An eon, also spelled aeon, is the longest division of geologic time, so it's a difficult concept for most of us to wrap our minds around.
Sir Roger Penrose, a distinguished physicist at Oxford University, defines it as a period between successive big bangs in the universe.
This in itself is a heretical concept because to many cosmologists, the big bang was the beginning of the universe followed by a rapid period of expansion.
This is referred to as "inflation" in its earliest stages.
That later changed to a more sedate expansion, which has only recently begun accelerating.
In a phone interview with the Georgia Straight, Penrose said he accepts there has been an accelerated expansion of the universe.
He also subscribes to the widespread view of "sedate expansion".
But he questions the premise of what happened before that.
"I say that inflation didn't take place," Penrose said. "The big bang wasn't the beginning, either."
Tonight at 7:30 p.m. in a free lecture at UBC's Hebb theatre, Penrose will offer a revolutionary interpretation of the origins and future of the universe. He'll be joined by Nobel laureate Sir Anthony J. Leggett, a physicist at the University of Illinois at Urbana-Champaign, who will discuss why time can't run backward.
Penrose's theory that the big bang wasn't the beginning raises an intriguing question: what existed beforehand?
He said that in the very early universe, the temperature was so high that "the masses of particles became completely irrelevant".
"It's as though the particles in the very early universe had no mass," he said.
From there, he talked about black holes to illustrate what's to come in what Penrose called "the remote future".
"Our galaxy has a huge black hole in its centre about four million times the mass of the sun," he said. "That's relatively small as things go. These will swallow material. They don't swallow everything, but they will sit around for a long time and...when the universe expands an awful lot, these black holes will gradually start radiating away and disappear."
The black holes "basically" emit photons, Penrose added, which don't have any mass.
"By far, the majority of the particles in the very remote future will be photons," he predicted.
In other words, there are massless particles at both ends—before the big bang and in the remote future.
The "crazy idea", as Penrose puts it, is that the universe becomes insensitive to size.
"Our remove future will behave like the big bang of the next eon," he said. "You think of it as very different because our future will be low density, very cold, practically nothing out there. The big bang is very high density, very hot, everything all squashed together. But if you consider the physics, they're basically equivalent."
That's because both are characterized by massless particles.
"So the claim I'm making is that the remote future becomes the big bang of the next eon," Penrose said. "And our big bang was the remote future of an eon before ours. The difficult idea to get one's mind around here is how, if you have things with no mass, that they can behave in a way which makes sense."
When asked about the time frame for the universe to reach the remote future, Penrose was a little vague.
"I'm saying the time frame is actually infinite in the future," he replied.
He quickly added that for a massless photon, an infinite period of time "isn't really that long".
"Eternity is no big deal to a photon, you see," Penrose quipped. "The photons don't even notice that infinite time has passed."
In the meantime, he predicted that the sun will probably eventually swallow the inner planets then contract down into a white dwarf and then a black dwarf.
The Andromeda galaxy has a black hole 50 times the size of the Milky Way's largest, so according to Penrose, they will each swallow one another, as well as numerous stars.
"I won't say necessarily that our sun will survive this," he said. "It most likely will survive it, but there will be many other such collisions. These play an important role in my scheme, actually."
Penrose said that he has arrived at his conclusions with the help of an Armenian colleague who has done much of the data analysis. They published a paper in the European Physical Journal Plus. In addition, Penrose outlined the idea in his 2010 book Cycles of Time: An Extraordinary New View of the Universe.
Penrose, a former colleague of Stephen Hawking, said nobody has come forward with any serious challenge to his view. Rather, he suggested that it's being ignored by many cosmologists, even though a Polish group of researchers has been making similar claims.
He said that new satellite data of the distribution cosmic microwave background has raised serious questions about the conventional view of the inflation of the universe in its earliest period.
And he admitted to being somewhat troubled that cosmologists are not taking note of this and discussing it.
"Maybe someone will comment after my lecture," Penrose said. "I would be perfectly accepting if somebody said, 'Look, this doesn't make sense because we can explain it this way or you've done this wrong.' It is very exasperating. It's hard to understand, really."