

Frame-Dragging Clearly Visible - onoj
http://einstein.stanford.edu/highlights/hl_111209.html

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KevBurnsJr
My dad is a thermal dynamics engineer at Lockheed Martin. He helped design the
Dewar for the payload. The Dewar is a giant thermos containing enough liquid
helium to keep the satellite's sensitive instruments cooled to below 4 degrees
kelvin for the duration of the experiment (1 year).

<http://einstein.stanford.edu/gallery/dewar/dewar_lift.jpg>

The team had a bet going on how long the satellite would be able to record
meaningful data while in orbit. He won the pool after guessing correctly to
within +- 24 hours on the year-long mission. This is my dad on the left :

<http://einstein.stanford.edu/Library/images/He_dep-MOC-1.jpg>

Like jmillikin says, the science team collected terabytes of data and ran over
several deadlines to report their findings. The precision required for the
experiment is really quite phenomenal. Measuring discrepancies in gyroscopic
alignment to within the 4 marcsec/yr is not trivial.

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chaosmachine
Not a lot of context in this announcement.

<http://en.wikipedia.org/wiki/Frame-dragging>

~~~
jmillikin
See <http://en.wikipedia.org/wiki/Gravity_Probe_B>

The spaceflight section of this experiment ended a few years ago, but there
were major unanticipated problems with the recorded data. Stanford figured out
where the errors were coming from, but correcting them requires time-consuming
computer simulation.

This announcement means that they've figured out and compensated for enough
noise sources that the signal is becoming visible, and it's within a decent
margin of error of what they expected.

Analysis is scheduled to continue on into 2010, but this is great news.

~~~
seldo
I can't help but remember all the fuss a few days back from the UEA scientists
applying corrections to their own climate change data.

These guys spent years coming up with complex modifications to the raw data in
order to match the frame-dragging they were expecting to see. Are we going to
accuse them of falsifying data and bowing to political pressure too?

~~~
eru
Deep in your heart you know earth is flat.

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idlewords
Obtaining this result cost us about a billion dollars.

I'm as excited about confirmations of General Relativity as the next person,
but when you think about the kinds of non-trivial planetary science or
cosmology experiments you could fire into space on a billion-dollar budget,
the decision to throw dollars at Gravity Probe B (not to mention the ISS...)
is regrettable.

~~~
eru
At least they did not put humans on the Gravity Probe B.

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swolchok
Can we have a title on this that indicates that it's physics, not tech,
please? I wouldn't have clicked if I had known it was physics.

EDIT: um, I'm not commenting to complain that the post is on HN; I'm
commenting to complain that the post is on HN with a title that makes it look
like it might have to do with computers (e.g., windowing systems or frames in
web browsers).

~~~
drunkpotato
I like physics, but as a layman I have no idea what they are demonstrating.
(Something to do with relativity, got that...) A little background information
would be appreciated!

~~~
idlewords
One of the predictions of General Relativity is that a spinning massive body
will drag neighboring spacetime along with it - that is, impart a bit of the
spin to anything nearby. See <http://en.wikipedia.org/wiki/Frame_dragging>

This is a very subtle effect if you don't have a neutron star or black hole
around, but using gyroscopes built to crazy tolerances, this experiment
appears to have demonstrated it (at a head-spinning cost).

