Well, it is what I research (at least tangentially), so I thought I would open up a thread on it.
First off, what is a gravitational wave? If you imagine that information cannot immediately, than you can conclude that if the sun disappeared, it would take some time for that information to reach us. More realistically, if you have two fairly large objects orbitting each other, say two black holes, then as they continuously get closer and move away from us we feel stronger-weaker-stronger-weaker pulls, but it takes some time for this information to reach us. That is a fairly simplistic description, I hope it makes some sense.
A couple of guys won a Nobel prize back in 1993 for discovering a binary neutron star system (well strictly speaking, a binary pulsar) whose orbital period (the "year" of the system) was decreasing. This is equivalent to a loss of energy and the energy lost by the system as measured coincided extremely closely to the theory of general relativity. This provided indirect proof of the existence of gravitational waves.
The quest then began to directly measure the gravitational waves. The problem: gravity is incredibly weak. Now being pulled down onto the surface of the earth, this might seem like a silly statement. However, the gravitational pull between two protons or two electrons is much less than their electrical repulsion/attraction. For this reason it is very easy for us to produce electrical waves (light, radio, microwave, uv, so on) but terribly challenging to produce gravitational waves.
For this reason, we need huge "antennae"; in fact, huge laser interferometers. These also cost a lot of money. To get some idea of the challenge, these interferometers are looking for changes in length which are smaller than atomic radii between two ends of the laser interferometer which are separated by about five miles. The smallest vibration in the mirrors can completely spoil all hope.
Why do we care? Well, we would like to see black holes, for starters. By definition, black holes are not visible, but by detecting the gravitational waves they produce, we will be able to pinpoint their location, masses, spins, speed, and that is all it takes to describe a black hole. Moreover, we will be able to learn about the structure of neutron stars and matter at extremely high density.
In the meanwhile, we produce pretty movies and hope.
First off, what is a gravitational wave? If you imagine that information cannot immediately, than you can conclude that if the sun disappeared, it would take some time for that information to reach us. More realistically, if you have two fairly large objects orbitting each other, say two black holes, then as they continuously get closer and move away from us we feel stronger-weaker-stronger-weaker pulls, but it takes some time for this information to reach us. That is a fairly simplistic description, I hope it makes some sense.
A couple of guys won a Nobel prize back in 1993 for discovering a binary neutron star system (well strictly speaking, a binary pulsar) whose orbital period (the "year" of the system) was decreasing. This is equivalent to a loss of energy and the energy lost by the system as measured coincided extremely closely to the theory of general relativity. This provided indirect proof of the existence of gravitational waves.
The quest then began to directly measure the gravitational waves. The problem: gravity is incredibly weak. Now being pulled down onto the surface of the earth, this might seem like a silly statement. However, the gravitational pull between two protons or two electrons is much less than their electrical repulsion/attraction. For this reason it is very easy for us to produce electrical waves (light, radio, microwave, uv, so on) but terribly challenging to produce gravitational waves.
For this reason, we need huge "antennae"; in fact, huge laser interferometers. These also cost a lot of money. To get some idea of the challenge, these interferometers are looking for changes in length which are smaller than atomic radii between two ends of the laser interferometer which are separated by about five miles. The smallest vibration in the mirrors can completely spoil all hope.
Why do we care? Well, we would like to see black holes, for starters. By definition, black holes are not visible, but by detecting the gravitational waves they produce, we will be able to pinpoint their location, masses, spins, speed, and that is all it takes to describe a black hole. Moreover, we will be able to learn about the structure of neutron stars and matter at extremely high density.
In the meanwhile, we produce pretty movies and hope.
