Before the beginning

Photo: NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)

This image of Abell 2744 is the first to come from Hubble's Frontier Fields observing programme, which is using the magnifying power of enormous galaxy clusters to peer deep into the distant Universe.

Current thinking is that the universe started just under 14 billion years ago. 

At that moment everything we see around us in the universe now, including space and time, was all scrunched into something about the size of an atom. Its density and temperature were so high our current physical knowledge cannot be applied to it. 

Then it started to expand, in an event now known as the Big Bang. As the embryo universe expanded, it cooled and became less dense, so that eventually hydrogen gas could form. This provided the raw material for making stars. The stars, in turn, made most of the other elements as waste products from their energy production. The rest were formed in the supernova explosions with which these early stars ended their lives. After a few generations of stars, the universe contained everything needed to make planets, and us. 

Having a specific start time for the universe raises some difficult questions. What was there before the Big Bang? How do we get a lot of something out of nothing? There must have been something, and where did all that something come from?

Things, including us, are made out of matter. This comes in two forms. There is "ordinary matter," which is what we, our planet, and as far as we know, most of the observable universe are made of. 

The other kind is "antimatter." This is a mirror image to ordinary matter. We know it exists; we have managed to make it using high-energy particle accelerators. If we put ordinary matter and antimatter together, they annihilate each other, producing a flash of energy. This produces a nice picture of making a universe out of nothing; we separate the nothing into ordinary matter and antimatter. As long as we keep them apart we have something. 

It is rather like having no money and borrowing, say, $1,000. You have a thousand ordinary dollars in your pocket, but you also have a debt of a thousand dollars, or if you like, a thousand antidollars. If you bring the dollars and antidollars together, paying off the debt, you will have nothing, but if you keep them apart, you can do all sorts of financial manoeuvring with both the money and debt. That's what investors do all the time. 

If this is the case, our universe should contain equal amounts of matter and antimatter. However, the visible universe is almost entirely made of ordinary matter. We can "balance the budget" if "the universe" does not in fact comprise everything. 

One idea is that the Big Bang was a two-way event, generating an ordinary matter universe expanding in one direction through time and an antimatter universe expanding in the opposite direction. The cash went one way and the debt another, keeping them apart.

One attempt to explain what happened before the Big Bang is that the universe just expands and collapses, repeating this over and over again. We have no proof of this, and the expansion of the current universe does not seem to be slowing down before starting to collapse; it is instead going faster and faster. It looks as though it is going to expand indefinitely, dying finally when the stars run out of fuel and the elementary particles making up the matter in the universe decay. This seems to fit a new idea, proposed originally by science fiction writers but getting a lot of serious discussion today. It is the idea that there is a multidimensional cosmic foam, in which universes start, expand and dissipate, like bubbles. The foam itself would be eternal, unless it is part of something even bigger.

One interesting possibility with the cosmic foam idea is that some of the universe bubbles may be touching each other, just like what we see in a bubble bath. If our universe is touching another, the interface should look a bit flatter than the rest of our bubble.  Searches are under way.

• Venus still dominates the western sky after sunset. 
• Left to right, Mars, Saturn and Jupiter lie close together low in the southeast before dawn. 
• The moon will be full on the 7th.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.