Michio Kaku: Escape to a Parallel Universe | Big Think

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Dr. Michio Kaku is the co-founder of string field theory, and is one of the most widely recognized scientists in the world today. He has written 4 New York Times Best Sellers, is the science correspondent for CBS This Morning and has hosted numerous science specials for BBC-TV, the Discovery/Science Channel. His radio show broadcasts to 100 radio stations every week. Dr. Kaku holds the Henry Semat Chair and Professorship in theoretical physics at the City College of New York (CUNY), where he has taught for over 25 years. He has also been a visiting professor at the Institute for Advanced Study as well as New York University (NYU).

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Card: How might the universe end?

Michio Kaku: Well, when we try to look at the whole universe itself -- many people ask the question, "Well Professor, how do you know -- how do you know that the universe is expanding? How do you know that it came from a big bang? How can you project so far into the future, billions to trillions of years into the future? Well one way we do this is by looking at the Doppler shift. Now, the doppler shift is something that even children are familiar with. When children play "Star Wars" with each other, they go err, err, err with their rocket ships. Right? Well, what makes that err, sound? It's the Doppler effect. When a car moves toward you, the pitch is higher, when the car moves away from you the pitch is lower. And it sounds like this. Eee err. We've all heard it. Same thing with starlight. When yellow light moves toward you, it turns greenish and bluish. When the yellow light moves away from you it turns reddish.

Now, how can you memorize this? Well, I was reading a paper a few years ago and I read this fascinating story of a high school physics teacher who got a speeding ticket for running a red light. The physics teacher went to the blackboard and said, "Your Honor. My car was moving toward a yellow light. Light is compressed in a forward direction when you move toward it, and therefore it turned green. This is the Doppler shift," he said. And he went to the black board and he correctly wrote down all the equations of the Doppler shift. And then this high school physics teacher said, "Your Honor. I do not deserve a traffic ticket." Well, the judge scratched his head and according to the article, the judge said, "Well, I guess there is a law higher than the state of New Jersey, and these are the laws of physics." But then, according to the article, there was a high school kid in the court room and he raised his hand and he said, "Your Honor, I'm just a high school kid, but I happen to be in his high school physics class and he just taught this a couple of weeks ago that this only happens when you approach the speed of light." End of article.

To this day, I still don't know what happened to that poor high school kid. But I tell my students, that if I'm ever in court arguing a speeding ticket or red light, they better not raise their hand if they know what's good for them and they know what's good for their grade.

So, when we look in the heavens, we look at starlight emitted from distant galaxies and we find that the light is slightly reddish. Redder than it's supposed to be. That means that these objects, the gigantic galaxies are moving away from us and therefore the universe is expanding. Well, we could run the video tape backwards, and by running the video tape backwards we could then calculate when all these galaxies came from a single point. And that's how we calculate the age of the universe, by simply hitting the rewind button when we calculate the expansion of the universe.

So by running the video tape backwards, we see that the universe is about 13.7 billion years old, plus or minus 1%. So, we now know the age of the universe. 13.7 billion years by running the video tape backwards. But what happens if we hit fast forward. What happens if we go forward in time billions of years? Well, here it gets murkier. But by analyzing how the universe has been expanding in the past, we used to think that the universe is slowing down. We used to think the universe is aging and therefore it's slowing down; running out of steam. Wrong. We now believe that the universe is speeding up. It's actually accelerating, in runaway mode which means that in stead of dying in a big crunch, we'll probably die in a big freeze.

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