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:
Everyone says that every snowflake is unique. But how do we know that? No one examines every snowflake with a microscope. So how do we prove that every snow flake is different?
As a snow flake falls, the growth of its crystal arms changes with varying temperature, pressure, moisture. Since the path of every snowflake is unique, so therefore every snowflake is also unique.
What is my favorite science fiction novel?
Hands down, it would be the Foundation Trilogy by Asimov. As a child, it forced me to think of where humanity might be 50,000 years into the future. (Elon Musk also read that book as a child, I found out.)
Why did I become a physicist?
When I was 8, the newspapers said that a great scientist had died, and they published a picture of his desk, with his greatest, unfinished work. I asked myself: what could be so hard, that this great physicist could not finish??? I went to the library, and found out that this man was called Albert Einstein. And that unfinished book was the Unified Field Theory, the theory of everything. I decided that I wanted to try to help finish that book, to find this fabled theory unifying all the forces of nature.
What is my favorite science fiction movie?
Besides Forbidden Planet, it would be the old Flash Gordon series. As a child, it opened my eyes to the possibility of alien life in the universe (another admirer is George Lucas, upon which he based Star Wars.)
In the animal kingdom, very, very few animals snore. We humans are an exception. What other familiar animal snores, and why?
Very few animals snore. Over millions of years, our snout, jaw, began to get smaller, compressing our nasal cavity, causing snoring. Breeding of dogs (which were once gray wolves) also compressed the face of bull dogs and other animals, hence they snore.
Where does the most aging take place in a car? By analogy, then where does the most aging take place in the human body? Why does the answer to this hold an important clue to finding immortality?
In a car, its mainly in the engine, where you have oxidation and moving parts. In the cell, it is the mitochondria, the engine of the cells. That is also where mutations are concentrated. Aging, in some sense, is the buildup of errors in our cells. Since these mutations are concentrated in certain areas, perhaps one day science my repair the damage in these areas, such as the mitochondria, and hence reverse the effects of aging.
This tweet is written in English, rather than German, partly because the Nazis failed to build an atomic bomb. They failed, in part, because they did not know the value of one number. What is that number?
In part, it is because they did not know critical mass (about 20 pounds), the amount of enriched uranium necessary to build an a-bomb. One reason they did not know this is because all the top physicists fled the Nazis
Some things can go faster than light, like when you sweep the night sky with a flash light. The image went across millions of light years. But why doesn’t this violate Einstein’s special relativity theory?
If you sweep the night sky with a flashlight, does image of the beam eventually go faster than light? Yes. But no material object or information went faster than light, so relativity is not violated. The image is immaterial and hence can go faster than light.
If two electrons are vibrating coherently in unison, and are separated, then jiggling one electron instantly communicates information, faster than light. This is entanglement. But why doesn’t this violate Einstein’s theory of relativity?
Yes, but no net quantum information (e.g. Morse code) can travel this way. So Einstein was only partly incorrect. So Einstein was only partially right. Material objects (atoms, photons) and net information (e.g. Morse code) cannot go faster than light. But immaterial things can break the light barrier (e.g. the expansion of the universe in the big bang). So Einstein still has the last laugh. So this means that quantum entanglement cannot be used as the “subspace communicator” in Star Trek, allowing the Enterprise to communicate with Star Fleet Command instantly across the galaxy. But that still leaves open the possibility of wormholes. Going through a wormhole, you may theoretically zap across the galaxy, but your speedometer on your rocket always says you are going slower than light speed. Hence, special relativity is not violated locally going through a wormhole.
Why do hurricanes spin counterclockwise in the northern hemisphere? If you pull the plug in the sink, does the water drain counterclockwise as well?
As hot air rises, the earth spins beneath it slightly, causing it to swirl counterclockwise. This is the Coriolis force. In your sink, the slightest disturbance can nullify this weak force.
If you swing around a long steel rod from one end, and if the rod is long enough, will the end of the rod eventually exceed the speed of light?
If you spin a very long steel rod around you, will the end eventually go faster than light? No. If you jerk the rod, a shock wave travels along the rod, causing the shape to deform. If you jerk the rod so that it spins around you, the rod turns into a spiral. Since the shock wave travels much less than the speed of light (the shock wave actually moves comparable to the speed of sound) the rod never comes close to the speed of light.
Why is the sky blue, and the sunset red? Why is the night sky black, and not white? What is the color of the sky on Mars?
When you look at the sky, you are looking away from the sun at scattered light, and blue light scatters the most. At sunset, you are looking directly at the sun, through much of the atmosphere, and red light scatters the least. If the universe is uniform and infinite, then the sky should be on fire, since there is a star at every point you look. But since you look into the past when looking at distant stars, you eventually reach a cut-off, the big bang. So the sky is black because there was a beginning! So the night sky is black because there was a Beginning, a genesis to the universe. (I think about this when I take a shower.) The first person to solve this puzzle (Olber’s Paradox) was, of all people, Edgar Allen Poe, an amateur astronomer.
What is the color of the Martian sky? Its is pink. That is because it is full of small particles of dust, which contains rust. So Mars is the rusty planet.
Black holes absorb everything that gets too close. That’s why they are black. But this violates the quantum principle. Why?
Black holes cannot really be black. The quantum principle says that perfect Blackness violates the Uncertainty Principle, since you cannot have an object which emits absolutely no radiation. Hence black holes must be gray (which was Hawking’s contribution).
Why are stars and planets all round? And why are asteroids shaped like a potato?
Gravity is attractive, and evenly symmetrically compresses gases into a sphere. (A sphere has the least gravitational potential energy.) But small asteroids have little gravity, and hence they are shaped like a potato.
Where do Newton’s laws break down, requiring Einstein’s relativity? Where does relativity break down, requiring quantum gravity?
Newton’s laws are fine, except near the speed of light, or near large gravitational fields. Relativity breaks down at the center of a black hole, or at the big bang. Relativity is useless at the Planck energy (a quadrillion times greater than the LHC.)
When Einstein was 16 years old, he asked himself a fateful question: what happens if you can race along side a light beam? He changed human history when he finally found the answer ten years later. What is the answer?
When Einstein was 16, he dreamed of running along side alight beam, thinking that the wave would be stationary. But as a kid, he knew that stationary waves were never seen, so he concluded you could never race a light beam. Something was very wrong. When Einstein was in college, he finally learned Maxwell’s equations for light, and found the answer: light always travels at the same velocity, no matter how you measure it.. From this, he then showed that light speed was the ultimate velocity, so you could never outrace light.
If you are in a rocket ship traveling just below the speed of light, and then you fire a gun and turn on a flashlight, how fast is the light traveling? How fast is the bullet traveling?
If you measure the speed of a light beam on the earth, or inside a rocket ship traveling near light speed, light travels at the SAME velocity. If someone fires a gun inside the rocket ship, from the earth the velocity of the bullet does NOT exceed light speed. Time slows down inside the rocket ship. So someone inside the rocket ship measures the bullet’s speed as normal, as if the rocket were at rest. So the bullet NEVER exceeds light speed, either measured from the earth or inside the rocket.
How do refrigerators and air conditioners get cold? (Hint: it’s the same principle behind how stars get hot, before fusion takes place).
When a gas is squeezed, the energy of compression turn into heat, as in a star. When gases expand, they get absorb energy, and get cold, and that is how refrigerators work.
Biggest atom smasher in the world?
The Large Hadron Collider, the biggest atom smasher on earth, is down for the next 2 years. Then it will be at full power. Hopefully, it will find the photino, predicted by string theory, which may make up the dark matter filling up the universe. There is also a lesson here. In the 1990s, US physicists wanted to build the Supercollider (much bigger than the LHC) outside Dallas, TX. But Congress canceled it, so the US lost the lead in high energy physics. Lesson: we physicists have to learn how to engage the public, or else the public won’t fund us. The history of the Supercollider is a sad one. First, Congress gives us a billion dollars to dig the hole for the Supercollider. Then Congress cancels it, and gives a second billion dollars to fill up the hole. 2 billion dollars to dig and fill up a hole! That’s the Congress!
In the laboratory, scientists can artificially induce the feeling of being “out of body,” and also the near-death sensation of seeing the “light at the end of the tunnel.” How is this done? (Hint: see my book, The Future of the Mind).
The “light at the end of a tunnel” can be duplicated by putting pilots in an ultracentrifuge. As blood drains from their head, the outer rim of their retina loses blood, so you only see the center of the retina, so you see a light at the end of the tunnel. The “light at the end of the tunnel,” caused by a drop in blood pressure, can also happen in an accident, so therefore people think they have died and seen heaven. “Out of body experiences” can also be duplicated by electrically stimulating certain regions of the brain. By stimulating the boundary between two areas of the brain, it gets confused. To make sense of these contradictory signals, the brain interprets this as being outside the body. This effect can simply be created by an electrical probe to the brain.See The Future of the Mind.