Universe will end sooner than thought

News.com.au-- THE end of the universe is not nigh, but it could be closer than originally thought.

Australian scientists have measured the amount of the universe's stored energy that has been lost - in a process known as entropy - since the Big Bang.

The result, as calculated by Dr Charley Lineweaver and PhD student Chas Egan, was about thirty times higher than other projections indicating there was less left in the universe's "gas tank".

"It's a bit like looking at your gas gauge and saying `I thought I had half a gas tank, but I only have a quarter of a tank," said Dr Lineweaver, from the Research School of Astronomy and Astrophysics at Australian National University (ANU).

"But I can't tell you how many kilometres you can go on that quarter of a tank yet."

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Dr Lineweaver said work was under way to use the higher entropy figures to produce new estimations of how long the universe would continue to be capable of supporting life.

One complication, he said, was the lack of scientific consensus on the "maximum entropy state of the universe" - how much energy was available and therefore how much could be lost.

Dr Lineweaver said this issue aside, the universe appeared to be headed towards a state of "heat death" when all of its stars, planets and other matter would reach exactly the same temperature.

"It's kind of like your coffee cup cooling down ... when your coffee cup reaches the temperature of the room it is in, that's equilibrium," he said.

"The stars, which are burning hydrogen, are like the coffee cup - they're hot and slowly cooling down.

"The question is, when will it end? ... And all you can say is we are closer to the heat death than we anticipated."

While it all sounds a bit doom and gloom, Dr Lineweaver said this process was unfolding over an immensely long period of time, and humans would face a momentous event within our own solar system well before any ultimate unravelling of the universe.

The sun was expected to swell up to form a "red giant", making the earth uninhabitable, in about five billion years before making the transition to a cooling white dwarf star.

"There is no doubt in any astrophysicist's mind that the sun will run out of fuel and expand into a red giant in about five billion years," he said.

"If there is going to be a heat death, we're talking many, many times longer than the lifetime of the sun ... it's a much longer time scale."

The research paper, entitled A Larger Estimate of the Entropy of the Universe, has just been accepted for publication in the Astrophysical Journal.