what it is by experiment, and thats how its described.
You can write it down in progressively neater and more abstract packages (for instance by claiming the group SL(2,C)/Z2 is the group of isometries of spacetime relevant to the real world) but ultimately thats just putting fog over the issue.
Bigus Dickus
Regular
Fred answered, but you can rephrase that just a little more intuitively. Say you send out one beacon in one direction at .5C and another in the opposite direction at .5C - but this time, you go along with the second beacon (how else would you set out more beacons from that point as a reference?). Now, traveling along with the second beacon, which seems at rest to you, you send out more probes at .5C in different directions.
The resolution to your paradox, as Fred alluded to, is that whild the second beacon is at rest with respect to you, and everything seems normal, both your timeframe and distance measurements are altered when viewed from the perspective of the first beacon. From its point of view, you didn't seen out the additional beacons at .5C at all.
That's why it is called relatively - what looks like a given time, speed, or distance to you looks different from another point of view.
OpenGL guy
Veteran
Yes, I'm aware that it's all based on the frame of reference. The observer sees different behavior from the person travelling at relativistic speeds.
Also, regarding the poster's comment about "being everywhere in the universe simultaneously" it's actually quite the opposite: As an object approaches the speed of light it undergoes length contraction.
Yes, I know, I just wanted to clarify / add to your comment.
Dandruff? I'm sure after a few years in a space ship, by the time you actually get to a black hole, the shampoo will be long finished!
Very interesting. What happens to Quantum Mechanics though, as it is based on probability rather than strict 1+1=2 mathematics.. might be talking about something I have no idea about though.
Also the point of being at all points in the Universe at the same time for the traveller at light speed, my thought was that say I wanted to be in Alpha Centauri at light speed I would not experience the time it took to get there, same way as if I wanted to make a trip to Abell 2218.
For the traveller it takes the same time hence he can be at any point in the Universe in no time.
Relativity obviously says no, they don't but it's a meaningless concept anyway - we're not massless particles and we don't observe photons instantaneously travelling through every possible path from A to B (just the most likely ones, over a given length of time). The concepts of 'free will' and 'choice' in the world of the photon are equally as empty as 'time' and 'space' are.
I don't know how "free will" fits in physics. Clearly we don't have a physics "law" which has anything to do with free will. Only the randomness in quantum mechanics may provide some opportunity. However, since the randomness in quantum mechanics is supposed to be "true" randomness, it's doubtful that you can find real free will from it.
Of course, this is getting into philosophy instead of physics. An interesting idea is (from the parallel universe concept) that through quantum mechanics you can get infinite amount of all possible outcomes of the universe and your "free will" chooses the one you want (or, what you see now). This is of course just an interesting idea and has nothing to do with science becuase it's very difficult, if not impossible, to verify.
Of course, this is getting into philosophy instead of physics. An interesting idea is (from the parallel universe concept) that through quantum mechanics you can get infinite amount of all possible outcomes of the universe and your "free will" chooses the one you want (or, what you see now). This is of course just an interesting idea and has nothing to do with science becuase it's very difficult, if not impossible, to verify.
Oh yes we do, and those laws very strongly suggest that there is no such thing as free will in the sense that most people think of it.
Free will is an illusion, the result of (mis-)interpreting complex behaviour in complex system as the outcome of some mystical process. In many ways its similar to ascribing patterns in the natural world (weather, seasons, etc.) to the actions of Gods. A society with no grasp of any of the physical processes that happen in nature will see a bewildering array of behaviour, it will be very tempting to presume the existence of some magical cause.
The concept of free will persists because we observe complex behaviour being exhibited by a complex system (the human brain) about which we still understand very little of the inner workings. It's also tied up with the issue of consciousness, and where that little illusion comes from. People tend to say "I made this decision" rather than "this decision happened in my head". Trying to rationalise this to people in terms of physics is fighting a battle up two hills: against the deeply-ingrained notion of free will, and against the deeply-ingrained notion of a consciousness which is somehow independent of the physical instantiation of the brain which is supposed to host it.
Anyway, I guess this is a bit off-topic. Might be worth its own thread though, its an interesting subject, though arguing about it can rapidly get into science v. pseudo-science "but scientists thought the Earth was flat, so you must be wrong" regime pretty quickly.
I'll try. I don't understand it. Nobody really does.
Conservation of energy. You can't make it and you can't destroy it. There is a particular amount of energy and it stays that way.
Take a bit of the energy. It can express itself by being heavy(mass) or by moving (speed).
That is "e=mc2". Energy is Mass times speed.
Mass or speed. It's one or the other. So how fast does something go when you turn the mass all the way down to zero? When "something" weighs "nothing" it goes about 187,000 miles per second. Incidentally, that's about as fast as you should ever need to go.
That's as good as an explanation as I can give and it's totally worthless. We're evolved to operate in a particular environment. Some place with lots of water and a pleasant temperature and where things move pretty damn slow. Way too slow to have firsthand experience with nature at near light-speeds. We weren't supposed to experience zero gravity or anal sex either, but we slaughtered those cows so maybe someday.
Here's another cute-but-useless illustration:
Time works out mathmaticly as very similar to space. So if you have 3 spacial axis (X Y Z) you can more often than not throw time in there and the math works out. Now you can go along more than one axis at once. For example, going diagonal on a line graph. But if you can only go the speed of light and you want to go max speed in a particual direction, you have to pick one and only one. That includes time. So if you are moving full break thru space, you have no energy left to move thru time.
Now these illustrations are grossly innacurrate and agin -pretty much useless. But short of hunkering down and doing the heinous math required to actually see the implications of this stuff, they serve as nice tools to start getting the head around the idea.
Again, I don't understand it. The one implication that I can really get out of e=mc2 is that stuff is energy. Matter is frozed energy. That's heavy enough for me.
There's alot of popular science books that deal with physics and they all attempt to deal with relativity at some point. The best explanation I remember seeing was in Greene's Elegant universe. Should be available in paperback at any old bookstore.
Yeah, that's why I think discussions about "free will" belong to philosophy rather than physics.
I really don't like the whole time thing with special realtivity I find its rather pointless.
If you travel from A to B and back to A again it all cancels out. If you travel to point B and someone observes you from point A they can't actually tell if time has dialated.
If you travel via a worm whole from point A to B you've actually traveled back in time so you can observe yourself entering the worm whole but even without time dialation you could still see yourself entering the worm whole cause the light still takes time to travel.
And there is other stupidness poeople go on about. Like at the speed of light ( relative to earth) or very close a clock on earth would appear to be frozen. Thats BS the clock wouldn't appear because you A) photons would stop hitting your eyeball B) they would be so red shifted.
Also traveling at close to the speed of light does that actually increase the gravitational pull of the object? i.e. at very close to the speed of light a proton could have a gravitional fields as powerful as a black whole seeing it has such an increase massed. I really always though that the mass of the object doesn't increase but rather the inertia increased ( yes I know interia doesn't have an effect on the kentic energy formula however I suggest we could make a new formula ).
If you travel from A to B and back to A again it all cancels out. If you travel to point B and someone observes you from point A they can't actually tell if time has dialated.
If you travel via a worm whole from point A to B you've actually traveled back in time so you can observe yourself entering the worm whole but even without time dialation you could still see yourself entering the worm whole cause the light still takes time to travel.
And there is other stupidness poeople go on about. Like at the speed of light ( relative to earth) or very close a clock on earth would appear to be frozen. Thats BS the clock wouldn't appear because you A) photons would stop hitting your eyeball B) they would be so red shifted.
Also traveling at close to the speed of light does that actually increase the gravitational pull of the object? i.e. at very close to the speed of light a proton could have a gravitional fields as powerful as a black whole seeing it has such an increase massed. I really always though that the mass of the object doesn't increase but rather the inertia increased ( yes I know interia doesn't have an effect on the kentic energy formula however I suggest we could make a new formula ).
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Penrose, in his book "The Emperor's New Mind", argues that it is to do with physics, in particular quantum effects. I disagreed with some of his arguments but this aspect seemed quite plausible.
Bloody hell... Put like that, it's the first time i've EVER actually understood the time mess thing we were talking about...
Why do you keep saying you don't understand it... You made me understand it better!
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