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Neutrino?
sage

Reged: 12/14/09

Loc: Wasatch Front
Re: Scary relativity [Re: PeterR280]
#6215880 - 11/25/13 07:00 PM

Quote:

First of all Special Relativity deals with inertial reference frames without acceleration or gravity. Why introduce something like an orbit if you are explaining Special Relativity? It makes it even more confusing.

We aren't dealing with gravity, acceleration or orbits.

The set up is simple: As seen from the Earth, the Moon perfectly blocks the Sun (assuming both are circular) during an eclipse. Now, imagine the Moon now has some respectable fraction of c velocity with respect to our Earth frame. You mentioned Lorentz transformations are easy before. Applying these transformations, from our Earth, we expect there to be some contraction of the diameter of the Moon in the direction of its motion. Thus, the Moon is no longer circular.

The question is...do you still "see" an eclipse?

Edited by Neutrino? (11/25/13 07:04 PM)

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Crow Haven
Pooh-Bah

Reged: 01/09/09

Loc: Oregon USA
Re: Scary relativity [Re: PeterR280]
#6215884 - 11/25/13 07:03 PM

just confused...
Quote:

the Moon is no longer circular.

The question is...do you still "see" an eclipse?

...if it only changes size in one direction wouldn't it still be possible to be large enough to briefly eclipse the Sun????

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brentwood
Carpal Tunnel

Reged: 11/04/05

Re: Scary relativity [Re: Crow Haven]
#6215891 - 11/25/13 07:11 PM

Unbelievable! Someone asks what the Lorentz contractions are and someone answers "L = L0 * sqrt(1 - (v^2/c^2))"
I had to think what 'tangential' meant. Oh it is so difficult flapping around like a chicken when we are trying to soar like eagles! (Of course one could say that the Eagles should come down into the barnyard every now & then!)

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Otto Piechowski
Pooh-Bah

Reged: 09/20/05

Loc: Lexington, KY
Re: Scary relativity [Re: deSitter]
#6215896 - 11/25/13 07:13 PM

I'm waiting for Danny to explain to me/us why the moon would not, not eclipse the sun in this scenario.

Danny…just ignore all the 2nd through tenth row students. I'm in the front row. I left the red apple on your desk. I'm all ears…err…eyes.

Otto

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Neutrino?
sage

Reged: 12/14/09

Loc: Wasatch Front
Re: Scary relativity [Re: choran]
#6215900 - 11/25/13 07:13 PM

Quote:

Yup. Rabbit Hole dead ahead!! I think when Danny gets back we're all in for it. Teacher leaves the classroom and everybody acts up. LOL

I wouldn't call it a rabbit hole. It really is just a matter of when speaking of observation that we must carefully define what we mean by "see", or using "moving clocks run slow".

These guys are used in analogies without care to define what they really mean; both have stipulations that can't be ignored. Not defining them properly propagates into people saying "time slows down" and such.

Edited by Neutrino? (11/25/13 07:16 PM)

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PeterR280
Pooh-Bah

Reged: 05/27/13

Re: Scary relativity [Re: Crow Haven]
#6215908 - 11/25/13 07:16 PM

here is a similar problem you have a rod that is 10 feet long and it is traveling over a hole the is 9.9 feet long. it has a strong downpull. The rod will contract if it is moving very fast. Will it fall through the hole?

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EJN
Carpal Tunnel

Reged: 11/01/05

Loc: 53 miles west of Venus
Re: Scary relativity [Re: Otto Piechowski]
#6215918 - 11/25/13 07:20 PM

deleted

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Otto Piechowski
Pooh-Bah

Reged: 09/20/05

Loc: Lexington, KY
Re: Scary relativity [Re: EJN]
#6215942 - 11/25/13 07:28 PM

Thank you for that EJN, but I don't have the correct plug-ins and do not wish to install any on this machine. Can you explain it to me in words? Otto

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EJN
Carpal Tunnel

Reged: 11/01/05

Loc: 53 miles west of Venus
Re: Scary relativity [Re: brentwood]
#6215949 - 11/25/13 07:30 PM

Quote:

Of course one could say that the Eagles should come down into the barnyard every now & then!

Well, the Eagles came down to Allstate Arena last month and put on a really fine concert.
Welcome to the Hotel California.

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brentwood
Carpal Tunnel

Reged: 11/04/05

Re: Scary relativity [Re: EJN]
#6215955 - 11/25/13 07:33 PM

Ok, got that, the contraction is real but we do not see it so there is still an eclipse. Thanks, Diagrams good, maths & equations not!

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brentwood
Carpal Tunnel

Reged: 11/04/05

Re: Scary relativity [Re: EJN]
#6215961 - 11/25/13 07:36 PM

With this thread, I feel like I'm in Hotel California! I just hope they'll let me leave!

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Otto Piechowski
Pooh-Bah

Reged: 09/20/05

Loc: Lexington, KY
Re: Scary relativity [Re: brentwood]
#6215988 - 11/25/13 07:52 PM

Brentwood, I don't have the plug in to see the video. If you would, in words, why don't we (the outside observer) not see the contraction?

Otto

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PeterR280
Pooh-Bah

Reged: 05/27/13

Re: Scary relativity [Re: Otto Piechowski]
#6215994 - 11/25/13 07:59 PM

you have a very long perfectly stiff rod that reaches Mars. You tap out morse code before the light signal gets there.

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deSitter
Still in Old School

Reged: 12/09/04

Re: Scary relativity [Re: Otto Piechowski]
#6215998 - 11/25/13 08:04 PM

Quote:

I think I follow. The moon is moving at a near light speed so it "shrinks" in the direction of movement (perpendicular to the line connecting earth to sun). Since it shrinks, it should not cover the sun.

?

Otto

Yes, the eclipse happens, regardless of the state of motion of the Moon. This does not mean the Lorentz contraction is false - it means that the world is not 3D + time, it is 4D, and that new geometry has visible effects. That's what I am going to try to get across. Yes it is difficult, but as Kennedy said, we choose to go to the Moon, not because it is easy, but because it is hard!

-drl

 Post Extras:
EJN
Carpal Tunnel

Reged: 11/01/05

Loc: 53 miles west of Venus
Re: Scary relativity [Re: Otto Piechowski]
#6216003 - 11/25/13 08:10 PM

deleted

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deSitter
Still in Old School

Reged: 12/09/04

Re: Scary relativity [Re: EJN]
#6216009 - 11/25/13 08:15 PM

I hate to get off on a tangent but the length contraction is most definitely visible - it's just not a contraction in the naive sense of 3D space. The invariants live in 4D space, not 3D, and all direct reference to 3D space alone - which means all diagrams such as this - are misleading (a euphemism for wrong).

-drl

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brentwood
Carpal Tunnel

Reged: 11/04/05

Re: Scary relativity [Re: EJN]
#6216017 - 11/25/13 08:17 PM

The screen capture above shows it well. The previous shots are of the disk as it approaches us & light waves coming off various segments. It kind of made sense, but I'm still waiting to see how this ties in with those bloody headlights!
But I will be patient.

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deSitter
Still in Old School

Reged: 12/09/04

Re: Scary relativity [Re: deSitter]
#6216027 - 11/25/13 08:24 PM

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

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Otto Piechowski
Pooh-Bah

Reged: 09/20/05

Loc: Lexington, KY
Re: Scary relativity [Re: deSitter]
#6216039 - 11/25/13 08:33 PM

I believe I understand. Thank you guys.

Lesson #2.

Oh…what did the box matrix and trig have to do with this?

Otto

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deSitter
Still in Old School

Reged: 12/09/04

Re: Scary relativity [Re: Otto Piechowski]
#6216083 - 11/25/13 08:49 PM

We just got started. There is a long hill to climb.

-drl

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