Relativity

Started by winkio, November 18, 2009, 08:26:08 pm

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winkio

So we finally finished mechanics in my class, and we are doing relativity for the last 3 weeks.  The universe has some seriously messed up shit.  Anybody else interested in this?

fugibo

Quote from: winkio on November 18, 2009, 08:26:08 pm
So we finally finished mechanics in my class, and we are doing relativity for the last 3 weeks.  The universe has some seriously messed up shit.  Anybody else interested in this?


Schrodinger's cat, dawg. Awesome sauce.

Of course, I'm going really slowly in my physics class. It's online, and I'm lazy as crap. I don't even properly understand springs and Hooke's law yet. Mainly because I've only spent around five minutes reading the Wikipedia article last night while I was half asleep.

winkio

QuoteSchrodinger's cat, dawg. Awesome sauce.


GET YO QUANTUM OUTTA HERE

I love how the fact that the speed of light is the same in all intertial reference frames just destroys all of classical physics XD.  And then from that, we get length contraction and time dilation.

fugibo

Quote from: winkio on November 18, 2009, 08:46:24 pm
QuoteSchrodinger's cat, dawg. Awesome sauce.


GET YO QUANTUM OUTTA HERE

I love how the fact that the speed of light is the same in all intertial reference frames just destroys all of classical physics XD.  And then from that, we get length contraction and time dilation.


Dawg, I just be playin' dice wid da universe! :V

legacyblade

^that's what D&D is for :P

I gotta say though, I LOVE relativity. Most of it makes a heck of a lot more sense than Newtonian physics to me (I have a really weird method of looking at the world physically, I think), and it's fun to think about :D

fugibo

Quote from: legacyblade on November 18, 2009, 09:29:24 pm
^that's what D&D is for :P

I gotta say though, I LOVE relativity. Most of it makes a heck of a lot more sense than Newtonian physics to me (I have a really weird method of looking at the world physically, I think), and it's fun to think about :D


I was making a nerd joke out of a reference to Einstein, who rejected Quantum physics because he believed that God did not "play dice with the universe."

The Schrodinger made a thought experiment about a zombie cat.

God, I love science.

Diokatsu

Schrodinger's Cat is a song in Pop'n Music D:

Can some one go through and give me the gist of what everyone is talking about *high school fysx*

fugibo

Quote from: Diokatsu on November 18, 2009, 10:51:11 pm
Schrodinger's Cat is a song in Pop'n Music D:

Can some one go through and give me the gist of what everyone is talking about *high school fysx*


Schrodinger's Cat

winkio

Einstein's theory of Relativity is built off of the fact that the speed of light is constant in all inertial frames.  That means that if you are standing still, the speed of light relative to you is 3 * 10^8 m/s.  And if you are moving at 2*10^8 m/s, the speed of light relative to you is still 3 * 10^8 m/s.  This has been proven true by experimentation, so then we have to come up with a theory to explain it.  It turns out that this with this new theory, not much changes until you move at 0.1c (c is the speed of light).  But as long as the speed of light is always constant, then all these other weird things happen.  Like when you observe something that is moving very fast relative to you, it gets shorter (length contraction).  And when you observe something that is moving very fast relative to you, its clock is slower (time dilation).  And then there's the doppler shift, which is where the frequency of perceived light is altered by the reference frame of the observer.  Basically,

legacyblade

@longfellow, -.- yes, I know about that. Then he responded "stop telling God what to do". I've read their works.

@winkio, aye, Relitivity is fascinating. It makes a heck of a lot more sense than quantum physics, I think. It only abandons absolutes, rather than abandoning many of the core concepts of cause and effect. Makes much more sense :P

winkio

QuoteIt only abandons absolutes, rather than abandoning many of the core concepts of cause and effect


explain.  I don't get what you mean...

legacyblade

The basic premise of quantum physics is that multiple states of reality can be true at the same time (everything is probability waves until we observe it. Think the Schrodinger's Cat experiment). This was one of the largest reasons Einstein refused to accept quantum physics.

winkio

Ah, you were comparing, I see.  For some reason, I thought you were saying something completely different. :^_^':

legacyblade

That happens a lot when I talk :P And yes, just comparing. I can understand the lack of absolutes (as found in relativity). But I can't get my head around the lack of true cause and effect and a single state of being. (the cat is alive or it is dead in my mind, it's not "a wave of possible outcomes waiting to be observed" it's a true/false value.)

Blizzard

You think relativity is messed up? Try string theory. #_#
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winkio

There is one large difference between relativity and string theory.  Mainly that relativity is accepted as true, while string theory is not.

Fantasist

Quote from: Blizzard on November 19, 2009, 03:57:18 am
You think relativity is messed up? Try string theory. #_#

Hahah, yeah!

Quote from: winkio on November 19, 2009, 08:08:10 am
There is one large difference between relativity and string theory.  Mainly that relativity is accepted as true, while string theory is not.

Not yet! >8U (I prefer my space stringy, not loopy.)

You know, I've been through 2 years of medium-level physics, chemistry and math. I'm done with being a science freak, but it's still nice. Brings back memories.
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Blizzard

Quote from: winkio on November 19, 2009, 08:08:10 am
There is one large difference between relativity and string theory.  Mainly that relativity is accepted as true, while string theory is not.


Of course. I just wanted to point out that string theory is even more messed up. But yeah, quantum theory is already quite messed up. "You're not supposed to understand it, you're just supposed to know that this is how it works.", that's what my professor said. xD
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Quote from: winkioI do not speak to bricks, either as individuals or in wall form.

Quote from: Barney StinsonWhen I get sad, I stop being sad and be awesome instead. True story.

Diokatsu

Relativity sounds interesting and I think I got the explanation you gave winkio. Not that I expect to understand it's applications and what that entails, but I think I got however much you explained of it. But quantum physics seems kinda fishy if I'm understand what LB said....

legacyblade

Quantum phsyics is founded on how subatomic particles (electrons and the like) behave. Our current methods of observing them make it seem as if unless we're observing them, they behave like a wave of probobility. (if we observe them, they act differently) I wonder if it's just our limited means of observing them. It's really confusing to me

Aqua

Ah we talked briefly about that in Chemistry last year.

The way that we'd observe an electron's path is by using an election to locate the election we want by having them collide to see where they are... Of course... this would only change the path of the elections, therefore messing up the observation.

Diokatsu

Quote from: Aqua on November 19, 2009, 07:20:19 pm
Ah we talked briefly about that in Chemistry last year.

The way that we'd observe an electron's path is by using an election to locate the election we want by having them collide to see where they are... Of course... this would only change the path of the elections, therefore messing up the observation.

Irony. The only way to observe the electron's path is to change it. Paradoxical as well.

winkio

So I just read this Feynman lecture about curved space.  Crazy cool stuff.  A straight line in 3d space is actually a parabola.  Gravity distorts time and all.  Anybody else know enough about this to discuss?

Blizzard

I do. I just love the concept of displaying an X dimensional space with and X - Y dimensional space where X > Y and Y > 0 and then folding that X dimensional space via the X+1'th dimension to bring two points in the X dimensional space at the same location in the X+1'th dimensiona space. It makes perfect sense and it applicable to any number of dimensions.
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Quote from: winkioI do not speak to bricks, either as individuals or in wall form.

Quote from: Barney StinsonWhen I get sad, I stop being sad and be awesome instead. True story.

winkio

no, not that kind of curve.  The kind of curve where a sphere is a curved 2D surface which has different geometric properties that that of a plane.  For example, on a sphere, you can make a triangle with 3 90 degree angles.  That kind of curved space.

Blizzard

But isn't that done over the overlying dimension?
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Quote from: winkioI do not speak to bricks, either as individuals or in wall form.

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winkio

November 27, 2009, 11:41:13 pm #26 Last Edit: November 28, 2009, 12:00:05 am by winkio
Yes, but what is the 4th dimension of space?  It's impossible to imagine.

Also there is no folding, just curves.

Blizzard

The 4th dimension isn't space, it's time.

Alight, no folding. xD
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Quote from: winkioI do not speak to bricks, either as individuals or in wall form.

Quote from: Barney StinsonWhen I get sad, I stop being sad and be awesome instead. True story.

fugibo


winkio

No, there is a fourth dimension of space.  I'm serious.  meters^4.  That's what I'm talking about.  And that is what space is curved in.  The curve does affect time though.

Blizzard

But dimensions are independent on representation. It's just a matter of perspective. We perceive the 4th dimension as time and that's that. We can just say it's another space dimension and just work with that, it doesn't matter.

EDIT: Hypercube. <3
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Quote from: winkioI do not speak to bricks, either as individuals or in wall form.

Quote from: Barney StinsonWhen I get sad, I stop being sad and be awesome instead. True story.

winkio

No, this is not a perspective, this is Einstein's Theory of Gravitation, which obviously, none of us have heard about until I just read this lecture on wednsday.  There's no way I'm going to be able to explain it, because you need some background in relativity, and because I don't fully understand it.

legacyblade

You're misunderstanding Blizz. The fourth dimension IS time. Time was previously thought of something independent of space. (events occurred in space at a specific time) However, Einstein said that rather than our current understanding of space as three dimensional (x,y,z,), it was in fact four dimensional (x,y,z,t) using time as the fourth dimension. Now if I understood what I read in his works correctly, the first three dimensions (x,y,z) are curving into the fourth dimension (t, or time). I've read Einstein's actual work, and me and my tutor talked about it for hours, so yes, Blizz and I are both correct in saying time is the fourth dimension. Einstein said so multiple times, and if you read his mathematical equations, it uses time as the fourth dimension.

winkio

I'm not talking about THE fourth dimension.  That is the list of observable dimensions.  I'm talking about space's 4th dimension, which is not time.  None of Einstein's relativity equations use time as the 4th dimension of space.  You can not multiply two areas and get seconds.

Time is related to space, not directly by being the fourth dimension of space, but by being its own dimension dependent on space.  Einsteins Relativity equations define this relation.  The curve of 3D space influences time causing time to curve, but space does not curve into time, it curves with it.

Space-time, combining the two related factors, is expressed in terms of x, y, z, and t, but space-time still curves into the next dimension.

Blizzard

Seconds and meters are just measurement units we use. You can say meters * meters * meters * meters or meters * meters * meters * seconds.

Of course space curves into time. If you take freeze the time flow and use 3 vertexes to make a triangle where you put one vertex in one frame of time while the other vertexes are in another frame of time, you have a hyper triangle curved through a fourth dimension (time). You can do absolutely the same thing if you say the 4th dimension is space and displace the vertex using it, you get curved the edges and a hyper triangle as well. I'm generalizing the concept of dimension here. It doesn't matter how you call dimension a 4th dimension.
I'm not saying that space and time are the same, I'm saying that using space and time as dimensions is the same.
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winkio

Yes Blizz, you can define space-time as a four dimensional entity, but that does nothing to explain the curving that we observe.  Whether you isolate space or look at space-time, both things still curve into a higher dimension, which is neither space nor time.

Blizzard

Alright, now we're on the same wavelength. :)
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legacyblade

OH, so that's what you mean. I've heard of that, but it was always rather confusing to me. Have we yet discovered what this extra dimension is? I know that large objects bend space time (thus creating gravity), but I've heard only a small amount of this extra dimension (so little that I'd forgotten about it till I heard Winkio's explanation as to what he was talking about). Anyone have more information about it? (at this second I feel too lazy to google "relativity" or "fourth dimension" until I find one that speaks on this subject)

winkio

Yes, so the lecture I read was from the Feynman lectures on Physics, Vol II Chapter 42.  I couldn't find it on google on a preliminary search, so I'm going to scan it and upload it soon.  It's quite an interesting read.

Blizzard

I might take a look at it. Me and my roommate were discussing higher dimensions recently. Stuff like the 5th dimension being alternate timelines, the 6th being alternate parallel universes etc.
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legacyblade

That sounds like some interesting stuff. I can't wait to take a look at it o.o (I LOVE theoretical physics. Not so hot on the applied science though, it's less interesting)

winkio


Ryex

I'm nobody appreciates your hard work in scanning that lecture, personally I would read it, but it's not there any more. however I think I would be better of starting with something the introduced my to the subject a bit better than this tread dose. while I always been interested in the subject I've never really looked into it. perhaps it could tell my what negative mass would really entail :P
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winkio

I'll reupload it sometime later this week.

Caligatio

Quote from: Arceus on November 18, 2009, 11:35:00 pm
Einstein's theory of Relativity is built off of the fact that the speed of light is constant in all inertial frames.  That means that if you are standing still, the speed of light relative to you is 3 * 10^8 m/s.  And if you are moving at 2*10^8 m/s, the speed of light relative to you is still 3 * 10^8 m/s.  This has been proven true by experimentation, so then we have to come up with a theory to explain it.  It turns out that this with this new theory, not much changes until you move at 0.1c (c is the speed of light).  But as long as the speed of light is always constant, then all these other weird things happen.  Like when you observe something that is moving very fast relative to you, it gets shorter (length contraction).  And when you observe something that is moving very fast relative to you, its clock is slower (time dilation).  And then there's the doppler shift, which is where the frequency of perceived light is altered by the reference frame of the observer.  Basically,


Believe it or not, I surely understand now. Thanks, I didn't got the whole thing of the speed of light shit, but now it's all clear!