An artist's impression of the Big Bang.
It's that time again for science to take centre stage. This year, National Science Week will host several events dedicated to exploring the sometimes tenuous relationship between science and religion.
The standout among these is the appearance of Lawrence Krauss, director of the Origins Project at Arizona State University in the US, who will speak on Friday at Melbourne Town Hall on the vexing question of why there is something rather than nothing.
Among other things, he plans to review key developments in cosmology and particle physics over the past 20 years that have revolutionised our picture of the origin and ultimate destiny of the universe.
Theoretical physicist Lawrence Krauss at CSIRO Discovery Centre.
Nature produces surprises greater than anything humans could imagine, Professor Krauss says. Over the past two decades, big discoveries in cosmology, particle theory and gravitation research have changed our world view – with far-reaching implications for understanding the universe's origins.
"The results of the past century have taught us that empty space is, in fact, far from the inviolate nothingness that we presupposed before we learnt more about how nature works," he writes in his book A Universe from Nothing (Simon & Schuster).
In particular, research showing that the universe is expanding at an accelerating rate has revealed that most cosmic energy resides in some mysterious form permeating empty space. The discovery, Professor Krauss says, has changed the nature of modern cosmology.
"For one thing, it has produced new support for the idea that our universe arose from precisely nothing," he claims. "It has also provoked us to rethink a host of assumptions about the processes that might govern its evolution and, ultimately, the question of whether the laws of nature are truly fundamental."
So exactly how might everything arise from nothing? "The amazing thing is that we have realised it is possible for the total energy of the universe to be zero," Professor Krauss says. "This defies common sense. But, when you include gravity, it is possible to have negative energy, due to gravitational attraction, as well as positive energy – so the two can balance out."
In other words, we could have a universe brimming with billions of galaxies, each containing billions of stars, and still have zero total energy. "It means one could start from a universe with nothing in it and eventually end in our universe – without violating notions about energy conservation, and with no need for supernatural shenanigans," he says.
The laws of quantum mechanics, combined with Albert Einstein's theory of relativity, tell scientists that empty space is somehow unstable. This, Professor Krauss explains, suggests that by starting out with nothing inevitably leads to something – provided that one waits for long enough.
Even better, he adds, when gravity is added to quantum mechanics, it is possible to start out with no space and no time, and spontaneously create a universe of space and time – just by relying on the laws of quantum mechanics.
"The characteristics we observe in our universe – involving some of the most earth-shattering discoveries in science – are precisely those we'd expect from a universe that came from nothing via quantum mechanics."
Does this demonstrate beyond all reasonable doubt that the universe sprang from nothing? "No," Professor Krauss admits, "but it makes it plausible – and that is worth celebrating."
Professor Krauss' ideas are controversial and not applauded by everyone. "I think Professor Krauss can't do without mathematics and mathematical laws," says Melbourne University philosopher of science Stephen Ames, who is a canon of St Paul's Cathedral.
"Professor Krauss would like to think that these do not contradict his sense of 'nothing'," Dr Ames says. "However, they do have effect – matter and energy 'pop' into existence including a closed universe with the total energy exactly zero."
Dr Ames believes the mathematics and the laws are in the mind of a deity. "If these laws include anything like quantum mechanics – a richer form appropriate to the multiverse – then could the multiverse could 'pop' out of 'nothing'?"
Professor Krauss, he adds, allows that if a deity were the cause of all causes, there would be no question about what created it. "The problem Krauss identifies is that he finds no evidence for belief in such a deity. That opens up another discussion."
Graham Dorrington, who studied applied mathematics and theoretical physics at Britain's Cambridge University and is currently at RMIT University, says there is no quick and convenient route to a understand the principles of cosmology.
"It requires considerable effort to fully understand, like many other topics such as the compositions of Stravinsky, or the intricacies of clockwork mechanisms, or indeed how to make a good spinach souffle with anchovy sauce," Dr Dorrington says.
"The essential language of cosmology is mathematics, not commonplace words which are open to misinterpretation," he points out. "For example, when Professor Krauss uses the word 'nothing', he is actually referring to the observed vacuum of space between galaxies that is now thought to contain virtual particle pairs, and therefore to have a non-zero vacuum energy."
Furthermore, Dr Dorrington reminds, all regions of observable space must contain some radiation.
The stark realisation that nothing might well be crucial to the evolution of everything came with the recognition that empty space, devoid of all particles and radiation, actually weighs something.
By putting energy in empty space, it becomes gravitationally repulsive, unlike other forms of matter and energy that are gravitationally attractive.
This was proposed at various times by several physicists, Professor Krauss included. Most importantly it was confirmed observationally by two teams that demonstrated the universe's headlong expansion was speeding up. The implication was important: 70 per cent of the universe's energy resides in empty space.
As it turns out, this is exactly the amount of energy scientists were missing when they tried to understand how the universe's total gravitational energy could be zero. "Endowing empty space with energy may make it seem like something rather than nothing, but there really is nothing there – no particles, no radiation, no stuff at all," Professor Krauss says.
Having space may make it different from true nothingness in some people's minds. "This renders the possibility that space itself could suddenly pop into existence more interesting – because most people would agree that no particles and no space is a good approximation to nothing at all. One can even argue that the laws of physics themselves can spontaneously appear when the universe appears. No laws, no space and no stuff – that really sounds like nothing."
But is it really? Critics say the timeless non-space from which the universe is believed to have emerged is perhaps another, more fundamental form of nothingness. Who knows?
A strange theory
Something called M-theory might, in one fell swoop, provide support for Professor Krauss' notion that the universe arose from nothing.
"Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist," writes Cambridge physicist Stephen Hawking in his book The Grand Design (Bantam Press), co-authored with physicist Leonard Mlodinow. "If it [the universe] is finite – and this has yet to be proved – it will be a model of a universe that creates itself. We must be part of this universe, because there is no other consistent model."
In a nutshell, M-theory is a fundamental model of physics invoking no less than 11 dimensions. It's an extension of string theory in which particles, usually conceived of as tiny blobs of frozen energy, or even points, are one-dimensional wiggling strings with length but no breadth. The reason only some of the 11 dimensions are experienced, physicists say, is that the other dimensions are imperceptibly curled in on themselves.
By explaining how time existed as a dimension of space for a tiny fraction of a second after the big bang, scientists dispense with the question of what happened before the universe's birth, which apparently arose from a quantum fluctuation.
There is nothing unnatural about this, physicists say: such fluctuations go on all the time in the supposed vacuum of space. In this regard, they form an integral part of Mother Nature's sometimes hard-to-fathom make-up.
The big question is whether M-theory is testable. At the moment, most experts say no, including Oxford University physicist Roger Penrose.
But as experimental techniques improve, M-theory may one day prove to be testable, though exactly how requires a super-stretch of the imagination. After all, scientists have no access to other universes to discover what sorts of bizarre laws might govern them – or indeed, whether they actually exist.
Even if the universe were to be merely the remarkable out-working of a humble quantum fluctuation, at least one unsettling question remains: what was the origin of the laws that gave rise to the cosmic blip in the first place?
"The possibility that many separate universes exist, either separated in space or in extra dimensions, and in each of which the laws of physics might be different, has arisen naturally out of our understanding of particle physics and cosmology," Professor Krauss says. "It provides a landscape to understand not only how our universe, our space and time, could have arisen from nothing, but also how the laws of physics themselves could have arisen naturally, and randomly."
Overall, Professor Krauss requires a multiverse, with all of its possible universes having distinctive laws, in order to explain how our universe could "pop" into existence, supposedly from nothing, concludes Dr Ames.
"So is he really explaining how we get something from nothing?" he asks. "Isn't the multiverse just a 'brute fact'? Alternatively, could the multiverse 'landscape' also have 'popped' into existence, according to some still deeper law?"
Join an audience at St Paul's Cathedral from 10am to midday on August 14 when a panel of experts answers questions from schools: www.scienceweek.net.au/the-search-for-et-and-what-it-means-for-us/
Learn about other science week activities in Victoria at: www.scienceweek.net.au/events/?search-state=VIC&search-type=All+types&search-date-start=Today&search-date-end=All+dates&text=
Find out more about the machinations of M-theory at:
More on Lawrence Krauss at Melbourne Town Hall: http://lifeuniversenothing.org/event/16/view
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