Chris Anderson – Owner of TED
On a typical day at school, endless hours are spent learning the answers to questions, but right now, we’ll do the opposite. We’re going to focus on questions where you can’t learn the answers because they’re unknown. I used to puzzle about a lot of things as a boy, for example: What would it feel like to be a dog? Do fish feel pain? How about insects? Was the Big Bang just an accident? And is there a God? And if so, how are we so sure that it’s a He and not a She?
Why do so many innocent people and animals suffer terrible things? Is there really a plan for my life? Is the future yet to be written, or is it already written and we just can’t see it? But then, do I have free will? I mean, who am I anyway? Am I just a biological machine? But then, why am I conscious? What is consciousness?
Will robots become conscious one day? I mean, I kind of assumed that some day I would be told the answers to all these questions. Someone must know, right? Guess what? No one knows.
Most of those questions puzzle me more now than ever. But diving into them is exciting because it takes you to the edge of knowledge, and you never know what you’ll find there.
So, two questions that no one on Earth knows the answer to.
[How many universes are there?]
Sometimes when I’m on a long plane flight, I gaze out at all those mountains and deserts and try to get my head around how vast our Earth is And then I remember that there’s an object we see every day that would literally fit one million Earths inside it: the Sun. It seems impossibly big. But in the great scheme of things, it’s a pinprick, one of about 400 billion stars in the Milky Way galaxy, which you can see on a clear night as a pale white mist stretched across the sky. And it gets worse.
There are maybe 100 billion galaxies detectable by our telescopes. So if each star was the size of a single grain of sand, just the Milky Way has enough stars to fill a 30-foot by 30-foot stretch of beach three feet deep with sand. And the entire Earth doesn’t have enough beaches to represent the stars in the overall universe. Such a beach would continue for literally hundreds of millions of miles.
Holy Stephen Hawking, that is a lot of stars. But he and other physicists now believe in a reality that is unimaginably bigger still. I mean, first of all, the 100 billion galaxies within range of our telescopes are probably a minuscule fraction of the total. Space itself is expanding at an accelerating pace. The vast majority of the galaxies are separating from us so fast that light from them may never reach us. Still, our physical reality here on Earth is intimately connected to those distant, invisible galaxies. We can think of them as part of our universe. They make up a single, giant edifice obeying the same physical laws and all made from the same types of atoms, electrons, protons, quarks, neutrinos, that make up you and me.
However, recent theories in physics, including one called string theory, are now telling us there could be countless other universes built on different types of particles, with different properties, obeying different laws. Most of these universes could never support life, and might flash in and out of existence in a nanosecond. But nonetheless, combined, they make up a vast multiverse of possible universes in up to 11 dimensions, featuring wonders beyond our wildest imagination.
The leading version of string theory predicts a multiverse made up of 10 to the 500 universes. That’s a one followed by 500 zeros, a number so vast that if every atom in our observable universe had its own universe, and all of the atoms in all those universes each had their own universe, and you repeated that for two more cycles, you’d still be at a tiny fraction of the total, namely, one trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillionth. But even that number is minuscule compared to another number: infinity.
Some physicists think the space-time continuum is literally infinite and that it contains an infinite number of so-called pocket universes with varying properties.
How’s your brain doing? Quantum theory adds a whole new wrinkle. I mean, the theory’s been proven true beyond all doubt, but interpreting it is baffling, and some physicists think you can only un-baffle it if you imagine that huge numbers of parallel universes are being spawned every moment, and many of these universes would actually be very like the world we’re in, would include multiple copies of you.
In one such universe, you’d graduate with honors and marry the person of your dreams, and in another, not so much. Well, there are still some scientists who would say, hogwash. The only meaningful answer to the question of how many universes there are is one. Only one universe. And a few philosophers and mystics might argue that even our own universe is an illusion.
So, as you can see, right now there is no agreement on this question, not even close. All we know is the answer is somewhere between zero and infinity. Well, I guess we know one other thing. This is a pretty cool time to be studying physics. We just might be undergoing the biggest paradigm shift in knowledge that humanity has ever seen.