In his novel view, the same force that keeps us pinned to the ground also keeps us locked in a reality in which everything is tidy, unitary, and — for better and for worse — rooted in one place only. Aside from a frustrating inability to manifest in any number of places simultaneously, Penrose qualifies as something of a quantum phenomenon himself. There do indeed seem to be many Penroses; they just all happen to occupy the same body.
There is Penrose the puzzle master, creator of geometric illusions that M. Escher incorporated into some of his most famous works. There is Penrose the neuroscientist, who developed a controversial theory linking consciousness to quantum processes in the brain. And there is Penrose the author, most recently of a 1,page tome called The Road to Reality , which is modestly subtitled A Complete Guide to the Laws of the Universe.
On our second meeting, all of those Penroses are slumped on a sofa in the living room of his spacious home a few miles outside Oxford. A coffee cup and a plate of cookies rest on his chest, which, since he is sunk so deeply into the sofa, is almost perfectly horizontal. Tall windows look out on a lush green yard, damp from the rain. In this pensive setting, he looks back on the events that convinced him that quantum theory has serious problems, a view that would be heresy for a young physicist entering academia today.
The crucial moment came during a lecture by Paul Dirac, one of the legendary early thinkers in quantum mechanics.
To illustrate, he broke a piece of chalk in two and then tried to explain why you never saw superpositions in real life. My mind may have wandered briefly, because I never heard his explanation!
The maddening part of that problem is that the ability of particles to exist in two places at once is not a mere theoretical abstraction. It is a very real aspect of how the subatomic world works, and it has been experimentally confirmed many times over.
One of the clearest demonstrations comes from a classic physics setup called the double-slit experiment. Undergraduate major: Mathematics. Penrose graduated with first-class honors from University College London in John's College, Cambridge. Number of published papers: and counting.
Mentor: Astronomer Dennis Sciama, a leading s advocate of the steady-state theory, which held that the universe is eternal. Alternative career: While at University College London, Penrose was forced to choose between biology and mathematics. In this test, a beam of light is projected through two parallel slits cut in an opaque barrier and then onto a white screen.
When light hits the screen, it does not produce just two overlapping regions of brightness. Instead, something strange appears: a series of alternating light and dark stripes, called an interference pattern. The 19th-century explanation for this was that light is a wave and that light waves overlap after passing through the slits.
The light waves seem to behave much like water waves on the surface of a pond: Where two crests meet, the wave gets higher, creating a bright stripe; where a crest meets a trough, the two cancel out, and the wave vanishes, yielding a dark zone.
With the development of quantum theory in the early 20th century, the explanation became far weirder. Physicists realized that light is not a wave exactly but rather a wavelike particle called a photon. That discovery suggested a new experiment. In principle, it would be possible to send light through the slits one photon at a time and collect them on photographic film.
Common sense says there should be no interference pattern in this case: There is only one photon in the apparatus at any given moment, so there is nothing for the light to interfere with. How do black holes work? Penrose and physicist Stephen Hawking developed a detailed mathematical description of the gravitational collapse that produces black holes. Penrose developed the idea of cosmic censorship, which holds that information about processes happening within black holes remains forever hidden from outside observers.
Then in a young British physicist named Geoffrey Ingram Taylor actually ran the experiment and witnessed the bizarre result. As the photons accumulate on the film, the same old interference pattern of alternating brightand dark stripes gradually appears, defying common sense. In this case, there is only one thing each photon can interact with — itself. The only way this pattern could form is if each photon passes through both slits at once and then interferes with its alternate self.
It is as if a moviegoer exited a theater and found that his location on the sidewalk was determined by another version of himself that had left through a different exit and shoved him on the way out.
Quantum mechanics boasts all sorts of delightfully odd features. There's the fact that two separated particles can interact instantaneously, a phenomenon called quantum entanglement. Einstein disparaged the theory, which he called "spooky action at a distance," but there is significant evidence to support the theory of quantum entanglement. And there's another phenomenon called quantum superposition. This principle of quantum mechanics suggests that particles can exist in two separate locations at once.
Physicists from Stanford University have now demonstrated the superposition of a group of atoms over a greater distance than ever before : 54 centimeters, or about 1. Danish physicist Niels Bohr showed us that the orbits of electrons inside atoms are also quantized.
They come in predetermined sizes called energy levels. When an electron drops from a higher energy level to a lower energy level, it spits out a photon with an energy equal to the size of the gap.
Equally, an electron can absorb a particle of light and use its energy to leap up to a higher energy level. Astronomers use this effect all the time. We know what stars are made of because when we break up their light into a rainbow-like spectrum, we see colors that are missing. Different chemical elements have different energy level spacings, so we can work out the constituents of the sun and other stars from the precise colors that are absent. The sun makes its energy through a process called nuclear fusion.
It involves two protons — the positively charged particles in an atom — sticking together. However, their identical charges make them repel each other, just like two north poles of a magnet. Think of protons as particles and they just collide with the wall and move apart: No fusion, no sunlight.
So although it is unlikely to be where the leading edge is, it is there sometimes. Physicists call this effect "quantum tunneling".
Eventually fusion in the sun will stop and our star will die. Gravity will win and the sun will collapse, but not indefinitely. The smaller it gets, the more material is crammed together. Us giant beings are just going to have to sit in one place and watch the particles have all the fun. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
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