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- OriginalReplica, on 04/10/2008, -4/+17This could be important, because if they do find gravity waves, then they can hopefully learn the real mechanics of how gravity works. Right now we about the effects of gravity, but not about how it actually does what it does. If we learn the how of gravity then we can learn to manipulate it, which will be a major step in allowing humanity to grow beyond planet Earth. Maybe planet Earth would be a lot healthier if there where only half as many people on it, because the rest had somewhere else to go live.
- BigManOnCampus, on 04/10/2008, -4/+16Looks like Michelson-Morley, only millions of times more expensive. Good luck guys! If you find the aether, do tell us how to ride it's waves.
- killbert24, on 04/10/2008, -2/+13So this is what Yoda means when he says, "I feel a disturbance in the force."
- Hangly, on 04/10/2008, -1/+11Einstein and I are still pretty confident that gravity is a property of warped space, not of particle exchange.
- HamsterOfDeath, on 04/10/2008, -0/+6They are trying to pick up deflections that are smaller than the wavelength of the lasers, smaller than the surface roughness of the smoothest mirrors, and much smaller than seismic disturbances. It's astonishing how much success they've had, and once one of these detects a major gravitional event, such as a black hole and neutron star collisions, these detectors will provide us with much more information than telescopes ever have.
- slicerace, on 04/10/2008, -0/+6The project is in no means simple -- they have had to isolate everything from vibrations. Cars, trains, everything that causes even the smallest vibration in the neighborhood of the facility can throw off the results. What they have been doing over the past several years is increasing the sensitivity of the experiment; they are now operating AT the design sensitivity, if I recall. I think that some of the frequency ranges are so sensitive that they are at the quantum shot noise limit. This is most definitely NOT a "rather simple project".
- iamaelephant, on 04/10/2008, -1/+6You fail at science and reasoning.
- x0rcist, on 04/10/2008, -2/+7Gravity gun anyone?
- inactive, on 04/10/2008, -0/+5LIGO Observatory video.
Easy to understand.
http://www.2.0web.tv/index.php?option=com_seyret&t ... - iamaelephant, on 04/10/2008, -0/+4This experiment isn't likely to give us a better understanding of how gravity works. In fact it is expected to confirm the predictions of general relativity, and if it does so it will not tell us anything we didn't already know. If for some reason it doesn't detect gravtiy waves then we would be looking at some new physics but this seems extremely unlikely considering how successful the theory has been in the past.
- BigManOnCampus, on 04/10/2008, -1/+5The force is an energy field that surrounds us, it is in all living things, it binds the universe together...
oh my god... gravity = the force. midichlorians = gravity control. - slicerace, on 04/10/2008, -0/+3Read the article:
"With the limited LIGO range at time, it wasn't guaranteed detection," said Albert Lazzarini, deputy director of LIGO at the California Institute of Technology. "With Advanced LIGO, it'd be very surprising from a relativity perspective if we didn't observe anything." - wrathchilde, on 04/10/2008, -1/+4OK, So Einstein said that if you *poof* take away the sun, the earth won't move from it's orbit for about 8 minutes (speed of light for 93 million miles). So, gravity travels like light. Quantum theory then wants a graviton (gravity particle that acts like a wave) to convey gravity force.
The outcome of finding gravity waves will either be to define gravitons, and move us toward a unified theory, or bust quantum theory apart. Not that there is anything wrong with that. - jakeybob, on 04/11/2008, -0/+31. Seismic motions will not lead to false positives. LIGO itself consists of three instruments, and is part of a larger worldwide network (VIRGO, GEO, other future instruments). A gravitational wave signal will appear in all detectors, localised seismic disturbances will not. Additionally, all detectors employ seismic attenuation systems that reduce residual seismic noise to acceptable levels.
2. LIGO (+ other ground-based detectors) and LISA will operate over different frequency bands, and detect different sources. LISA will not make LIGO redundant, but will instead complement it, in a similar way to how e.g. X-Ray astronomy complements optical.
3. LISA needs LIGO, in many ways. It'd be madness to send a mission into space before you knew the principles worked on the ground first. Once it's up there, it can't be fixed, so it's worthwhile knowing how to do everything before it goes! - pixeldust, on 04/10/2008, -1/+4ya dude, i bet they totally forgot about that. Or maybe that's the reason they have two separate facilities thousands of miles apart and have gone to incredible lengths to ensure the mirrors are stabilized.
- pixeldust, on 04/11/2008, -1/+3Uh, it would take the light 8 minutes to stop coming to earth and by the time we saw no light, and no gravity, it would be too late. So if the sun does disappear we don't even get 8 minutes.
- csrster, on 04/11/2008, -0/+2An argument isn't just contradiction.
An argument is a connected series of statements intended to establish a proposition. - undershirt, on 04/11/2008, -0/+2Dr. Brian Cox tries to explain gravity waves, but I don't get it.
http://youtube.com/watch?v=6EJ8r9Rhfw8 - gn0stik, on 04/10/2008, -0/+2The problem I have with this experiment is the logistics. How can one possibly make an experimental setup accurate enough? The mirrors have to be exactly the same distance apart. We're using light to measure the time differential, and at some point along the process we are using light to build the setup (visual adjustments, visibly measuring parts, etc.). Seems there would be a standard deviation in play that would cancel out the experimental results, and there would be no physical way we could ever build a device so precise as to overcome it, since the gravitational waves would effect the build of the experimental setup.
I must be missing something, because that's a lot of money to spend without being able to overcome such an obvious obstacle. - wrathchilde, on 04/10/2008, -0/+2Yes, that is so exactly it it's scary.
- infimprob, on 04/10/2008, -2/+4If gravity works just like particles at the quantum level perhaps we can find, and eventually harness a gravity containing particle. Damn that would be sweet, next stop portable wormholes.
- garryw, on 04/10/2008, -2/+4Gravity waves were predicted 100 years ago, they surely do exist, but not sure what proving that has to do with population density. Contraceptives is a more direct solution.
- inactive, on 04/10/2008, -7/+9Isn't science fun, kiddies?!! :-)
- Niightwitch, on 04/10/2008, -1/+3It's good to know we have that eight minute window in which to do something if the sun ever disappears.
- amesolaire, on 04/11/2008, -0/+2Pretty cool, thanks.
"Why isn't that obvious?" Really. Imagine a sound wave in air - it is an air pressure wave. Same thing with gravitational waves - "pressure" waves in space-time! - genepooldesign, on 04/10/2008, -1/+3Bob Lazar tried to tell the world about gravity waves, and no one believed him. Hmmmm.
- undershirt, on 04/11/2008, -0/+2Well, ether will have to do for now, since it makes the most sense to me. It may be technically incorrect, but I'm hoping it's correct by analogy. I'll take it with a grain of salt, thanks for your thoughts!
- duetosymmetry, on 04/10/2008, -0/+2The interferometer configuration is in fact Michelson-Morley, with some tweaks. Each of the arms has a Fabry-Perot cavity, which can be thought of as increasing the round trip time for light going down one arm, or effectively multiplying the length by the average number of bounces. Since the interferometer is designed to be operated with both arms the same length, most of the light in the arms interferes destructively out of the port away from the laser and constructively back towards the laser, so there is a power recycling mirror between the beam splitter and the laser. This acts like effectively multiplying the total laser power by the number of average bounces a photon gets off of the power recycling mirror.
Advanced LIGO will also be adding a signal recycling mirror which can be used to 'tune' the frequency-dependent response of the interferometer. - Olleces, on 04/10/2008, -0/+2Give me a portal generator any day.
- jakeybob, on 04/11/2008, -0/+2Measuring distances down to a thousandth the diameter of a proton != rather simple. Physicists have been trying to do this for 40 years, because it is absolutely *not* simple.
Additionally, while the parts may appear cheap superficially (and are certainly cheaper than numerous huge cryogenic superconducting magnets needed for particle accelerators etc) they are by no means inexpensive. A "mirror" is actually a large piece of the purest glass in the world, coated with ultra-low-loss coatings, suspended from the highly intricate seismic isolation platforms etc. A "laser" here means the some of the most stable and powerful cutom built lasers anywhere. Not to mention the huge vacuum technology, physical scale, data/computing infrastructure, control systems, electronics... etc etc. - duetosymmetry, on 04/10/2008, -0/+2pixeldust is partly right, but there is more:
The optics are suspended, which attenuates the component of ground motion noise at frequency f by a factor of 1/f^2 above the suspension's corner frequency for each suspension stage. In initial LIGO, the mirror suspensions are a single pendulum and the ground noise becomes irrelevant above about 40Hz. For advanced LIGO, the suspensions will be a triple or quadruple pendulum, and the goal is to make ground noise irrelevant above ~10Hz.
By comparison, the peak sensitivity of the instrument was more or less designed to be the sweet spot for a binary neutron star inspiral, which ends (and is loudest) around ~150Hz. - undershirt, on 04/11/2008, -0/+2Yeah, ok, pressure is a good way to put it, thanks. Pressure applies to space, but I don't see how that also applies to time, since he said the waves disturb space-time. I guess I just don't understand how space and time form a connected fabric.
- inactive, on 04/10/2008, -0/+1Access and amplify these and they can power my UFO
- Beanbones, on 04/10/2008, -0/+1You all miss the biggest benefit of understanding the "how" of gravity - finally being able to shut up those Nibiru idiots once and for all.
- forgiste, on 04/11/2008, -0/+1If only George Lucas were that smart...
- humperdeath, on 04/10/2008, -0/+1Duuuuude! Totaly can see myself hanging one these waves!
- inactive, on 04/12/2008, -0/+1density and not a wave.
- rrouse, on 04/11/2008, -0/+1We need to make public our Black Budget research in reverse engineering ET craft because at least some of them work by controlling gravity.
- hollyminkowski, on 04/10/2008, -1/+2Gravity is really interesting.
What is especially odd is how incredibly weak it is compared to the other basic forces, electromagnetism, weak nuclear force and strong nuclear force. - pixeldust, on 04/11/2008, -1/+2Which is why I'm talking about LIGO.
- inactive, on 04/12/2008, -0/+1Gravitational waves could conceivably move instantly, or separation is an illusion
http://www.youtube.com/watch?v=6Dq454iFp2c
I tend to go with the first. - amesolaire, on 04/11/2008, -0/+1Isn't the difference in the speed of light the expected _effect_ of the irregular density of the "ether" (ether wind)? Ultimately they were trying to establish the presence of "ether wind", and the difference in the speed of light in different directions was the means to do that (at least they thought so), not the objective of the experiment.
- sriel, on 04/11/2008, -0/+1It's like an ocean with continuous, random, average waves from every direction, the setup is calibrated on this ocean. Once in a while there will be a very large freak wave produced by a rare cosmic event, this wave will deviate from the randomness.
- amesolaire, on 04/11/2008, -0/+1Actually, pressure applies to substance, not space, but I understand your frustration with not being able to visualize the time aspect of space-time. I can't either and probably few people can. This is why when it comes to relativity, I prefer to think in terms of ether, and substitute time dilation for (irregular) ether pressure. Seems to me that both concepts would manifest themselves in the same observable effects. Then a gravitational wave becomes just an ordinary ether pressure wave. Gravitational lensing - light refracting in ether. Everything seems much more intuitive when you think in terms of ether. Too bad it's fallen out of consideration in modern physics.
Btw, don't take advice on physics from me, I'm not a physicist. I was just expressing my sympathy, and then went off on a tangent. - BigManOnCampus, on 04/10/2008, -0/+1My comment *was* slightly tongue-in-cheek. I realize it's not exactly the same.
- Niightwitch, on 04/10/2008, -1/+2principle
- iamaelephant, on 04/10/2008, -1/+2The principal is very similar, they are both interferometers designed to measure slight differences in travel time for light.
- InferiorWang, on 04/11/2008, -0/+1It depends on how common said gravitational waves are. If they are fairly common, then they may influence development of the setup. If the waves are relatively uncommon, then such a setup should be feasible. However, technology regularly makes the infeasible feasible.
- jakeybob, on 04/10/2008, -0/+1But for opening up an enitirely new spectrum to observe the Universe...? Nobel Prize, I think so.
Also, Hulse and Taylor were awarded the Nobel Prize for binary pulsar observations that implied gravitational emission in 1993 - and that was only indirect measurement on a single source. - Intercon, on 04/11/2008, -1/+2Manipulation of gravity is believed by many to be the next evolutionary step from planet-bound to intergalactic and beyond for the human specie. Everything from folding space for faster than light communications and travel, mass transit on a planetary scale, personal anti-gravity protection devices, force fields, and some very interesting engines, would all be possible from the technology that would naturally develop once gravity manipulation is refined. IF that is how gravity works, and we can begin to see how to use energy to create fields within the Earth's field of gravity. I'd say it's a small price to pay for the advancement of all mankind (if it can manage to get it's collective head out of its ass and save itself.)
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