New evidence, if backed up, could turn physics world upside down, writes Dick Ahlstrom, Science Editor
RESEARCHERS IN the UK have stunned the physics world after finding evidence that the universe may not have a dark side after all. If backed up by further analysis it means that scientists will have to come up with a completely new theory for the structure of the cosmos.
Our current ideas about what the universe contains are grounded on there being two mysterious substances out there, dark energy and dark matter. We don’t know what they are and we can’t see them but if they aren’t there then we are in big trouble.
Without them we can’t readily explain how the universe works and why everything in it is flying apart at a faster and faster rate.
Prof Tom Shanks and graduate student Utane Sawangwit of the University of Durham have turned everything on its head however, presenting evidence this morning in the Monthly Noticesof the Royal Astronomical Society that there may be no dark energy and no dark matter either.
This is not good news for cosmologists who since the late 1990s have built their theories on the assumption that everything we see in the night sky, all the billions of galaxies and stars, make up just 4 per cent of the total universe.
The theory goes that the bulk of it, at least 74 per cent or so is made of dark energy and another 22 per cent is this invisible stuff called dark matter. We don’t know what either of these things are, which in a way is a bad showing given there is so much of it about.
We can see what they can do however. Researchers last year presented evidence that dark matter can affect the movement of galaxies, interfering with their gravity.
Dark energy is far more important however. We have no clue how it works but the theorists believe that this invisible energy is spreading the universe inexorably outwards, overcoming gravity and pushing everything apart at a faster and faster speed.
So we are in deep trouble for a workable theory if these things are suddenly unavailable and that is precisely what the scientists are saying. “If our results prove correct then it will become less likely that dark energy and exotic dark matter particles dominate the universe. So the evidence that the universe has a dark side will weaken,” says Prof Shanks.
The work is based on an analysis of data from a satellite called WMAP. This was put into orbit in 2001 to observe leftover heat caused by another fundamental cosmological theory, the Big Bang. All the evidence out there suggests that the universe was created by the Big Bang explosion and WMAP can see the left over heat from this event that happened about 13.5 billion years ago.
The Durham researchers also looked at data from the Sloan Digital Sky Survey and this too points to no dark side to our universe. “If our result is repeated in new surveys of galaxies in the southern hemisphere then this could mean real problems for the existence of dark energy,” said Mr Sawangwit.
“This is very interesting work,” stated University College Dublin physicist Prof Brian McBreen. “He (Shanks) is a very respected guy and wouldn’t put his name to rubbish. It will add interest and spice to an European Space Agency satellite called Planck.” he said. Planck will also measure leftover heat from the Big Bang.