Relativity graphics and videos

[Martin]

In case anyone might be interested:

 

http://www.anu.edu.au/Physics/Searle/

 

this site has free stuff to download and samples of the graphics.

 

If you have other good graphics of relativistic effects, or computer animations, please add them to this thread.

 

these are by a group in Australia. they look pretty good to me.

 

Here is a more commercial presentation of the same stuff, it looks like:

http://www.anu.edu.au/Physics/Savage/TEE/

 

Here is an article in an Australian physics journal about these graphics

http://www.arxiv.org/abs/physics/0508224

[wormholeman]

I viewed one of the animations from one of the links but I diden't quite understand it.

[5614]

The fact that length contraction doesn't occur perpendicular to the direction of the motion and that at those speeds the fact that light from nearer parts (of a small object) reach you first makes a noteable difference is all new to me (although I do know the basics of length contraction, time dilation, doppler shifting... not Terrel rotation though) so there's stuff to learn, thanks very much for the links Martin.

 

I know the thread was originally about websites, so with permission of Martin (the original poster) I would like to ask why Saturn's rings are not ring shaped, like here:

 

 

I can understand why they'd look different, but why does it make that shape?

[wormholeman]

Seems to me that the light rays from the star is pushing the rings were the light is focused.

[insane_alien]

its to do with the wide angle and high speed i think thats what the website says anyway

[wormholeman]

Or might it be the outward gravity from the star?

[5614]

hmm, I don't follow that nor most of the Saturn video, see here:

http://www.anu.edu.au/Physics/Savage/TEE/site/tee/movies/saturn.mov

 

Questions:

 

1) Why do the rings bulge in (previous post's question)

2) Why rings still distorted from backwards?

3) Why is the plannet magnified?

slight later on,

4) Why do the rings flip inside out as we pass between them and the plannet?

5) And why bend over us?

 

I need to learn about angular compression, otherwise except for the 5 above questions I understand the video (which isn't really much of it!) If anyone can help (preferrably keeping it simple!) it'd be much appreciated.

 

[edit] I know angular compression, am now trying to work out Terrell rotation

[wormholeman]

Ya. those previous posts I put about gravity and light are not correct.

 

Please tell me of your answers, im curious.

[5614]

Why the rings bulge:

 

It's to do with the fact that light leaves different parts of the rings at different times. So assuming we travel over the top of the rings the light from the side leaves the rings first, then we move forwards, then the light from the directly below you (a shorter path than the light to your sides) leaves. Because the light is leaving different parts of the rings at different time you see the rings in slightly different places.

 

It's easier to explain coming away from the rings, see here:

 

 

There are 2 frames seperated by a brown line.

 

Explanation:

 

1st frame:

 

black circle = plannet

black curved line = plannet rings

blue = observer

red circle = where we look back at plannet

green line = distance x meters

red/purple lines = light.

 

The light coming from the outter part of the ring's has to leave before the light coming from the center (nearest to us) part of the ring because it has further to travel.

 

In time between red line of light being made and then the purple (frame2) line of light being made the observer moves forward, you can see this because the green line in both frames is the same length, to we can see in frame2 the observer is green line + extra away from the plannet, whereas before he was only green line away.

 

Now he's travelled that "extra" distance the purple line is made.

 

In the next fram the observer enters the red circle, looks back and sees all the light at the same time.

 

The reason for the bending is because in frame1 where the red lines were made he was green line (x) away from the plannet, so when he enters the circle he sees the outter part of the ring as being x away from him. When he looks at the center of the ring he sees it as being x + "extra" away from him because the light was made when he was x+"extra" away from it... he sees the center as being further away from him, hence the effect.

 

=======

 

The reason it is magnified is due to the reverse angular compression. Angular compression occurs as you move towards something, we are going away from it so the reverse happens, see here:

http://www.anu.edu.au/Physics/Savage/TEE/site/tee/learning/aberration/aberration.html

 

It is very complicated to explain with words! I hope you might understand me a bit.

[5614]

4) Why do the rings flip inside out as we pass between them and the plannet?

5) And why bend over us?

Obviously the answer to this will involve a lot if not all of the effects of SR playing up at the same time and I cannot quite figure out, although I haven't worked on it for too long yet! If anyone has an answer then please let me know.

[wormholeman]

I understand your answers, and it sounds right. Thanks!

 

4) Why do the rings flip inside out as we pass between them and the plannet?

5) And why bend over us?

 

For both those questions, I really think its because of the angular compression.

 

[edit] (because traveling near speed of light when we pass between the rings and the planet)

[5614]

I don't, angular compression will just happen whilst you are accelerating, once you're at a steady speeds you won't really notice the effects of angular compression, like you will, but it wont be a moving effect, like whilst you are accelerating, it'd just be there.

 

The reason the rings flip inside out, well, this is badly worded, we are travelling through the rings, all that happens is first we are looking down at them and then as we travel through them we change camera angles to look up at the rings we just flew past.

 

It's like keeping your eyes on something which starts below you (so you can see the top of it) and then it goes above you (so you can see the bottom of it).

 

The reason they might be seen as flipping and the reason for the weird shapes and bends would be because of distortion (like in #1 & 2).

 

Or maybe angular compression gives the flipping sensation, either way its still to do with the fact that light leaves different parts of the rings at different times which is why they bend. If you watch the video carefully they don't really seem to flip much, if you consider that it is us moving through them and not them flipping.

[wormholeman]

Man! This stuff is hard to understand.. I think its way out of my league.

[5614]

Question 4 and 5 are becoming simpler every time I look at them.

 

The rings flip because you are going past them and angular compression seems to make it look a bit unusual, but hey, just watch the video and thats what it looks like!

 

And the rings bending, well, we've already covered that in post #9 and you said you understood that.

 

This stuff is hard, but hey, we're working on it!

[wormholeman]

Ya I did say I understood, but not all of it. After viewing the movie

I listened more to what the guy was saying, he mentioned Relativistic

aberation. (as per why the rings bulge)

 

This info is from your link you provided:

http://www.anu.edu.au/Physics/Savage/TEE/site/tee/learning/aberration/aberration.html

 

"Relativistic Aberration

 

The shape, position or orientation of an object seen by a person moving near the speed of light can be quite unusual, and even different to what is predicted by the non-optical aspects of Einstein's theory of special relativity, such as length contraction. This is due to the purely visual effects of angular compression and distortion."

 

The light theory I dont except. Because the observer is traveling at 99% light

speed and the star/sun is in front not behind.

 

Why the planet gets smaller when the observer approaces it while acellerates

forward and dose the opposite the other way, boggles me. But like you and the

guy said it was because of the effect of angular compression.

 

"Angular compression

As we travel faster, light appears to come at us from different angles. To understand why this occurs, imagine driving in a car on a rainy day. Although to a person standing on the road the rain falls straight down to the ground, from inside the car it looks as though the rain is falling towards us at an angle. In a similar way, as we travel close to the speed of light, the angles of light coming towards us from all sides appear to contract, such that more light approaches us from in front:"

[GeminiinimeG]

ok wouldnt you see the same thing no matter what. I mean if light travels in a straight line it means that you still going to see the same picture, perhaps your going to see a wider image because the straight lines are spread out wider or mayve your going to see regular image that is wider and has dark spots because light would be spred out like this....

 

 

 

Regular speed ||||||||

 

 

 

Speed close to that of light | | | | | | | |

 

Speed close to that of light spots between light rays would be dark becuse theres no light there for your eyes to capture. Interesting theory aint it, I am not familiar with this field so this is just a Theory

[ydoaPs]

not a theory!!!!!!!!!! geez! people, stop with the flippant use of the word theory.

 

that isn't how it works. images are distorted due to time dilation.

[wormholeman]

omit this

[wormholeman]

ok wouldnt you see the same thing no matter what. I mean if light travels in a straight line it means that you still going to see the same picture' date=' perhaps your going to see a wider image because the straight lines are spread out wider or mayve your going to see regular image that is wider and has dark spots because light would be spred out like this....

 

 

 

Regular speed ||||||||

 

 

 

Speed close to that of light | | | | | | | |

 

Speed close to that of light spots between light rays would be dark becuse theres no light there for your eyes to capture. Interesting theory aint it, I am not familiar with this field so this is just a [b']Theory[/b]

 

Actully ya..you have a point ..So the star/sun infront of the observer you see is actually behind the observer (Angular compression).

[wormholeman]

omit this too..sheesh

[5614]

No he doesn't have a point! Look GeminiinimeG I know you're knew here but I don't like you! Your speed of gravity thingy, now this, you don't know what you are talking about, yet you say things like you do.

 

Here we go:

 

ok wouldnt you see the same thing no matter what.

NO

 

I mean if light travels in a straight line it means that you still going to see the same picture,

No you will not, learn what you are talking about before talking about it.

 

perhaps your going to see a wider image because the straight lines are spread out wider or mayve your going to see regular image that is wider and has dark spots because light would be spred out like this....

Regular speed ||||||||

Speed close to that of light | | | | | | |

err' date=' NO.

 

Speed close to that of light spots between light rays would be dark becuse theres no light there for your eyes to capture

That is wrong too, c is constant.

 

Interesting theory aint it, I am not familiar with this field so this is just a Theory

It is not interesting and not a theory, you seem to know nothing about SR or any basic science.

 

So the star/sun infront of the observer you see is actually behind the observer (Angular compression).

Quite how you got that from what he said I dunno, things wont compress soo much that you see things which are directly behind you, but you will see stuff which is normally a long way out of your line of site (off to the sides). Things will compress, you have the right idea, but when you said "behind" if you mean literally directly behind you it's probably exagerating a tiny bit, but it's correct in principal.

[wormholeman]

I think im confused about all of this now, oh well it was fun...

[5614]

The compression thingy aint that bad! Watch the 10sec video here (the top one):

http://www.anu.edu.au/Physics/Savage/TEE/site/tee/learning/aberration/aberration.html

and you'll see that everything like moves around into the green dot's vision, except one arrow, that's what I'm talking about.

 

Understanding WHY this happens is hard, but just seeing what happens aint that hard at all.

[wormholeman]

Ya, I saw that too. I diden't know about that till I looked at it. I suppose

I do have a more understanding of the video.