So, basically, one of them's in a place CALLED Chile, and the other is in a place THAT IS chilly!!
International brainboxes operating a fiendishly cunning probe contained in a small rotating shed on a pole situated in the arid high-altitude desert of Chile are in a race against rival boffins with a telescope on stilts at the South Pole to discover how the universe was born. The two crews of elite brains are looking to …
First a disclaimer, while this type of stuff fascinates me, I’ve not got any scientific understanding other than documentaries, books and the interweb. If anyone with more understanding wants to post with explanations or useful links, please feel free.
Gravity waves. The mental image I get it one of throwing a rock in a pond. As the ripples expand out from the source, they decrease in frequency and amplitude. Surly it’s possible that if our instruments and we are sufficiently far away from the source, the frequency and amplitude will become so faint as to require measurements over many years or centuries or longer with highly accurate equipment. If this is possible, what hope does either experiment have of succeeding?
Also, what about more local events like super nova? They must also generate gravity waves, but on a much smaller scale. For instance, gamma ray bursts worried scientists because it looked like the energy they where emitting was greater than Einstein’s e=mc2 equation. That was until someone said that the bursts are emitted in an hourglass shape. Which must also mean that we can only see a fraction of the gamma ray events. Again, I think of a pond, this time not still, but having an unimaginable amount of tiny bubbles popping on its surface. Now when I throw the rock in, the ripples I cause don’t travel as far because of the cancelling effect of all those little bubbles bursting. If my analogy holds true, that would make the task even more difficult.
Thanks for reading, hope you did not find it dull!
Er, silly question, but why two 'teams'? Wouldn't pooling their resources and funding produce one really, really good scope instead of two rush-jobs?
Oh, they're humans, right, carry on.
Mine's the one with the electronic-sub-etha-signalling-device, trying to get off this horrid little planet.
They ent detecting gravity waves directly - they're looking for the effects that this primordial space-time wibbly wobblying would have had on the cosmic microwave background radiation, a la COBE.
It should see hot spots where the waves are in compression, and cold bits where they stretched space (well, relatively - it was all being stretched humunguosly; the gravity waves just overlayed a little extra squishing and stretching on top).
Presumably, their awesome theory predicts a particular pattern of hot and cold, rather than just a bunch of random speckles ?
They're looking for a particular pattern in the polarization of the CMB (at very low brightness and small angular scales). The idea is that the dominant "wobbles in the jelly" are spherically symmetric - think of a very big jelly in empty space starting to fall in on itself under its own weight and then springing back. However gravitational waves do something weird - if you pass one through the jelly, it'll shrink first along one axis, and then along another axis. Now, light passing by a lump of plasma that's wobbling becomes slightly polarized, and if it's wobbling gravitational-wave style, the orientation of the planes of polarization make a characteristic pattern that you don't get from regular wobbling.
Counter-intuitively, the hot spots in the CMB correspond to the less dense patches - light coming out of the dense patches gets gravitationally redshifted.
@Adrian: There are many very good generic scientific reasons for having several experiments make the same measurement. Can you not think of any? And I'm sure the teams involved in these experiments who have spent many years developing them and will spend many more analysing the data would be mightily disabused to hear you call them "rush-jobs".
Cheers, folks, you're welcome - I guess it means I can put "Arseing around on t'internet" under Public Outreach Activities in my next grant application :)
Coincidentally, Pad, I went to a very good talk yesterday about LISA, the planned gravitational wave detector in space. The speaker showed a plot of the instrumental sensitivity which made the same point as your analogy with the bubbles popping in the pond. Primordial gravitational waves down the bottom at low amplitude, and a huge swarm of "louder" green dots drowning them out - the green dots mainly being white dwarf binaries within the Milky Way with a period of a few hours. Direct detection of primordial GWs may be a long, long way off...
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