Two Supermassive Black Holes About To Embrace 171
Taco Cowboy writes "NASA's WISE (Wide-field Infrared Survey Explorer) satellite was looking at a distant galaxy, some 3.8 billion light-years away, and saw something rather unusual. At first they thought that they saw a galaxy was forming new stars at a furious rate, but upon closer checking, they found that they were seeing two supermassive black holes spiraling closer and closer to each other. The dance of this black hole duo started out slowly, with the objects circling each other at a distance of about a few thousand light-years. As the black holes continued to spiral in toward each other, they were separated by just a few light-years. Supermassive black holes at the cores of galaxies typically shoot out pencil-straight jets, but in this case, the jet showed a zig-zag pattern. According to the scientists, a second massive black hole could, in essence, be pushing its weight around to change the shape of the other black hole's jet. Visible-light spectral data from the Gemini South telescope in Chile showed similar signs of abnormalities, thought to be the result of one black hole causing disk material surrounding the other black hole to clump. Together, these and other signs point to what is probably a fairly close-knit set of circling black holes, though the scientists can't say for sure how much distance separates them."
Did not read article yet, but... (Score:2, Interesting)
So.. if they observed these black holes at a few thousand light years apart, and then some time later (assuming less than a few thousand years later) at just a few light years apart... does this mean that they are moving toward each other at faster than the speed of light?
Gravitational Waves (Score:5, Interesting)
Given the countless galaxies, each with its own supermassive black hole, just like intersecting waves, the gravitational waves could theoretically act like waves in the electromagnetic spectrum, or classical physics experiments with waves. Some waves would cancel, others would be much larger than the 2 source standing waves, and thus would appear as a stronger signal to a gravitational wave detector, given said detector was sensitive enough.
Gravitational waves could also bring us closer to the point in time of the "big bang" than the cosmic microwave background radiation images. I sincerely hope this discovery, gives solid reason to develop said gravitational wave detector. Kudo's to the NASA WISE team!
Re:FSVO "about" (Score:5, Interesting)
Did it really? I think that's a philosophical question. Personally, I think not only space and time but also cause and effect are relative to the spectator.
The light carrying the information that this is happening is just arriving here. The speed of light is also by definition the fastest information can travel. It may "in reality" have happened 3.8b years ago, but the effect can only now affect someone here. Even if you happened to have an observation post there and 3.8b years ago they noticed "hey, they're falling into each other NOW", and they sent that information right away, the information would not have reached us before the event since, well, the information of the event ITSELF is traveling at the speed of light, which, as stated before, is the fastest an information sent to us by the observation post could have traveled.
Long story short, the absolute moment in time when something happens does not matter as long as you cannot overcome its information propagation speed. It will of course change if someone happens to find a way to propagate information faster than the speed of light... which would open a completely different can of worms if you ask me (but that's beyond the scope of this post now).
What this all comes down to is that the absolute moment of some event does not matter, but only the relative moment that you receive the information.
Re:FSVO "about" (Score:3, Interesting)
Galaxies are travelling away from us faster than the speed of light from them can reach us. Aren't they traveling faster than light? Oh, that's expansion... So, if it's space that's moving then the matter doesn't have to travel through space to achieve faster than light speeds.
That's just the result of a weird (put pragmatically practical) definition of space-time coordinates called "co-moving coordinates".
According to the "normal" rules of special relativity, the speed of light relative to us is the same everywhere, there's no such thing as "space itself expanding", and nothing goes faster than light. However, using those same definitions, we are the oldest part of the universe (using our reference system), all distant galaxies moving away from us at high speed are aging more slowly, everything gets more distance-contracted further out, and at a distance equal to the speed of light times the age of the universe, the big bang is only just beginning and time is standing still. Not just because we have to wait for the light to get here, but "right now", correcting for the travel time of light. It's just a result of relativistic time and distance contractions. Other civilisations out there will use themselves as the reference point and will have a similar view centered around them. In fact, we may say that they don't exist yet while they say we don't exist yet and both are correct from their point of view.
However, since that's not a very practical and certainly not an objective model (no matter how correct it is), cosmologists decided to use a different coordinate system. A meter anywhere in the universe is defined as what's measured by a one meter stick that is moving together with the rest of the expanding universe (undoing distance contraction), and time is defined to be the time indicated by local clocks that are also traveling together with the expanding universe (undoing time contraction). The effect is that with this coordinate system, the universe is nicely homogenous, the same age everywhere, truly infinite, and there's no longer anything special about our location.
The downside is that the speed of light is now relative to the local "expanding space", and this space can exand more quickly than the speed of light. There's nothing physical about this "space", it's just a mathematical artefact resulting from the coordinate system we chose.
Very distant objects that exist "now" in the second model, will never be visible to us because their light is trying to get to us on a kind of cosmic conveyor belt moving the other way more rapidly. In the first model, those objects don't exist yet and never will because local time has slowed down to an asymptotic halt. The definition of "now" is just "the collection of events that we happen to have assigned the same time coordinate to", and this depends entirely on the choice of coordinates. There's no such thing as an objective "now". But no matter what coordinates you use, we all agree that we will never see those objects.
Both point of view are "correct", we are just measuring things a bit differently but all conclusions are the same. And no matter what model you use, nothing can ever overtake an actual photon in vacuum. Something at a distance may move faster than a photon here, but that just depends on how we define "time", "distance" and "speed". Nothing actually goes faster than a ray of light at the same location.