>>Hi guys, i just want to know how exactly scientists observe gravitational waves?
Gravitational waves stretch and compress space/time; and, they're *very* small - on the order of the width of atom nuclei. There are two efforts (that I'm aware of) trying to detect them - LIGO, and GEO600. These are L-shaped detectors, shooting a laser beam down a long tunnel to a mirror, and looking for any interference within the beam; interference means that space/time is stretching a tiny bit - by gravitational waves. Each leg of LIGO is something like a kilometer long; there's a proposal to send up 3 spacecraft in solar orbit up to 500 km away from each other, but it's only a proposal at this point.
>>is they observe it using spectroscopy that showing to us the ripples of light of two or more galaxies that they assumpt inside there has massive blackhole and they would be collide and produce ripples effect of light of that galaxies?
Well, nothing so grandiose; They *are* looking for black holes (stellar-size) colliding - as prior to their 'colliding' they would spiral around each other, faster and faster, creating a great source of gravitational waves; There *was* an explosion of sorts detected back in the 70's, very far away, that *might* have been the collision of two black holes, but neither LIGO or GEO600 had been built when that occurred.
>>if yes, what about if that ripples effect or distortion of light of that galaxies actually caused by lens distortion effect from massive fluids that orbiting or rotating in space due to gravity, just like what i suggest before in my previous question, but they are still liquid in near absolute zero temperature?
Liquid or not, it's the motion of *mass* that causes the gravitational waves. And there would be no 'distortion of light', as the waves we detect aren't in the wavelength of light.
>>what about there's an element that we don't know yet made by mixture of hydrogen abd another compounds that produce transparent liquid elements just like waters that didn't frozen in near absolute zero temperature?
Again, regardless of the material, it's the motion of *mass* that causes the waves; and, the more compact the mass, the more intense the waves will be; a cloud of hydrogen won't move as a single entity, whereas a black hole or a neutron star will.
>>we know that hydrogen is a primary elements of our universe, and we know our waters made by hydrogen and oxygen. what about if there's a massive fluids made by hydrogen just like stars reacted as nuclear fusion that become plasma, but instead become plasma, their chemical reaction become massive transparent fluids, and become what scientist today call it dark matter?
I'm going to say that hydrogen - the lightest element there is - doesn't have the properties needed to be included in the realm of Dark Matter; regardless of what it's combined with, and - as far as we know, it will only combine with other atoms - it's size and density would mean that it's clearly not part of being Dark Matter.
>>i think it's possible guys, what do you think?
I don't think so...