"That is how the scientists say the universe is laid out."
Big Bang(s): Universe dies and is reborn endlessly: theory
Adam McDowell, National Post
Friday, Dec. 3, 2010
Ripples of radiation in the sky have all but convinced a famous British physicist that the Big Bang was not the true beginning, that the universe dies and is reborn endlessly, and that the laws of existence permit at least a glimpse behind the curtain of infinity.
Last month, Oxford University physicist Sir Roger Penrose and an Armenian colleague, Vahe Gurzadyan, published a paper online arguing that the cosmic microwave background radiation that surrounds us at all times contains circular patterns of relatively uniform temperature. Mr. Penrose believes these are echoes of collisions between supermassive black holes in what he calls the “aeon” before our own, a universe separated from ours by the Big Bang.
According to the theory, billions of years from now, practically nothing will be left in the old, cold and enormous universe.
Time itself will end, because it can only exist if there are particles with mass to experience it. If there is no time, distance cannot exist either. So when the last mass vanishes, a universe that was unimaginably huge will have no size at all, setting the stage for another Big Bang.
Until this fall, Mr. Penrose said this week, he expected he might never see potential evidence of anything older than the Big Bang.
“I’m saying not only was there something before, but what there was before was the remote future of a previous aeon,” he said. “If the idea isn’t shot down by something that we’ve missed, this gives us a handle on things we thought we’d have no idea about.”
The paper, with the somewhat impenetrable title “Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity,” contends that the 30 to 40 microwave radiation disturbances observed so far provide evidence of Mr. Penrose’s concept of Conformal Cyclic Cosmology (CCC). (The “WMAP” referred to in the title is a NASA satellite, the Wilkinson Microwave Anisotropy Probe.)
The paper has not appeared in a peer-reviewed journal, but the researchers have submitted it to the prestigious journal Science.
This is not the first picture of the universe to imply an infinite string of Big Bangs — earlier such theories were articulated in 1920s by the Russian cosmologist Alexander Friedmann, and in the 1930s by the American Richard Tolman — but its basic outline may be the most difficult to understand.
Previous theories involving cyclical universes have imagined one aeon giving away to another through “Big Crunches,” a contraction of the universe causing everything left to collide into a nothingness, but CCC is more esoteric than that.
“People always think I’m saying the universe comes back into a Big Crunch and then gets started off again, but that doesn’t work,” Mr. Penrose said.
Our universe, in his view, ends in something more like a Big Not Much.
Perhaps 10 to the power of 100 years from now — a time so far away that our 13.7-billion-year-old universe would appear to be an infinitesimal fraction of a second old to that future universe’s year — practically nothing will be left in the cold, diffuse and enormous universe except black holes, which will be radiating away into nothingness excruciatingly slowly.
Eventually even the black holes will “pop” into oblivion with roughly the force of an artillery shell, a comically tiny whimper on the cosmological scale.
“It just struck me that this was a particularly gloomy fate for this very wonderful universe of ours,” Mr. Penrose said over the phone from his home in England.
His CCC concept — some fellow cosmologists say it cannot even be dignified as a “theory” because it lacks the necessary mathematical underpinning — involves accepting the idea that when all of the universe’s mass eventually and inevitably has been sucked into black holes and transformed into energy, time and space will cease to exist as well.
Time only exists if there are particles with mass to experience it. If there are no longer any particles with mass left in the universe, nothing exists to keep time itself, the universe’s clock, ticking.
If there is no time, Mr. Penrose explained, distance does not exist either. Physicists regard time and space as being so intertwined that you cannot have one without the other. And because space is another way of saying distance, a timeless and spaceless universe is a distanceless one as well. “There’s nothing around to tell you how big you are,” he said.
In short, when the last mass vanishes, a universe that was unimaginably enormous suddenly has no size at all. The universe grinds to a dark and immeasurable halt. “You need to have some technical mathematics to make the whole scheme fit together — you have to look at the details. The leap of imagination here is … if there’s nothing around there to measure the scale of things, big and small are really equivalent,” Mr. Penrose said.
The hope for this dead universe lies in the fact that it begins to sound like the zero volume, infinite energy state that existed at the moment “before” the Big Bang. Mr. Penrose’s self-described “outrageous” claim imagines one universe’s corpse as another’s embryo.
“Now the thing to get your mind around, of course, is how can this little tiny squashed-up space at the Big Bang, enormously hot and enormously dense, be matched with the completely opposite state … enormously cold and enormously spread out?”
How indeed, question other physicists, cleaving to the old maxim that extraordinary claims require extraordinary evidence — which they have not seen yet.
Bill Unruh of the University of British Columbia has listened to Mr. Penrose’s talks, and understands the CCC concept to mean that the universe eventually “forgets all scales [that is, distances], and all scales, instead of being immensely large become immensely small, and a Big Bang starts again,” he wrote in an email this week.
“How that transformation happens I do not believe he has any explanation for — it is just ‘magic.’ ”
Prof. Unruh’s UBC colleague Douglas Scott is likewise unconvinced by the arguments in the latest paper and he also doubted the evidence for radiation speaking to us from a previous aeon.
“If this was true … it would be truly astonishing, and one of the most significant results ever discovered about the cosmos. Unfortunately, there are several problems with the claim,” he said in an email.
And he has difficulties with the way Mr. Penrose and Mr. Gurzadyan interpreted the WMAP data.
“The bottom line is that the result would be astonishing if it showed that there was structure before the Big Bang imprinted on the sky,” he wrote. “But as a scientist I am usually skeptical of radical claims. And I am very skeptical of this result!”
David Spergel, a Princeton University cosmologist who has helped Mr. Penrose examine the cosmic microwave background radiation for a whisper of old aeons, complained to Science News magazine that while the ripples would seem to be in step with the CCC concept, the paper lacks enough technical detail to evaluate the claims about them.
Mr. Penrose has argued that the data has been cross-referenced with information from BOOMERanG98, another microwave radiation probe.
His search for ripples in the cosmic microwave background radiation began with a brainstorm about what elements of a previous aeon could possibly intrude into ours.
He hypothesized that radiation from the collision of supermassive black holes in the last aeon would still be around to “kick” and disturb the canopy of microwave radiation created in the opening second of our aeon.
“What I imagined was something like rain falling on a pond, and each drop of rain causes this ripple going out,” he said.
Because black holes are likely, in an old universe, to pile up in multiple collisions that unfold over long stretches of time, Mr. Penrose expected to see sets of rings in the radiation glow centred around the sites of multple crashes. So in September, he asked Mr. Gurzadyan, who was combing the WMAP data for areas of unusually uniform temperature, if he saw concentric patterns of rings.
“He looked at me and said, ‘That’s exactly what you see,’ ” Mr. Penrose said.
Mr. Gurzadyan believed he could see them in a dozen places in the sky. Where there was one ring there was always at least one more, and sometimes as many as five altogether.
As elated as this left Mr. Penrose, it will take much more persuasion and evidence before other cosmologists will see the same thing (assuming they ever do), and he knows it. Once an advocate of the now-discredited Steady State theory of the universe, the 79-year-old is aware that cosmological models themselves are born, live and die in an apparently endless succession.
He said that over the last few years, his colleagues have listened, albeit skeptically. “I don’t think they were taking it too seriously, but people have tended to be pretty polite. They haven’t told me they thought it was completely daft, but I don’t think that meant they believed me.
“This is the way I’d tend to present it before: ‘Here’s a crazy idea, but maybe we should take crazy ideas seriously.’ And it is a crazy idea, if you like. I wouldn’t have presented it as something that was probably true. But I always thought it had a good chance of being true. Fifty-fifty. OK, a 30% chance,” he said.
“It’s grown way into the nineties now. The high nineties.”
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