Are We Alone?
Not Extraterrestrials, other Universe!
Horizon - How BIG is the Universe?
Anthony Aguirre
There may be one final, bizarre twist on the road. Because Anthony Aguirre thinks our universe may not be alone.
Anthony Aguirre "Sometimes when I'm headed down the highway and I'm driving, you know, my wife will say, Anthony, you're going 40 on the highway.
And then she knows that I'm thinking about other universes."
He thinks there may be other universes because of the process that created our own. It's called inflation. It describes an exponential expansion
in the moments after the Big Bang, at a speed the universe would never repeat again.
Inflation may have started out as a mathematical theory… But it has gained acceptance after successful testing against the evidence from
the cosmic microwave background.
Anthony Aguirre "I was amazed when I saw the results, come in from those satellites that reproduced all the bumps and wiggles and all the detailed
properties of that microwave background that inflation had predicted."
Inflation explains how the observable universe developed.
Soap Bubbles
Anthony Aguirre "It was doubling in size over and over again in a tiny fraction of a second, going from something like a billionth the size of
a proton to something may be the size of a bubble, a soap bubble."
But inflation didn't stop with our own universe. Anthony believes it may have happened over and over again.
Anthony Aguirre "This is really a side-effect. It's a huge side-effect, it's an amazing side-effect, but it is a side-effect of
something we invented already for a different purpose."
It's a process called eternal inflation.
Anthony Aguirre "There could be as many as we can imagine."
Anthony's vision – of an infinite number of infinite universes – may sound far-fetched. But the search is on to find evidence to support it.
Evidence from the oldest part of our map.
Dr Sean Carroll
Anthony Aguirre "Every once in awhile we could have sort of a cosmic collision with another bubble leave an impact, it would leave a bruise,
a disc in the sky on the microwave background radiation that we could look for."
Anthony and his colleagues have simulated what a collision of universes would look like. A bruise, superimposed on the cosmic microwave
background. He doesn't yet have enough data to test it, but it's a tantalising glimpse of what the map could reveal with the next
generation of satellites.
Anthony Aguirre "In principle I think this scenario with all these bubbles is testable, we can actually go out and look for them."
This may be the ultimate map of the universe.
Anthony Aguirre "We're talking about understanding and testing and theorising in a scientific way about an infinite number of universes.
It simultaneously so mind-boggling and yet it's still rigourous science – do mathematics, they do experiments, we can really test it."
Sean Carroll "Someday we'll understand the universe so well that we can literally take that map, put it on a little compact disc and put it
in our pockets and take it home."
