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Excursions at the Speed of Light
D4C5CE writes "S/F fans can finally find out what you really get to see at relativistic velocity, and tourists are one step closer to "doing Europe in a day" in these amazing Space Time Travel simulations of the Theoretical Astrophysics & Computational Physics department at the Institute for Astronomy and Astrophysics Tübingen. They put you in a driver's seat that both Armstrong the Astronaut and Armstrong the Cyclist would equally enjoy, in simulators built to ride a bike at the speed of light."
I'm presently ingrossed in Brian Greene's new book called "The Fabric of the Cosmos" and does a wonderful job at creating lively understandable analogies while sticking to alot of interesting science. He covers the history and philospophy of how problems involving realtivity, time, and space have evolved - stronly reccomend it...
If religous zealots don't believe in Evolution, then why are they so worried about bird flu?
What about the G forces at the speed of light? Does it just rip peoples skin off?
I like muppets.
it has always been difficult to me to understand modern physics since they generally aren't so full of 'seeable' stuff like classical physics. this is a dream come true for a computer guy who wants to know more about the rules of the world around him.
The idea, while cool, is not that new (although doing it interactively might be). There's always the Relativistic Raytracer (more movies), which has been available since 1997.
All this does is attempt to simulate the visual distortion that one would perceive when traveling that fast. The videos look like you could be going 100 mph or whatever in terms of speed, but the distortion of the buildings seems to be what they're trying to get across here. The idea that you could have a long enough street lined with similar enough buildings to even perceive this distortion is beyond fantastical, so there doesn't seem to be a whole lot of point to this other than illustrating the notion that there is visual distortion. But I imagine what you would actually see would be much more of a blur.
I always understood that distances lying on lines parallel to your path (e.g. the length of a passing storefront) got shorter as you approached c. In the video it looks like the storefronts remain a constant length, or maybe even expand, as the speed increases. Am I missing something?
G Force is a quality of excelloration not speed. If you could excellorate at half a G you'd eventually achieve the speed of light and feel very little excelloration. There are real problems like the mass and the fact even tiny objects can strike with the force of an atomic blast. Achieving light speed is a kind of sucker bet. As you near the speed of light the energy required to continue to excellorate increases. No source of energy known can overcome it's own mass to reach the speed of light. There was a proposal to build an enitre ship out of bags of hydrogen ice so the mass would be reduced as you excellorated and there'd be little wasted mass. Even then I think it was unlikely to hit better than half the speed of light. Antimatter is a good option but still couldn't overcome the mass energy issue. In normal space it's unlikely that speed of light will ever be achieved let alone passed.
Sure.
See light travels at the speed of light. You cant travel faster, or even AT the speed of light.
But if youre zipping by an object that emits light, and its light doesnt travel in the same direction as you, its speed component in that direction is also slower than the speed of light, and you can catch up and see the object after you're past it.
Lets try that again.
Imagine youre on a bike, zipping past a lamppost. The light the lamppost emits travels in all directions. Now take the photos that are emitted in the same direction youre going, at the same time that youre just crossing the lamppost... now youre travelling parallel to that photon, although it beats you in speed.
However, if the lamppost was say 10m away from you when you zipped past, the photon you'd see is the photon the lamp emits not in the same direction youre travelling, but slightly towards you. If youre travelling north, the photon is travelling northwest, towards you. After youve crossed the lamppost, some distance later, the photon reaches you, because it had to travel a bigger distance, going in your travel direction (north) as well as towards you (west), and we all know the hypotenuse is longer than the base or height.If you travelled faster than the photon's north speed component, you'll see greater than 180 degrees around you... but never 360.
"Give orange me give eat orange me eat orange give me eat orange give me you." -Nim Chimpsky
They are missing the blueshift you would encounter at that speed. However I guess they couldn't be accurate because wouldn't the frequency would shift to far above the ultraviolet quite quickly?
History will be kind to me, for I intend to write it - Sir Winston Churchill
At forward viewing angles, yes, the images would be blue-shifted, but this doesn't mean everything goes dark. Visible becomes UV, and infrared becomes visible. But this is angle-dependent. Light arriving from behind you is actually red-shifted.
And yes, pushing several hundred watts per square meter of visible light into the UV range would result in a terrible sunburn.
But the point is that while you are going the speed of light, while time appears normal to you, you will have traveled an infinite distance in that first instant of time in your reference frame.
Which leads to the observation that you could never stop going the speed of light, because when you decide to hit the brakes X seconds later, you would have traveled an infinite distance. Where would you end up? (Never mind the problem of having to dissipate infinite energy)
You make some interesting points, but I should point out a couple of things.
If you are a human, eventually the things in front of you will be blueshifted out of the visible spectrum, and the back will be redshifted, so everything will go 'dark' (light non visible).
The direction of the shift will depend which way you are facing. Also, bear in mind that although the human-visible spectrum will be shifted out of the human-visible range, depending on your direction, one side of the human-invisible spectrum will be shifted in. So it may not go dark at all, it could even get brighter, depending on how bright the human-invisible component is.
There will never be a 'boom'
Regarding the boom, bear in mind that we really haven't gotten anywhere near lightspeed, so we don't know. At one time it was theorised that it was quite impossible to break the sound barrier. It is not only possible but quite likely that our understanding of what happens near lightspeed is inaccurate. What I've said is just my hunch, no doubt what you said, yours as well.
OK, I am going to pick nits. At the speed of light, there isn't much point to turning to see the sights. Due to length contraction, everything except directly in front of or behind you is now visible at a 90 degree angle to your path.
And, due to time dilation, you don't have the ability to decide to turn in your reference frame. Your entire trip at the speed of light must be zero duration in your reference frame to be of finite duration to outside observers.
Of course, if they simulated those two effects, the bike ride wouldn't be very interesting.
You're right. The rate at which you receive photons goes up as gamma, and the power received goes up as gamma^2 (since the photon energy goes up as gamma too). This is apparent dimensionally: rate of photon reception has units of 1/time, and time gets contracted by time -> time/gamma, so photon reception rate transforms like 1/(time/gamma) = gamma * 1/time, so is multiplied by gamma. Power has units of energy/time, which transforms (gamma energy)/(time/gamma) = gamma^2 energy/time.
Close. Everywhere collapses into a point around them, such that the distance travelled is none. So, every time you turn on a light, you are causing distortions in the fabric of space/time. And you thought you're dad was just trying to save a couple cents on the electric bill by harping on you to turn the lights off when you weren't using them.
For people really wanting to see how it would look to travel at the speed of light, you could always try the open source 3d space simulator Celestia.
I find that watching planets whiz by as you travel at the speed of light is pretty entertaining. I've had some fun just trying to steer with a joystick at this speed.
Of course, I suppose if you really were going this speed (or even 99.9% of it), you'd see some wierd spectral shifting (or that circular blur effect as in the article's animation), which is not shown by celestia.
Slow Light is around 1.6 Kms per hour
Quidquid latine dictum sit, altum videtur
I have issues with Einstein's theories. While I agree they match what we see, I don't agree that's what's actually happening.
It'd be like me saying that radios work because they have little people in them singing and playing instruments. They watch the knob from the inside and have a clock to tell what to play. That would explain the behavior, but it raises other problems. Now you might say "well we can open a radio and see what's in it". Gee thanks Cpt Obvious. Now make that radio the size of a quark and maybe you'll get what I mean. We can't look in it (at least yet), so all we have are theories. Give me a million more years of science and your theory will look sillier than my take on radios.
Einstein believed until the day he died that the entire universe must be predictable down to its smallest scale, however deep that may lie. He couldn't accept that quantum physics was inherently random, and thought that it was just a matter of making precise enough observations of quantum systems to be able to predict them with certainty.
So, you have a photon. It has no mass, so it always travels at c in a vacuum. Since it travels at c, in its frame of reference the universe has no duration and no length. It is emitted from one atom and absorbed by another instantaneously, from its perspective. Also, the rest of the universe exists outside the photon's light cone (which incidentally, has a zero radius and zero length), so the rest of the universe is therefore completely irrelevant to the photon. Remember also that every frame of reference is perfectly valid.
This means that for every photon that ever has been or will be emitted by one atom and absorbed by another, there is a relativistic frame of reference in which those two atoms are tangent. That means, for example, that if you turn your naked eye on the light from a star 100 light-years away, photons emitted from that distant sun 100 years ago are striking your retina, and for those photons the entire universe is a single point that bridges the star and your eye instantaneously. It must have therefore been "known" 100 years ago when the photon came into being that it would strike your eye, and therefore by extension the entire universe must be completely deterministic.
My head hurts thinking about it.
In doing some reading on Einstein's General Theory, I ran across the idea that Einstein's theory of how time dilates in the presence of an intense gravitational field could be proven by a red-shift in light affected by that gravitational field, the light functioning as a "clock" that would shift its spectrum in direct relationship with the gravitational time distortion.
Fine, I thought. Light does make a pretty reliable and observable clock. So, what does that mean for the Special Theory? Well, for objects moving away from each other, no problem. At relativistic velocities, there would be a red shift, which would fit with Einstein's theory of time dilation. However, since the Special Theory suggests dilation as the only relativistic time distortion caused by high velocity, any blue shift experienced by converging objects is really problematic. Blue-shifted light would indicate a contraction of time, something that the Special Theory doesn't consider at all. But maybe we should.
Do a few thought problems, and it becomes clear that, at least with regard to velocity, time dilation is but one side of a two-sided Doppler coin.
The Special Theory is great, but maybe not the last word, even in dealing with just velocity effects. It doesn't pay much attention to vectors. It hints at but doesn't really address the possibility that, when two objects have a relationship of extreme velocity, what is most distorted by relativistic effects is not either object's length, mass, or passage through time, but each object's ability to use light to "observe" the other, particularly with regard to its location and velocity.
After one hundred years of digesting the Special Theory, we really ought to be doing more than creating more dazzling illustrations of it. It needs correcting and refining, too.