Frame-Dragging Clearly Visible | Hacker News Reader

Frame-Dragging Clearly Visible

einstein.stanford.edu

49 pointsonoj12 comments

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.

Not a lot of context in this announcement.

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

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.

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?

Deep in your heart you know earth is flat.

People don't care as much when trillions of dollars, their own prosperity, and/or certain doom aren't seemingly hanging in the balance.

The question then becomes how do you define what appropriate corrections are & what is fudging the data?

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.

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

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).

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!

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).

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