Thursday, January 26, 2012

Q: How can gravitational waves help mankind?

UPDATE:  [11 Feb. 2015] Gravitational waves have been detected!  Read more about it here.

@HughScot asked:
What do you hope to discover about gravitational waves that will help mankind in the future?
There are many things that we hope to observe through gravitational waves especially since they have the advantage of being able to travel through matter and come out the other side unchanged, unlike the different forms of light used in traditional astronomy.  This gives us the opportunity to observe things that do not emit light, like black holes or to observe systems that would otherwise be obscured by intervening material.

But this question asks how gravitational waves will improve mankind in the future - as in what are the applications of gravitational waves.  I get this question often when I am giving tours of the facility.  Well, the primary use of gravitational wave observations will be to understand our Universe better.  Most people's reactions to this are that our efforts can better used for other endeavors.  But this view is a little short sighted.  One of the things we forget is that when we understand more about the Universe in general, we know more about the world around us.  We are a very small part of the Universe, but we are a part of it nonetheless.

One of the direct uses for gravitational waves will be to use them to turn the Universe into our own laboratory.  There are many things that we cannot replicate on Earth, like the dense cores of neutron stars.  Under extreme conditions like this, nuclear physics and thermodynamics can theoretically do some interesting things.  However, we can't investigate those directly because we cannot create these environments ourselves.  That's when we turn to the Universe for our laboratory!  Prime candidates that will allow us to use gravitational waves to investigate this include pairs of neutron stars merging into one star, starquakes on these stars, or even rapidly rotating neutron stars with "mountains" on them (and I put mountains in quotation marks because neutron starts are believed to be so perfectly spherical that a deformation a few millimeters [a quarter of an inch or so] is 'huge').  Knowing the details of how nuclear physics and thermodynamics changes in these environments can have applications on Earth, although I can't tell you what they are yet.

Another application of gravitational wave observations will be testing Einstein's general relativity.  Even though gravity is the force that holds the Universe together, we have a very difficult time testing it since it since it is also the weakest force in the Universe (there is no negative mass to cancel the effects of positive mass like happens between positive and negative charge).  Since the mass needed to conduct experiments to test general relativity is so great, lab experiments are very few.  Again, we must turn to the Universe to be our lab.  Directly observing gravitational waves with LIGO and detectors like it will allow us to perform tests on general relativity that we have never been able to before.  For example, it is expected that gravitational waves travel at the speed of light but there really isn't anything in the theory that constrains them to that speed (they could travel slower).  Detecting gravitational waves with multiple detectors across the planet and observing light from the same source in the sky would allow us to test this.  (By the way, even though general relativity is difficult to test, every time it has been tested it has proven to be right!)

We already use an application of general relativity in our everyday lives: a consequence of special and general relativity is that time passes a different rates based on the speed of an observer or the strength of the gravitational field that the observer is in.  No matter what, your time will always be the same, but you may observe the clocks of others who are at rest or traveling slower than you ticking slower than yours (this tutorial does an excellent job of explaining how this time dilation works).  If corrections for this effect are not taken into account, the clocks on GPS satellites would quickly become out of sync and the GPS in you car, etc. would not be able to accurately locate you!

Besides the benefit to mankind due to the information the gravitational waves themselves will bring us, we have also developed a significant amount of new technology to make LIGO work.  We have developed new seismic isolation techniques that allow less than 1 billionth the energy of normal ground vibration into our instruments, we have required and received the most precisely polished mirrors, and we have developed new suspension and control systems to stabilize our optics.  These are just a few of the advancements the search for gravitational waves have made.  I am sure that there are many other applications for these new developments (although I haven't explored them myself).  Using technology developed for other purposes is a well known phenomenon in science and technology call spin-off technology.

In conclusion, we will never be able to commercialize or weaponize gravitational waves themselves.  However, they will carry information to us about some of the most extreme environments in the Universe which we can use as a laboratory for environments we cannot create here on Earth.  This information can tell us more about how the physics around us works in subtle ways that can have profound implications.  What those are are yet to be seen.  That's the exciting thing about science - you never really know the full potential of new discoveries until after the fact.


Today's picture is of an engineer (my husband Derek Bridges) dressed in clean room garb (so as not to contaminate the equipment that will be placed into LIGO's interior vacuum).  The blue stands he is leaning on are part of the seismic isolation system mentioned in the text above and the big steel chamber behind him is one of the many used to contain LIGO instrumentation in its vacuum.  This picture was taken at the Advanced LIGO testing lab at MIT.

I hope this answered your question!  If not, please feel free to ask me more about this or anything else!

21 comments:

  1. I understand that finding out about gravitational waves will help us find out about the universe and can be applicable to the earth but can you tell me more about what you are actually doing with the gravitational waves or how your observing them to get the data your trying to get? In other words can you explain some of the experiments you would do in order to get more information on neutron stars.

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    1. This is a great question which I would like to see answered too. AFAIU, one of the most important measurements relating to general relativity would be the relationship between the amplitude of the waves measured and the orientation of the source compared to the detector. Unfortunately, I believe this may be very difficult to measure, because the gravity waves measured would have to be matched to a specific optically observable object.

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    2. Another interesting possibility (note I have absolutely no qualifications in this domain) would be to measure gravity waves from the beginning of the universe. This can be roughly compared to the cosmic microwave background which comes from a few hundred thousand years later when the universe became transparent to light. With gravity waves we could potentially measure conditions right up to the "big bang".

      However, again, (based on my extremely limited understanding), getting a useful "image" of this would be incredibly difficult, probably a couple orders of magnitude more difficult than the orientation measurement I mentioned above. My guess is this would require many detectors in multiple orientations and spread over a great distance with very precisely synchronized clocks.

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    3. If possible also chk is there any increase or decrease in the intensity of waves within a month or year's time. This will provide us answers to how long the Mother earth can survive. And how we can increase longevity of earth.

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  2. Can this discovery helps us reach the boundaries of the universe and determine the shape of our universe?

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    1. It seems possible right? If the fluctuations from immediately after the big bang are actually measurable by our gravity waves detectors (see my above reply to Steven Cale), and we build a whole bunch of detectors at different orientations and distributed through a large volume of space with very synchronized clocks, it seems we should be able to collect information about the distribution of mass throughout the observable universe.

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  3. I wonder kind of communication device we can build, may be in the future this discovery will help anyone make a call to the past and the future.

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    1. There is no expectation that gravity waves traverse time. Note in the article that they are expected to travel at light speed.

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  4. Read "The Hole Man", a short story by Larry Niven. It is available in many libraries in the anthology _A Hole in Space_, or on Amazon Kindle. Niven is a well known hard science fiction writer, and won the Hugo Award in 1975 for this story.

    In this story, Niven's characters discover a gravitional wave communication device on Mars, left by an alien race. The device contains a quantum black hole in its center, which carries a charge that allows it to be vibrated by electromagnetic fields to produce modulated gravitational waves for long range communications. It is a pretty interesting application of the concept.

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  5. Can this new discovery help us also in our daily lives, technology usage etc ?

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  6. Are there possibilities of using gravitation waves in the study and prediction of earthquakes?

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    1. Unlikely, gravitational waves are created from asymmetrical objects with immense gravity spiralling and earthquakes are from the heating and cooling of magma in the earth's core.

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    2. Unlikely, gravitational waves are created from asymmetrical objects with immense gravity spiralling and earthquakes are from the heating and cooling of magma in the earth's core.

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    3. Unlikely, gravitational waves are created from asymmetrical objects with immense gravity spiralling and earthquakes are from the heating and cooling of magma in the earth's core.

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    4. Unlikely, gravitational waves are created from asymmetrical objects with immense gravity spiralling and earthquakes are from the heating and cooling of magma in the earth's core.

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  7. Thanks Abram Clark for enlightening us on the application aspect of the latest sensation the gravitational waves. I do agree with you. But how far we will be able in its conversion into different forms of energies. Moreover what are the future extension of the detection, does it happen only when the black holes collide or there any inventions in pipe line?

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  8. Two questions: First, is it possible to localize the source of gravitational waves?

    Second, what do these experiments tell us about gravity that we didn't already know? In other words, aren't gravitational waves kind of obvious? I mean in the sense that we know that the gravitational pull form an object is greater near the object, so in the case of two black holes circling each other (i.e. moving closer and farther from a sensor on Earth) our traditional model of gravity suggests that the intensity of gravity should oscillate. So why build equipment or facilities to listen for these phenomena?

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    1. Actually I found that there is a very good discussion that answers these questions here: http://physics.stackexchange.com/questions/235248/why-is-the-detection-of-gravitational-waves-so-significant

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  9. I suppose the expected proof of antigraviton will come out someday. Répulsion out of my home gravitational field,up, up and away is what i am waiting since i witnessed my 1st & only UFO a while ago...

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  10. Is it possible to go in future through gravitational waves?If there are two blackholes circling inside so,which one have greater gravitational power?

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  11. I think it is possible to deduct the existence of graviton from this discovery.

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