*** Quantum Zoo by Marcus Chown

This is actually a light read for such a weighty topic – quantum physics. Chown does an admirable job of presenting complex issues in an easy to comprehend manner so you can appreciate the insight of the discoverer.

It is a remarkable fact that 99.9999999999999999% of the volume of ordinary matter is empty space. If there were some way to squeeze all the empty space out of the atom (making everything into neutrons), humanity could be squeezed into the space occupied by a sugar cube. P3

A proton is about 2000 times more massive than an electron. According to Heisenberg uncertainty principle, if a proton and an electron are confined in the same volume, the electron will be moving about 2000 times faster… But atoms atoms aren’t just 2000 times bigger than their nuclei, they’re more like 100,000 times bigger. Why? The electron is held by the relatively weak electric force, while the protons and neutrons in the nucleus are held together by the strong nuclear force, which is 50 times stronger. P45 For those keeping score at home: 50x2000=100,000

The Bose-Einstein helium superfluid can flow through impossibly small holes that no other liquid can flow through. It is also the only liquid that can flow uphill… All the atoms in the superfluid move together or they don’t move at all. Consequently, if superfluid is put in a bucket and the bucket is spun, it has no means open to it to attain the spin of the bucket. Instead it stays stubbornly still while the bucket spins around it… It has no viscosity. P81

Surely you’re aware that gravity accelerates all objects equally regardless of their mass, right? So if you drop a small stool and a heavy fridge together, they will strike the earth simultaneously (ignoring air resistance). What happens, however, if you place these items on an icerink surface, and then try to push them with exactly the same force? Won’t the stool shoot off much faster than the fridge? So despite the wildly different masses, why do the stool and fridge accelerate to the ground at exactly the same speed? Now, perhaps you appreciate the central peculiarity of gravity. A big mass must therefore experience a bigger a force, and that force must be in direct proportion to its mass. [Okay, genius, this is about as far as Newton got.] But how does gravity adjust itself to the mass it is acting on? To figure that out, you’d have to be a real genius, like Einstein. P120

Gravity only arises when a body is prevented from following its natural motion. Our natural motion on the Earth is free fall towards the center of the planet. The ground thwarts us, so we feel its force on our bodies… Most people therefore assume that astronauts orbiting earth are weightless because there is no gravity in space. However even at 500km above the earth, gravity is still 85% of that on the surface. So why are the astronauts weightless? The real reason is that their spacecraft is in free fall, and never hits the ground because their orbit allows them to move in a circle at the same rate as they fall. Gravity is still there (85% of it), they just can’t ‘feel’ it. P127

Believe it or not, the cosmic background radiation created at the birth of universe during the Big Bang epoch accounts for an astonishing 99% of light in today’s universe… That means that 1% of the static on your TV, is actually coming from the Big Bang! P141

If the universe were infinitely large and old, and evenly populated with stars, then one very obvious fact that would come from this, would be the fact that the night sky would be infinitely bright and blinding. Why? Because when we look up at any point in the sky, we would eventually see a star, no matter how far away, and the light from this star would eventually hit the earth (since the universe is infinitely old, the star’s light has been traveling forever already to reach us), so every point in the sky will be radiating light. The way out of this paradox is the fact that the universe cannot in fact exist forever and be infinitely large. P148