Monday, May 09, 2005 ... Deutsch/Español/Related posts from blogosphere

LIGO 2nd run: no waves

The LIGO collaboration informed that the second science run did not detect any gravitational waves. The results follow from 10-day-long observations in early 2003 (two more science runs have been made ever since):

Quantitatively speaking, the number of signals at frequencies 100-1000 Hz that are shorter than 1 second and stronger than about 10^{-19} (amplitude of the metric perturbation) is smaller than 0.26 per day at 90 percent confidence level.

Some of their statistical methods to search for a signal look pretty fancy. The bounds have been improved. Only the signal is missing so far. Mother Nature is able to be as cruel as She was co-operating in the past...

Before someone is gonna blame Kip Thorne et al. for having wasted 365 million USD (the most expensive project ever funded by NSF), you should know that virtually all theoretical physicists have very good reasons to be convinced that the gravitational waves should exist, they should be visible by LIGO a bit later, and once we can detect them with some accuracy, they can tell us a lot of things about the universe.

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reader Quantoken said...

Any one who has the slightest hope of LIGO detecting any gravitational wave due to remote astromonical events, like supernovae, clearly does not have a decent sense of order of magnitude.

If you have the basic elementary arithmatic skill, you should be able to do a simple calculation and answer this question:

Which one of the following has the weakest gravitational pull on the LIGO detector, or generate the weakest of gravitational wave at the location of the LIGO detector, and which one is strongest?

1.A small ant crawing just one meter away from the detector sensor.

2.A lumber truck driving on the other side of the earth.

3.A supernovae exploding only a million light years away, or in a neighboring galaxy.

The answer is the ant, the truck, and then the supernovae, but in the order from the strongest to the weakest, with the supernovae signal almost a billion times weaker than that generated by the ant!!!!!!

If the scientists of LIGO have not noticed that there are ants crawing nearby, or that there are a couple billion trucks driving around the earth, then how could there be any hope at all detecting any gravity wave from supernovaes, regardless how sensitive they can make their instruments.

Quantoken


reader Your Psychiatrist said...

Quantoken,

I can't resist pointing out the flaw in your rambling argument: They (LIGO) Fourier transform the signal and filter out the (low frequency) noise due to trucks etc. In the frequency range of interest (couple 100Hz or so) there are no competing disturbances of the sort you mention.

That said, your "arithmatic" skills are indeed at most basic, while LIGO is operated by some fine experts. Why don't you start "crawing" back to your own blog?

And see me for some more medication. Tomorrow!


reader Arun said...

Lubos, any comments on
http://xxx.lanl.gov/abs/gr-qc/0412068