

What Neil & Buzz Left on the Moon (Other Than Footprints) - diwank
http://science.nasa.gov/science-news/science-at-nasa/2004/21jul_llr/

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diwank
A very interesting example of relatively lesser-known scientific innovations.
It is a surprisingly rare knowledge. In fact, it is one of the evidences
scientists use to refute the claim of the moon-landing deniers.

It is also worth mentioning that this project has now been axed (in 2009 to be
precise) as the mirrors have gotten dusty and no longer provide the same worth
of scientific data they used to [1]. The above post was written in 2004, long
before such problems surfaced.

[1]: www.guardian.co.uk/technology/2009/jun/21/mcdonald-observatory-space-
laser-funding

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Yhippa
This was mentioned in the article: "But Einstein, constantly tested, isn't out
of the woods yet. Some physicists (Alley is one of them) believe his general
theory of relativity is flawed. If there is a flaw, lunar laser ranging might
yet find it."

Does anybody know what specific flaw(s) they're talking about?

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diwank
A scientific theory is a set of principles that explain and predict phenomena.
All theories are only provisional, in that they are upholded every time an
observation supports the predictions they make. In principle, a good
observation that is inconsistent with a theory's prediction can falsify it.

In this case, Einstein's theory predicts the lunar orbit to be slightly
different than Newton's gravitation model. If someone could find a discrepancy
in new observation he would have found a flaw in Einstein's theory of general
relativity.

As of this writing, no flaws have been found in the theory of general
relativity. Though such claims pop up every now and then.

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drcube
What do they mean when they say the gravitational constant has changed less
than 1 part in 100 billion? Surely that's within experimental error? I think
they mean to say "there is no evidence that it has changed at all".

