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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.
Lightspeed is a simulator for velocities at c and below. Screenshots are available.
Illegal? Samir, This is America.
I wonder what a website (and associated server/network tin) looks like when it's Slashdotted at the speed of light?
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Reduce the speed of light to 30 kilometres per hour! Then you too can ride at the speed of light!! Easier if you have a motor bike.
It's a Bagel.
I have seem something similar to this before. Check out:
http://www.anu.edu.au/Physics/Searle/
and
http://www.anu.edu.au/Physics/Savage/TEE/
Look, I've been through Tübingen at the speed of light, and it doesn't look anything like that!
eleven plus two / twelve plus one
All of science is a "theory." Do you think that's air you're breathing now? Or are you a brain in a jar? My theory says the former, but it could be completely and utterly wrong.
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.
And most of the alternatives are conjectures.
Scientists use words like chess masters use pawns; saying something's "just a theory" tends to have roughly the same effect on their mental state as kicking the board over.
For the love of God, please learn to spell "ridiculous"!!!
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?
That's wrong...Time would pass normally for you. You would think at a slower speed (the same speed you're moving) so you wouldn't notice a difference. When you got off the bike, however, much more time would have passed for everyone else than you.
All this is, of course, assuming Einstein was right (and I think some experiment somewhere proved these effects to be correct)
Those curved buildings are kinda cool, but how long would those buildings even be in your field of vision if you were blasting past them at the speed of light? I don't think your brain would get a chance to process that kind of detail before it blurred into the image from the next microsecond, which would probably be completely different. I'd say it'd all be a messy blur.
Looking backwards would be kinda sweet though, if it didn't blind you immediately.
or maybe that's brown bike shorts.
eww.
There is quite a bit of very convencing physical evidence for both special and general relativity. Here's the first google item returned, but there's lots more out there to read. http://math.ucr.edu/home/baez/physics/Relativity/S R/experiments.html
We must proceed with caution by ceasing these speed-of-light simulations. The Chinese would surely use them to advance their space-weaponization program.
Why does this troll keep showing up? The Chinese don't have the resources to compete with the US. They've attempted manned space travel several times (even outright copying the Dynasoar design) and every time have had to cut it because of the cost. For now, I wouldn't worry too much about the Chinese one-upping the US on their own technology. Start worrying when they launch an Orion (not bloody likely).
Note that the Chinese space program is completely under the auspices of the Chinese department of war. By contrast, in the USA, NASA is an entirely civilian effort.
This is a GOOD thing. Remember what happened when the space program was under the United States department of war? (Specifically the Air Force?) That's right, some good engineering was done, but we didn't GET anywhere. It wasn't until NASA was formed that the US actually got into the race.
Javascript + Nintendo DSi = DSiCade
This is what I see when I sprint to an all you can eat buffet after someone else has offered to pay. I have been called many things, but late for dinner is not one of them.
I prefer Ludicrous speed!
Even those who arrange and design shrubberies are under considerable economic stress at this period in history.
Wouldn't the blueshift when traveling at such speeds push everything out the visible spectrum? So you wouldn't actually see anything, you'd just get a nasty dose of Gamma waves... or worse?
common sense: noun
What those who are ignorant of the subject matter think; usually wrong.
It's in the this explanation. There's a diagram at the bottom which explains it much better than I can in words.
if, ignoring science and all that hoohah stuff, you could ride a bike at the speed of light around the place, would there be any need for traffic regulation or do collisions just become so hideously unlikely that it doesnt matter? /ot
Brain(s): 0.0% user, 1.3% system, 0.1% nice, 98.6% idle
I showed my wife the videos cause they were cool, but she got all misty-eyed about seeing Tubingen again, so I'm in for a long night of hearing about how much fun she had at university there. Sigh. Why can't more people appreciate the value of astrophysics for astrophysics' sake?
The world's only surviving livewriter.
Very cool project - the screenshots posted by the parent comment show nicely that the Tübingen Project forgot to adjust the colors - due to the Doppler effect, colors change dramatically.
Under capitalism man exploits man. Under communism it's the other way around.
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
There should, I think, have been at least a nod given to George Gamow whose 1947 book, "Mr. Tompkins in Wonderland," attempted to explain relativity and quantum mechanics by putting Mr. Tompkins into situations like this. If I remember correctly, one of the episodes literally did involve his riding a bicycle in a Wonderland in which c was something like twenty miles an hour.
"How to Do Nothing," kids activities, back in print!
"They put you in a driver's seat that both Armstrong the Astronaut and Armstrong the Cyclist would equally enjoy"
But what about Armstrong the overly stretchy action figure?
Everyone is entitled to their own opinion. It's just that yours is stupid.
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)
Well, at the speed of light... yes, things going at the speed of light experience nothing that can be called the progression of time.
But matter can't travel that fast, only things without mass. So, there is the interesting question of what you have that you would call a "bike" or "you".
Physics does not break at the speed of light, but intuitive physics is dead. Relativity is a strain on it at any high speed but just forget lightspeed.
(As I always do when this topic comes up, if you want a crack at understanding this stuff for real, try Reflections on Relativity, free online.)
Yes, a person moving faster than another is affected by time differently. Time Dilation is one of the components of Einstein's theory of special relativity.
"When I grow up, I want to be a weirdo"
t' = t / (sqrt(1-(v^2/c^2)))
Where v is your speed, c is the speed of light, t is the time that passes for someone at rest, and t' is the time that passes for you. If you plug a number in for the speed, say 30 kilometers meters per second (67k miles per hour) You would still be talking about a very small difference. Driving in your car at 80 Miles per hour would make the bottom of the fraction about equal to 1, meaning you wouldn't see any detectable difference.
No... Constant velocity = no acceleration. Constant high speed in a circle (such as in orbit)= lots of acceleration.
I'll never make that mistake again, reading the experts' opinions. - Feynman
That's Newtonian. The relativistic acceleration equations are different. See this FAQ for the correct equations, which will tell you how long (in either proper or inertial time) it would take to reach a given speed, as measured by an inertial observer initially at rest with respect to the body -- with some calculations for 1 g acceleration.
(For instance, to reach 0.77c requires 1 year of subjective time or 1.19 years of objective time; for 0.97c, it's 2 years subjective, 3.75 years objective; for 0.99999999996c it's 12 years subjective, 113,243 years objective.)
C'mon, surely someone else remembers the episode of Carl Sagan's series "Cosmos" where they did the relativistic motor scooter trick? In a small town in Italy, where the speed of light is only 40 km/hr (strictly enforced!) a young man leaves on a tour of the city at relativistic speeds, leaving his friend and younger brother behind. Sagan describes the effects of blue- and red-shifting, the contraction of the cyclist's length, and the dilation of time. It ends with the young man returning to the place he started, just a few minutes (in his frame of reference) after he left. Sadly, he finds all his friends gone, and only his once-younger brother, now an old man, still waiting for him.
I don't know why, but the bittersweet reunion of the two brothers, as well as the story of the late Wolf Vishniac in the "Blues for a Red Planet" episode, both make me cry.
I recall seeing still shots of a speed-of-light visualization in a brochure from Carnegie-Mellon's supercomputing center, back in the early '90s.
I can't find the brochure online (this was pre-WWW), but I think the stills came from this paper, from 1990.
Not that I think that this sort of thing is redundant. As technology advances, this is the type of visualization that's worth repeating on new hardware and new software.
k.
"In spite of everything, I still believe that people are really good at heart." - Anne Frank
Velocity is a vector quantity, basically speed times a direction vector. If you turn, it takes a force to push you in the new direction. Since F=MA, that means that you are being accelerated. If you were to drive a car in a clockwise circle at a speed of 100 MPH, it would be constantly accelerated to the right, but its speed would remain 100 MPH. However the net velocity would be zero, as the net spatial displacement would be zero (at least every time you come back to the start point.)
And orbiting bodies continually lost speed? What kind of troll weed are you putting in your pipe?
I'll never make that mistake again, reading the experts' opinions. - Feynman
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.
What you're talking about (the slowing down of light in glass, etc.) is the effect of light hitting a molecule of something, being absorbed by it, and then being reemitted out the other end.
Light's speed is a constant, c. It's the speed of absorbtion and reemission that changes it's apparent speed through substances.
I [may] disapprove of what you say, but I will defend to the death your right to say it.
The really interesting trips occur when you're travelling very near the speed of light, not at the speed of light.
In summary: Moving yardsticks shrink in the direction of motion. Moving clocks run slow. At the speed of light, Clock stops, Distance across the universe is 0 (All stars compress into a plane )
I looked at the front page, and I saw an article about OSS Java, that was posted a week ago!!!
/., I can read stories before they are even submitted!
Wow!! the effects of time/spped of light being made clear!
Now I don't need to subscribe the
#hostfile 0.0.0.0 primidi.com 0.0.0.0 www.primidi.com 0.0.0.0 radio.weblogs.com
If you're going to misspell a word, don't make it the one you emphasize in ALL CAPS...
Ydco co
Normally we use the words absorbtion and re-emission to refer to electron energy-level transitions within the molecule: photons are absorbed and promote electrons to higher energy levels; then, at a somewhat random time and in a somewhat random direction (not uniformly), electrons drop to lower energy levels and re-emit photons. (Note that these transitions aren't instantaneous, nor entirely well defined in time, but we call them quantum events anyway).
A notable effect of complete absorbtion and re-emission events is the tendancy to randomise the direction and phase of the radiation.
When slight slows down in a substance, this is different. It's due to coupling between the light and the molecules of the substance. Photons aren't absorbed in the sense of electron energy-level quantum transitions, but rather the passing photon wave packets interact with the electron waves to modify the phase of the photons. You could think of it as fractional absorbtion and re-emission, each molecule affecting the path and phase of each photon only a very small amount.
There is a qualitative difference between the two effects: light slowing down in a substance usually only randomises the phase and direction very slightly.
Here's a daft analogy. Light slowing down is like running through a vast plain of spinning merry-go-rounds, occasionally touching one with your hand or foot so that it affects your motion. Absorbtion and re-emission is like occasionally jumping onto a merry-go-round, waiting for a little with your eyes closed, then jumping off again.
-- Jamie
From the travellers perspective, they see that because the distance has shrunk, they're able to travel between the two very distant points in a lifetime. From an observers perspective, the traveller is able to do this because his 'clocks' all run super slow.
I'm making one assumption in writing this. I assume that your cyclist never turns his head. This seems like a likely assumption, since, if he does turn his head, there would be no need for relativity to explain why he can see the lamppost after he's past it.
What you're saying is, that a cyclist going at high speed past a lamppost will at some point see a mirror image of the back of the lamppost. This is flat out wrong. Which parts of the lamppost that are seen by the cyclist, does not depend on his speed.
The mental image I get when I read your post, is that of a cyclist, 'seeing' a billiard ball photon being fired from a lamppost - just as he is passing it - curving in across his path so that he runs into it. This is the ether explanation for the constant speed of light, disproved by the Michelson-Morley (sp?) experiment.
In fact, in any inertial system light always behaves the same. The relative speed of the lamppost emitting the photon, does not affect the behavior of the photon in, say, an inertial system where the cyclist is at rest at origo - apart from deciding what frequency it has. He can see it if it is incident upon him within his field of vision, not otherwise.
Objects going past you at relativistic speeds will indeed appear to be rotated. This is because the perspective you get of the closer part of the object becomes mixed with the perspective of the further off part, which is from an earlier time.
Imagine that a rod has two synchronized watches, one in each end. When the rod is some way off, you have a head-on perspective of it; as you go past it, you will see more of its side. Imagine that your eyes are so fast, that you can tell that the further off watch appears to be behind (whether the rod is moving or not), due to the fact, that the image of that watch has farther to travel. At relativistic speeds, you would then see the closer part of the rod curve away from you, since the side perspective, of the closer part of the rod, becomes mixed with the head-on perspective, of the further off part. (Drawing pictures would help at this point.)
However, the constituent perspectives in all this, are still the same that you would see, if you went past at a non-relativistic speed.
No, photons are massless particles. The modern usage of the term "mass" is that of "invariant mass" (of which "rest mass" is a special case, when applied to massive particles which can be at rest). A particle can travel at the speed of light if and only if its (invariant) mass is zero.
It is possible to define an "effective mass" for a photon of E/c^2, but that's not the sort of mass that is important in deciding whether something can travel at the speed of light (which is one of many reasons why the use of that kind of mass is deprecated).
Your basic assumptions are wrong.
First, it's not a perception only that objects contract in length in the direction of motion (remember, the frame of reference you are observing is always at rest! It's the universe that is moving, not you.) It's an actual contraction. Time dilation is likewise. The reason this must occur is because of the simple fact that the speed of light is the same in ALL frames of reference. This means the particle of light you see is travelling the exact same speed relative to you as the particle of light someone in one of the buildings sees as you zip past them.
There has to be some "give" in the universe to allow this to hold true. That "give" is the actual contraction of size and expansion of time.
The relativity effects are not simple perception distortions; the actual distance shrinks and time dilates. Objects get distorted in reality.
Finally, to you, those particles of light weren't "bending" to get to your eye. They travelled straight from the lamppost (or wherever the lamppost was when the light was bounced off of or emitted from it) to you. You can't see the back of the lamppost.
The radical sect of Islam would either see you dead or "reverted" to Islam.
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.