Ask Michio Kaku

August 29th, 2007

Have a question you would love to ask Michio Kaku? Send it in to web@mkaku.org with your name and where you’re from.

When do you think we’ll first discover life beyond Earth? Will it be on Mars, our moon, Jupiter’s moon Europa, or somewhere else?
Sarah B.
Austin, Texas

There are several possibilities. The most interesting, I think, is the possibility of finding extra-solar planets which are earth-like. Already, the French have launched the Corot satellite into orbit, which is designed to look for earth-like planets in space. Next year, in 2008, the US sends Kepler into orbit, which may eventually find hundreds of earth-like twins in space. The discovery of earth-like planets may happen very soon, most likely within the next few years.

Once scientists identify earth-like planets in space, then astronomers and the SETI people will focus their telescopes and instruments onto these planets, and we might be able to detect the presence of oxygen and maybe even organic chemicals. It is probable that within about a decade, we might be able to identify earth-like planets with liquid oceans, which would be an exciting possibility. And the SETI people hope that they might be able to detect radio signals from intelligent life on these planets. However, this might take many more decades. By late in this century, we will have identified hundreds of such planets, so the probability that one of them might use radio signals for communication is small, but cannot be dismissed. So, before the end of this century, there is a distinct possibility that we may detect the first signs of intelligent life in space.

There is also the possibility of finding microbial life on Mars, but every year, this hope becomes dimmer and dimmer. Perhaps the new probe sent to Mars which will analyze the polar ice caps will have better luck.

There is the chance that Europa, a moon of Jupiter, may harbor life under the ice sheet, in its oceans, but it will take decades before we can send a space craft to Europa that can drill into the ice and send a submarine to explore for marine life.

Has string theory advanced in the past five years? Are there any big, make or break tests on the horizon that could prove or disprove the theory?
Adam H.
Boston, Massachusetts

String theory has gone through many phases of development since it began in 1968 by accident. Once every 10 years or so, we have a new stunning breakthrough which changes the very nature of the theory. Hence, perhaps we are due for another such breakthrough. (In between these breakthroughs, the cynics and critics begin to come out every time and criticize the theory. I am not worried, since new breakthroughs are around the corner. I personally believe that string theory is not in its final form, so the next breakthrough might be to reveal its true nature).

Meanwhile, several experiments are being done which can probe the periphery of the theory.
a) The Large Hadron Collider gets turned on in 2008, and it may find a host of new particles that are found in string theory, such as sparticles (super particles) and mini black holes. The discovery of these new types of particles won’t completely verify string theory, but it will go a long way to convincing the critics that we are on the right track.

b) In the next decade and beyond, LISA and the BBO (Big Bang Observer) go up into orbit, and they may detect gravity waves from the instant of creation. Various pre-big bang theories predict the spectrum of radiation emitted after the big bang, so by detecting this radiation and checking it against these theories, we can begin to eliminate some of them. In this way, pre-big bang physics might become one of the most important ways of probing string theory.

c) On-going experiments may detect a deviation from Newton’s inverse square law, which would signal the presence of another dimension. One experiment, at the Univ. of Colorado, turned out negative. But maybe this just means there is no parallel universe in Colorado.

d) Dark matter may soon be captured in one of our particle detectors. String theory predicts that dark matter is made of sparticles of high mass, so the detection of dark matter may verify some string theory predictions.

e) Various groups have predicted anomalies in cosmic ray physics due to string-induced particles being produced in the upper atmosphere. So on-going cosmic ray experiments might pick up these string theory-induced anomalies.

Is there sound in space? If an astronaut (space walking) bangs a tool against the aircraft – does that make a sound? The afterburners on a spacecraft – does that make a sound?
Jason Walker

There is no sound in outer space, since sound waves are waves of compression in our atmosphere, and there is no air in outer space. However, vibrations are definitely felt by the astronauts, and they can certainly hear noises within the rocket itself. So an astronaut who is space walking would hear sounds within his helmet and feel vibrations as he makes repairs, but he cannot hear sounds in the usual sense.