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Author Topic: How were plate tectonics distinguished from Earth just getting larger?  (Read 2249 times)

Offline Spacetectonics

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Hang in with a geologist ;it takes Him/Her "a geological time" of millions years to understand science!! :o
I am one of them!

Supposed you are standing on the edge of African plate (continent) and you are observing South American continent (For now consider a flat earth!)And imagine the speed of these two diverting plates is far above their scientific regime (let’s say 600 KM/s instead of xx.xx millimeter per year).

As an observer you could measure the redshift effect arriving from the South America plate (Tower light) and based on this observation you figure out that this continent is going away from you.
Now you wish to consider and announce a scientific result for your observation, to do so you have very limited tools and you could not map the entire earth either!

Under above conditions the most reasonable assumption could be “expansion of the planet earth”.
Considering that you could not map from the sky or the interior of the Earth (4th dimension!!) or reaching South America .

What do  you consider to present you statement ,scientifically correct about this issue!!?

http://en.wikipedia.org/wiki/Universe_expansion
 ;)
« Last Edit: 19/12/2012 15:12:29 by chris »


 

Offline imatfaal

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surely the most reasonable explanation (via occam) is that there is a relative velocity between Africa and South America - the earth expansion as an explanation would require further data.

That further data would be observations that every unbound point measured is moving away - and that the speed of the movement is directly proportional to the distance of the object.  It is those two additional facts that lead to Hubble's law and why universal expansion is the best explanation of the observed facts.
 

Offline Bill S

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If, looking from Africa, you could see two points in S America, that were at different distances from you, you would observe that they were receding at the same rate; thus you would know that the cause was not expansion in the cosmic sense.  Of course, the Earth could be expanding along plate boundaries, but that would be a different matter.
 

Offline Spacetectonics

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you would observe that they were receding at the same rate; thus you would know that the cause was not expansion in the cosmic sense.
Thanks Bill S,

Could you open the above please? I guess you mean "when we look at a galaxy we see two points receding at two different rates?!"
Cheers
 

Offline Bill S

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Quote
I guess you mean "when we look at a galaxy we see two points receding at two different rates?!"
 

I'm neither an astronomer nor a cosmologist, but my understanding is that different recession rates would be observed on the scale of galaxy groups.  On that scale, recession rate increases with distance in a regular way that would not be the case with tectonic plates.

 

Offline CliffordK

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A 2 dimensional surface map, and 3 dimensional space may have different control factors.

As the Atlantic slowly expands, the Pacific slowly contracts.

Unfortunately, the visible universe which we can see is likely only a small portion of the entire universe.  And, it is unclear where we would be in the entire universe, in the middle, or near an edge, or even how large the unseen universe is.

One option would be a very large scale type of stretching/contracting vibration in space, in which the wavelength is greater than 26 billion lightyears, and some parts of the entire universe is expanding, while other parts are contracting.  Even still, it would be pretty extraordinary that everything we can observe would be in the expansion phase, and generally at the same rate, if there were in fact other parts of the universe out of our view that were contracting.
 

Offline Bill S

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Quote from: CliffordK
One option would be a very large scale type of stretching/contracting vibration in space, in which the wavelength is greater than 26 billion lightyears

Presumably, if this were the case, the rate of expansion/contraction would vary with some regularity across each wave, so the wavelength would have to be much greater than 26 billion l y to avoid our being able to detect it.
 

Offline Spacetectonics

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A 2 dimensional surface map"

Respect but plates are not 2 D!

 

Offline Spacetectonics

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And have you ever wondered why "space-expansion"is only happening between galaxies??! not inside them? just like plates of the earth?(except the inner-continental rifts)

 

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