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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.
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?
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.
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
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.