PeterR280
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Reged: 05/27/13

Re: Scary relativity
[Re: Otto Piechowski]
#6216084  11/25/13 08:50 PM

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Mass and energy equivalence is real too. If an object moved fast enough would it become a black hole?

PeterR280
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Reged: 05/27/13

Re: Scary relativity
[Re: PeterR280]
#6216135  11/25/13 09:17 PM

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Also with a disc going by the sun at relativistic speed, would it not appear that the disc is turning toward the direction of motion and block the sunlight across a perpendicular wave front? in other words, it would appear turned enough to catch the front part of the wave front.

PeterR280
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Reged: 05/27/13

Re: Scary relativity
[Re: PeterR280]
#6216138  11/25/13 09:20 PM

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if you were riding on the disc, you would see the earth as being foreshortened and you would see your disc blocking the earth.

deSitter
Still in Old School
Reged: 12/09/04

Re: Scary relativity
[Re: PeterR280]
#6216219  11/25/13 10:15 PM

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Here's a poem by Schiller (pardon the impossible translation)
Threefold is the mass of space; Restless goes it, without ceasing, Striving lengths, into the distance, Ever widening, all increasing, Bottomless, sunk to the depths.
An image now to you is given: Restless go you, always striving, Never standing still, If you would see the thing completed, Unfold yourself into the breadth, If you would fain create a world, Then you must climb into the depth, If you would be shown the essence.
Only persistence can lead ahead, Only depth can lead to clarity, And in the abyss, there dwells verity.
drl

GregLee1
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Reged: 07/21/13
Loc: Waimanalo, HI

Re: Scary relativity
[Re: deSitter]
#6216253  11/25/13 10:28 PM

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The increased mass of the moon would lens the Sun's light around it, effective magnifying the size of the Sun and preventing the eclipse. Maybe.

deSitter
Still in Old School
Reged: 12/09/04

Re: Scary relativity
[Re: GregLee1]
#6216257  11/25/13 10:31 PM

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Quote:
The increased mass of the moon would lens the Sun's light around it, effective magnifying the size of the Sun and preventing the eclipse. Maybe.
I would give you 3 points for creativity here. But it would be a 10 point problem.
drl

PeterR280
PoohBah
Reged: 05/27/13

Re: Scary relativity
[Re: deSitter]
#6216286  11/25/13 10:54 PM

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the important concept for the moon problem is the relative nature of simultaneity.

Rick Woods
Postmaster
Reged: 01/27/05
Loc: Inner Solar System

Re: Scary relativity
[Re: deSitter]
#6216313  11/25/13 11:21 PM

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Quote:
We just got started. There is a long hill to climb.
drl
We haven't even done that, and this thread is into its 5th page. I don't mean to sound impatient; but can we get ON with it?

scottk
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Reged: 08/29/09
Loc: Tennessee

Re: Scary relativity
[Re: deSitter]
#6216319  11/25/13 11:24 PM

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Has anyone said 42?
To the original poster: is it 42?
It's 42 isn't it.

Neutrino?
sage
Reged: 12/14/09
Loc: Wasatch Front

Re: Scary relativity
[Re: deSitter]
#6216389  11/26/13 12:30 AM

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Quote:
Also  VERY important  the Moon is not a disc, it is a sphere  were it a disc, the eclipse would NOT happen, and in fact, the faster that disc went, the more elliptical would become its outline. This is precisely the issue with graphical representation of relativity  the effects take place in space that is essentially 4D, and they cannot be reduced to plane descriptions  any more than any one flat map of the spherical world can be accurate in all ways.
drl
Sorry: Yes, I meant spherical. I was thinking spheres always present as a disc even at large velocities/subtended angle... that was why I was confusing circular in there.

PeterR280
PoohBah
Reged: 05/27/13

Re: Scary relativity
[Re: Neutrino?]
#6216430  11/26/13 01:35 AM

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Actually if the moon were a flat disc and you were sitting on it, you would see it casting a nice round shadow. You would see a flattened earth passing through the round shadow so the eclipse should last longer than expected.

Otto Piechowski
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Reged: 09/20/05
Loc: Lexington, KY

Re: Scary relativity
[Re: deSitter]
#6216656  11/26/13 08:40 AM

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For being nearly two centuries before GR and SR, that poem of Schiller's is eerily prophetic.
Otto

The Mighty Mo
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Reged: 10/12/13
Loc: South of North, North of South...

Re: Scary relativity
[Re: Rick Woods]
#6216937  11/26/13 11:02 AM

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Quote:
Quote:
We just got started. There is a long hill to climb.
drl
We haven't even done that, and this thread is into its 5th page.
I don't mean to sound impatient; but can we get ON with it?
I saw that coming yesterday, when Danny wouldn't answer our questions, and still isn't. That's why I bailed on actively participating in this...whatever it is... It could've been simply and easily answered in a couple posts several days ago in the original "Two Mirrors" thread.

dickbill
scholastic sledgehammer
Reged: 09/30/08

Re: Scary relativity
[Re: The Mighty Mo]
#6217074  11/26/13 12:11 PM

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Well I have some questions regarding the first post.
Let's say we have a 2 dimensional flat universe with a reversible Time, basically a plane where any transformation can be done in any time direction. Then we can apply the matrix transformation that drl gave us, for example the rotation. And so we got this matrix of sin and cosines and no Time member, because Time is not a part in the rotation transformation. And of course we got an important characteristic of this world: the distance between 2 points, a square root of x^2+y^2, and again no Time value because Time has nothing to do with the distance between points and the geometry of this plane. Now my questions are: 1) Are you using the Transformation to deduce the geometry of this world? or said otherwise, what is the rational to start with a Transformation here? why choosing a Rotation? why not a Translation or Magnification?
2)In a 3d world, the terms are basically the same with a distance in (x^2+y^2+z^2)^1/2, the addition of Time wouldn't change that. So why introducing Imaginary numbers, is it only to ease the calculation? And why is a term in Time suddenly appearing in the equation? I understand it is because of Light and its invariant characteristics, but this world also contains other objects whose speed is relative to other objects. So why is this world's geometry defined by the properties of Light and not, say, the properties of a canon ball?

deSitter
Still in Old School
Reged: 12/09/04

Re: Scary relativity
[Re: The Mighty Mo]
#6217093  11/26/13 12:21 PM

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Well since no one seems to want to follow the math, I'll just describe what happens. Hopefully I can do that OK.
If you made an even coordinate grid on the Moon, as on a globe, then the state of motion of the Moon would finally cause great distortion of this grid as speed increased. The surface features would seem to crawl around, be more densely packed here, less so there  but the apparent shape taken by the visible globe of the spherical Moon, would always be circular. What does such a statement really mean? And not just the Moon of course  any moving sphere, regardless of its state of motion, appears spherical, but it does not appear fixed  the distribution of its surface features changes. (The spectrum and intensity of the light are also affected, but that can be ignored for now.)
In the language of geometric optics, what we see is defined by a pencil of light rays drawn backward from our pupil to the physical objects that emitted (reflected, scattered...) the light. So the real question is not directly about lengths and clocks  it is about the nature of these pencils of light, and how they are affected by the state of motion. This is a very different question than making assumptions about the "actual state" of something.
That's the question to be answered. To do so, it is necessary to get some intuition for the way geometry itself is involved. This is the most amazing fact of all science  that physical geometry itself has changed for the first time since Euclid.
drl

choran
Carpal Tunnel
Reged: 12/28/12

Re: Scary relativity
[Re: deSitter]
#6217374  11/26/13 02:53 PM

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Danny, I don't think it's a matter of folks not wanting to follow the math, it is the inability of most of us to do so. It's been 40 years since my linear algebra and calculus days, and longer since trig. In the meantime, anybody who wants to see the math in the original 1905 paper on SR can go here.
Maybe the ones that can handle the math than then ask you questions.
Good luck!
http://www.fourmilab.ch/etexts/einstein/specrel/www/
][/url]
Edited by choran (11/26/13 02:55 PM)

brentwood
Carpal Tunnel
Reged: 11/04/05
Loc: BC Canada

Re: Scary relativity
[Re: deSitter]
#6217376  11/26/13 02:54 PM

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I do appreciate all the efforts here to try & get some of these concepts through to us thickies. The maths means nothing to me, I didnt even get the poem, but I did get Danny's post above about pencils of light. I can appreciate how we have to be patient in being explained properly. I have a similar frustration, but the other way around with trying to explain the remote for the TV/PVR/Soundsystem/Cable Box. I want to explain how the whole thing works, so it is understood so you don't have to remember it all but I just get asked not to "try and explain all that, just tell me what I have to press & in what order and I'll write it down".

choran
Carpal Tunnel
Reged: 12/28/12

Re: Scary relativity
[Re: brentwood]
#6217400  11/26/13 03:09 PM

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Brentwood, I believe that the heart of SR are the two postulates I posted earlier in the thread. It is the fact that the postulates force light velocity to be a constant for ALL observers that requires that time now become "dilated."
Try this rather lame, and probably wrong,example: You have pitcher throwing to a catcher. This pitcher always throws 100mph fastballs. Now, have the pitcher run at 10mph toward the catcher and throw. One would say "OK, the ball is now moving 110 mph. Or, have the catcher run toward the pitcher at 10mph. Again, most would say, "OK, the catcher will measure the ball incoming at 110 mph." SR says NO, by DEFINITION the catcher and pitcher will always measure the ball going 100mph. OK, so something's got to give, right? Since Velocity=distance/time, and since the velocity of the ball is FORCED to be 100mph, TIME is forced to become observer dependent and malleable. Now, please, everybody, don't jump on me. I'm not trying to be complete or even wholly accurate, just trying to give a sense of why SR REQUIRES time dilation as a consequence of REQUIRING that all observers measure light at a fixed C regardless of their velocity relative to the source, and regardless of the sources's velocity relative to observer. Again, once you accept the two postulates of SR, you are stuck with all the rest. The math getting to that point is tough for most of us.

Otto Piechowski
PoohBah
Reged: 09/20/05
Loc: Lexington, KY

Re: Scary relativity
[Re: choran]
#6217410  11/26/13 03:15 PM

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Well, that's what I thought was going on when folk here started to talk about the observation being a 4D phenomena for all involved and not a 3D+time.
Otto

PeterR280
PoohBah
Reged: 05/27/13

Re: Scary relativity
[Re: Otto Piechowski]
#6217455  11/26/13 03:38 PM

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A mathematician by the name of Minkowski, who used to be Einstein's math teacher, came up with a way to represent the mathematics of Special Relativity in geometrical form by formulating a 4 dimensional geometry of spacetime. The problems of SR could be solved geometrically. Einstein viewed this as a mathematical tool but later realized that the 4D spacetime geometry was the way to solve the riddle of General Relativity. The math that Danny was showing is the ultimate way to understand Relativity. If you understand what Danny is showing, you will be on the way to understanding General Relativity but it's not easy if you don't have a grasp of the fundamentals in trigonometry, linear algebra, etc.. You have to know what sine and cosine are, you have to understand complex numbers, you have to be able to manipulate matrices.
