An Interview (of sorts) With Dr. Michio Kaku Part I


Michio Kaku (born January 24, 1947) is an American theoretical physicist, futurist, and popularizer of science (science communicator). He is a professor of theoretical physics in the City College of New York and CUNY Graduate Center. Kaku has written several books about physics and related topics, has made frequent appearances on radio, television, and film, and writes online blogs and articles. He has written four New York Times best sellers: Physics of the Impossible(2008), Physics of the Future (2011), The Future of the Mind (2014). Kaku has hosted several TV specials for the BBC, the Discovery Channel, the History Channel, and the Science Channel.

If you don’t follow his Twitter feed you really should. He has been posing scientific riddles the past few months and then answering them a week later. If you’re like me you can’t wait a week to find out the answer. Here are some of his most interesting answers:

If time travel is possible, then how can you become your own mother, father, son, and daughter, all at once?

1. an orphan (Jane) has a sex change operation and turn into Jim

2. Jim goes back in time, meets Jane, and has a baby

3. They go back in time and drop the baby at an orphanage, who then becomes Jane.

If time travel is possible, then physics allows you to become your own mother, father, son, daughter. You are your own family tree. But the normal laws of genetics forbids this. Question: why?

If time travel is possible, then genetically can you be your own mother, father, son, and daughter? No. Females typically have XX chromosomes, while males have XY. A time traveler would have to change their sex chromosomes, which today is impossible.

Two twins are in two separate but identical rockets, on a collision course. Their telescopes tell them that the other twin in aging slower than normal (as predicted by Einstein). This means you have two twins, each younger than the other!! How is that possible??

If two twins are rocketing towards each other in a collision course, and each has a telescope and sees the other twin aging slower, then how can two people each be younger than the other when they meet?  When the twins meet, they come to a halt, and each sees the other aging rapidly, as light catches up to them, until they both have the same age. “Younger” and “shorter” has no meaning in relativity unless you bring the twins together in the SAME frame.

Time travel is full of paradoxes e.g. going back in time and killing yourself as a child. (How can you exist if you just committed suicide in past?) But the quantum theory gives us the simplest solution to these paradoxes, in just one sentence. What is that sentence?

In the Many Worlds theory, the time line splits or forks, hence you wind up in a parallel universe when you go back in time, with NO paradoxes at all.

If we take Einstein’s general theory of relativity, and then set the speed of light to be infinite, then what happens to the equations of Einstein??

The answer is: Einstein’s equations reduce to Newton’s laws. So in a Newtonian universe, all messages are sent infinitely fast (which is incorrect.)

With a quick glance at Newton’s equations, how can you tell immediately that it violates relativity? With a quick glance at Einstein’s equations, how can you tell that it violates the quantum theory??

The answer is: Einstein’s equations reduce to Newton’s laws. So in a Newtonian universe, all messages are sent infinitely fast (which is incorrect.)

What happens if you have dark matter in your hand and let go?

Dark matter will penetrate your hand and fall through the floor, through the center of the earth, reach the other side of the earth. It will then oscillate back and forth through the earth, forever.

In the final scenes of the movie Interstellar, what was Matthew McConaughey doing, floating in some kind of prison? What scientific principle was being explored?

With just a glance, how do you tell that Newton’s laws violate relativity, and relativity violates the quantum theory? Newton’s equation do not mention c, light speed, and Einstein’s theory makes no mention of h, Planck’s constant.

What might alien intelligent life look like?

I don’t know. But own evolution favored 3 things: a) some form of stereo eyesight b) some form of thumb or grasping instrument c) language. Even on earth, among animals only humans have developed all three.

How to verify string theory?

Critics claim that string theory is untestable. But there are number of experiments to test it. If dark matter particles are create by the LHS, or found in detectors, they might be photinos, the super particle of the photon predicted by string theory.

What was Matthew McConaughey doing, floating in a cell at the end of Interstellar?

He was floating in the hyperspace predicted by string theory. Since 10 and 11 dimensions cannot be described on film, the producers had him floating in a 4D hypercube.

Can you prove the existence of God?

Probably not. Science is based on evidence which is testable, reproducible, and falsifiable. So God is outside the usual boundary of science. Also, it is impossible to disprove a negative, so you cannot disprove the existence of God, either.  Similarly, you cannot definitively prove the non-existence of unicorns. So I am not an atheist. I personally find much wisdom in Einstein’s belief in the God of Spinoza, a God of beauty, simplicity, elegance, and truth, when the universe might have been random, ugly, and chaotic.

My colleague, the late Stephen Hawking, did not believe in God because  there was no time in which to create the universe right after the big bang.  But string theory actually takes you before the big bang, to the multiverse. So the big bang is the not the beginning of time.  String theory leaves open the possibility that our bubble/universe collided or fissioned into other universes, as in a bubble bath, so there was a multiverse of universes before our universe was born. This idea might even be testable.  So the big bang was just the collision of two universes, or the fissioning of a universe into a baby universe. This concept fits into the inflationary universe theory, which all the data and is the leading theory of the big bang itself. So time did not begin with the big bang.

If the universe is expanding, then what is it expanding into?

Personally, I believe the universe is expanding into hyperspace, ie. into 11 dimension, according to string theory, like a floating bubble in a much larger arena.  However, the standard answer is that it’s just the distance between galaxies that is increasing, so the universe isn’t expanding into anything at all (like uniformly stretching a two dimensional sheet of rubber, which only expands in the same two dimensions, not three).

If nothing can escape the grip of a black hole, then why doesn’t it suck in everything, including the earth?

Far from the event horizon, the gravity around a black hole is Newtonian, i.e. diminishes like the inverse square of the distance. Hence, the earth orbits safely around the black hole at the center of the galaxy.  If an object gets too close to the event horizon of a black hole, then it might get sucked in. But farther away from the event horizon, the gravity field looks normal, so stars orbit safely around it.

Mars once had great rivers, lakes, perhaps even oceans. But they all disappeared billions of years ago. Why?

The leading theory is that Mars has a very weak magnetic field, so cannot protect itself from the harsh solar wind, which gradually dissipated the atmosphere of Mars. This caused the oceans to boil and evaporate into space.

The electromagnetic spectrum is huge, ranging from radio, TV to X rays and gamma rays, yet our eyes can only see the tiniest sliver of this huge spectrum, visible light. Why?

In general, the size of an antenna is roughly the size of the wavelength. Our antennas are the cells in our retina, which are roughly the size of the wavelength of light, not radio or gamma rays.  So if the cells of our eyes were many feet across, we could see radio. In other words, our eyes would look like a radio antenna. So we can only see EM waves the size of our cells, e.g. visible light… so if our cells and receptors were the size of a radio telescope, perhaps we could see the afterglow of the Big Bang itself filling up the sky.

The brain is not a digital computer. It has no operating system, no Windows, no CPU, no Pentium chip, no programming, no algorithms, no subroutines. When what is it?

It is a sophisticated learning machine, a very advanced neural  network. After a making a mistake, the wiring of the brain actually changes to get closer to the answer.

Where does Einstein’s theory of gravity completely break down? (Einstein himself knew this, that is he was searching for the theory of everything, the unified field theory.)

At the center of a black hole, and the instant of the Big Bang. If r is the effective size of a singularity, then gravity behaves like 1/r, which is 1/0, which is nonsense.  Einstein himself knew this, and that is why he was searching for a unified field theory. Also, that’s why he invented wormholes in 1935, to try to eliminate the 1/r problem (since wormholes are not singular). But so far, only string theory can eliminate these 1/r problems.

A star’s gravity can effortlessly squeeze hydrogen until it ignites. But fusion with magnetic fields on the earth is notoriously difficult. Why is that? What is the fundamental difference between gravity and magnetism??

Magnetism is based on dipoles (north and south poles) while gravity is based on monopoles of matter. Hence, stars can easily spherically contract under gravity, causing them to ignite. But dipoles are difficult.  To use magnetism to squeeze hydrogen, you need to shape the magnets like a doughnut, with the gas inside. Doughnuts are much more difficult to squeeze than spheres. Hence we don’t have fusion reactors on the earth today.



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