Dark energy and quasars - they're mysterious forces behind the creation of the universe that few of us understand. But scientists now claim they have discovered that the speed at which the universe expands varies with time - and it's now accelerating rapidly. Dr. Mat Pieri from Portsmouth University is the co-author of the study - we asked him how it was possible to measure the speed of the universe's growth.
I think it useful to start with what’s happening with the universe in the present days. The universe appears to be accelerating in its expansion in that’s mysterious substance we “call dark” energy, which is really just a name of something we don’t understand, honestly. So if we go back to the first step of the history of the universe, that expansion was actually decelerating and that deceleration was caused by the gravitational pull of the objects in the universe of that time. When you say the universe is expanding and doing it more quickly, presumably, these’re forces and magnitudes of size that’s very difficult for the human brain to understand. Yeah. It’s an odd scale in general. It’s very difficult to wrap your head around the kind of physical scales that we’re probing. We’re looking at the universe 11 billion years ago. The universe was a different place then, it’s very difficult to picture what it was like and what kinds of scales are being discussed. We’re really looking at structures in the universe on truly mindboggling scales. Typically, we think that the scale of the galaxy is pretty mindboggling. But then you have to a whole of the scale where a galaxy is like a point and you just have enormous distribution of these points. It’s really mindboggling scales. And you’re talking about a period – 11 billion years ago, a scale that really doesn’t mean much for most people, because it’s so huge. In the essence, I believe, your research measures the distribution of gas in different areas of what we call the universe. That’s right. And I think that’s quite a unique technique. We’re looking at background objects, it’s not really important what they are in the purposes of this brief discussion, but these are very bright distance sources of light in the early universe. And what we do is effectively we see what happens to light when it leaves one of them and its voyage all the way to Earth. So, in principle, at least that whole voyage could be displayed out on the properties of that light. And do we know what these gases are? Yeah. I’d say we do. There’ve been various studies in the past about this gas which we know as “intergalactic medium”. We know quite a lot about it. And what we haven’t really done is mapped out on a kind of scale that we’re doing today. This intergalactic medium is mostly pretty remote stuff, but there’s really no part of the universe that is really empty of matter. There’s always something. And that’s what we’re looking at. Does it help us understand how it all came into being, in the first place? That’s a big question. I think it’s really baby-steps towards that question. What we’d like to know first is what this strange matter the universe is made of is. And then maybe after we understand what dark energy is, maybe we can say a little bit more about the way the universe came to being. I think it’s slightly a different question in the sense that there’s genuine debate whether it’s even possible to know what started the universe, what caused the big bang. So I think we have to satisfy ourselves with the question of understanding what the universe is before how it came to be. Source: Voice of Russia
