Why wouldn't we start S6 search right now?
11 Aug 2007 5:37:39 UTC
Topic 193032
(moderation:
We anticipate to receive high quality signals from highly relativistic objects as often as once per day with Advanced LIGO instruments, placed instead of curent. So, why not to start this improved search right now? Why we have to process a rought enough data before we could start main search. This was supposed from the beginning that S3, S4 and S5 search will not find any evidence of gravitational waves. So, that's look like we are just looking for neutron stars, block holes e.t.c. this time and not realising our main aim.
I know we already know enough highly relativistic objects that we can look at thoroughly. Why just not to do this right now to reach the main point from the beginning? Please, who really knows what quantum mechanics is and how this project works concretely, please try to explain me. Otherwise, I don't understand what we are doing right now and what for?
Why wouldn't we start S6 search right now?
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I think you could visit the LIGO,GEO600 and VIRGO sites to find an answer to your questions. But the project main aim has little to do with quantum mechanics and more with general relativity. As you probably know, these two great theories are still uncorrelated, many efforts notwithstanding. To unite them would be a dream of every physicist and also a tribute to the monk who said "entia non sunt multiplicanda praeter necessitatem" (Wilhelm of Ockham).
Tullio
Basically, there are lots of
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Basically, there are lots of exciting new theories which, as Tullio alluded, attempt to reconcile quantum mechanics with general relativity, like String Theory and Super Symmetry, to name a couple. And then there are ideas about the structure of stars, including things like elastic or magnetic mountains. The gravitational wave interferometers have been constraining the limits to these ideas and theories with every new science run. The more you check, the more fascinating it is! And it's also important to keep in mind that observational probabilities are greatly enhanced by the total amount of time accumulated during operation, since some types of events are expected to occur only rarely as it is...
RE: snip... To unite them
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Is that where the term "Ockham's razor" comes from?
-edit- and right after I posted this I asked myself why I didn't try a little research and answer my question myself. I'm getting lazy... nm, I'll figure it out.
RE: RE: snip... To unite
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Exactly. It IS Ockham's razor.
Yes, you all are right about
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Yes, you all are right about quantum mechanics and general relativity. I'm trying to stay in time with any news about this. Sometime ago I've finished reading Steven Hocking books about these new theories you are talking about.
But the main question still remains: why couldn't we start most sensitive search right from the beginning? Why only just now, after 3 years of hard work of a half world? I understand, the we should test instruments, upgrade them.
Just imagine yourself, if it would be not a distributed computation project and our project coordinators have to buy a computer time on supercomputer for example in Los Alamos. Than this project would be closed right after opening, not for it's just too expensive, but nobody will compute anything on supercomputer just to tune up instruments. But we, all participants of Einstein@home, do.
May be I'm wrong, but this conclusion came out right from S3 research report (look at the link on the main page). So... does anybody know what we (Einstein@home participants, not LIGO,GEO and VIRGO engineers) do right now and what for?
RE: Yes, you all are right
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I think one reason is that pulsars are good candidates for sources of gravity waves. Mergers between black holes and/or neutron stars within range of the interferometers probably do not occur very often.
Another reason is that you have to crunch the data from one run before you can begin making comparisons to data in the next run. The interferometers produce the best data possible, but pushing the boundaries is always a learning experience, and the data simply has to be crunched to learn from it.
edit: I think you mean Stephen Hawking :)
RE: We anticipate to
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S6 is not Advanced LIGO. Advanced LIGO will start observation in 2013. In the meantime it would be a sin to dump the current S5 data without any analysis.
As far as I understand it (please correct me) the reason to limit Einstein@Home to a search for Pulsars as GW emitters is that unlike other sources (inspiraling binaries, black hole mergers, super novae, background GW radiation ....) aspherical neutron stars should provide
a) a fairly predictable waveform (only few parameters to guess)
b) over a long time
c) in a frequency band that is within the optimal sensitivity of LIGO and GEO.
While the signal itself might be weaker than that from other sources, it can be amplified mathematically by "integrating" it over a long observation time.
I think the way to look at it is that the current search will give a useful result in any case: either some evidence of gravitational waves, or a new, better, upper limit that tells us that if GWs of the kind we are looking for really do exist, they must be weaker than the current observatory sensitivity. This would be a valid result as well, and the best we can do until Advanced LIGO and LISA are up and running, I guess.
BRM
Yes, again. We will
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Yes, again. We will understand better whether GW exist or not. But...
I have a simple suggestion that comes to my mind right when I're read your posts. So, we are looking for signs of weak interactions just like we are looking for distribution of HydroGen in universe (just what Seti@home do really instead of looking for extraterrestrial intelligence). But we can simply predict the form, the shape and the factor of the signals we are looking for.
We have gravitational interactions right here in our solar system (between sun and huge planets for e.g.) that we can measure (using Newton mechanics). I understand that weak interactions are extremely smaller and we can't register them. But we may imagine for e.g. the measure of interaction between sun and Jupiter as 1 (the measurement doesn't play any role this time) and extrapolate this on any other model from Big Bang to Supernovae explosion just using mass proportions (I suppose, the mass of interacted bodies is the main component in gravitation equations). Rigth after that we can imagine the magnitude of the expected GW and conclude whether our instruments just sensitive enough to sense these waves or not in this time). I think that something goes wrong because we haven't find any source for about 2 years. This may be because of weakening the signal over the time-space, or because our instruments are too rough to find them. I thing (it's like simple eye-glasses) that we have to see the "light" to tune up instruments to look at it better. Right now we don't have any evidence of GW, except that the theory predicts. Am I right?
S5 will end on Sept. 1, or
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S5 will end on Sept. 1, or Oct. 1, or Nov. 1. It depends on the readiness of Enhanced LIGO. It goes like this: S5 ends, then there is one month freeze while they make calibration/postrun measurements on the IFO, then they commission Enhanced LIGO ~ 18 months (factor of about 2 improvement in sensitivity, or 8 in volume and hence rate), then they run S6 out to the start of 2011. At ~2011, shutdown for Advanced LIGO installation, ~3 years, come back online 2014, commission X number of years, gain of factor of 10-15 in sensitivity, the cube of that in rate, and then ... some 40 events per year of binary neutron star inspirals ... is the belief.
_dan
I think VIRGO has started its
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I think VIRGO has started its first science run. See www.virgo.infn.it. I don't know if these data will be available to einstein@home,but I hope so.
Tullio