For years Albert Einstein insisted, like Aristotle and Newton before him, that the universe was a magnificent and immortal cathedral, fixed for all eternity. In this picture, time runs from the infinite past to the infinite future, and little changes in between. When a prominent Belgian scientist proposed in 1927 that the universe was growing like an expanding balloon, Einstein pronounced the idea “abominable.”
By 1931, however, the great physicist had been confronted with telescopic evidence that distant galaxies were in flight. Perhaps ever more convincing, his mathematical model for a static universe had been shown to be like a pencil balanced on its point: give it a tiny nudge and it starts to move. When he arrived in Pasadena, Einstein was ready to acknowledge a cosmos in flux. He told the small group of American scientists gathered in the cozy library of the Mount Wilson Observatory in their suits and their ties that the observed motion of the galaxies “has smashed my old construction like a hammerblow.” Then he swung down his hand to emphasize the point.
-- Alan Lightman
Last winter, a team of Caltech astronomers reported that two supermassive black holes appeared to be spiralling together toward a cataclysmic collision that could bring down the curtains in that galaxy.
The evidence was a rhythmic flickering from the galaxy’s nucleus, a quasar known as PF 1302-101, which Matthew Graham and his colleagues interpreted as the fatal mating dance of a pair of black holes with a total mass of more than a billion suns. Their merger, the astronomers calculated, could release as much energy as 100 million supernova ripples in space-time known as gravitational waves that would blow the stars out of that hapless galaxy like leaves on a roof.
The apocalypse is still on, apparently – at least in a galaxy about 3.5 billion light-years from here.
-- Dennis Overbye
Over the past hundred years, numerous experiments on elementary particles have upended the classical paradigm of a causal, deterministic universe. Consider, for example, the so-called double-slit experiment. We shoot a bunch of elementary particles – say, electrons – at a screen that can register their impact. But in front of the screen, we place a partial obstruction: a wall with two thin parallel vertical slits. We look at the resulting pattern of electrons on the screen. What do we see?
If the electrons were like little pellets (which is what classical physics would lead us to believe), then each of them would go through one slit or the other, and we would see a pattern of two distinct lumps on the screen, one lump behind each slit. But in fact we observe something entirely different: an interference pattern, as if two waves are colliding, creating ripples.
Astonishingly, this happens even if we shoot the electrons one by one, meaning that each electron somehow acts like a wave interfering with itself, as if it is simultaneously passing through both slits at once.
So an electron is a wave, not a particle? Not so fast. For if we place devices at the slits that “tag” the electrons according to which slit they go through (thus allowing us to know their whereabouts), there is no interference pattern. Instead, we see two lumps on the screen, as if the electrons, suddenly aware of being served, decided to act like little pellets.
To test their commitment to being particles, we can tag them as they pass through the slits – but then, using another device, erase the tags before they hit the screen. If we do that, the electrons go back to their wavelike behavior, and the interference pattern miraculously reappears.
-- Edward Frenkel
Sorry, Einstein, but ‘Spooky Action’ Seems Real.
Scientists at Delft University of Technology report that they have conducted an experiment that proves a fundamental claim of quantum theory – objects separated by a great distance instantaneously affect each other’s behavior.
The finding is another blow to standard physics, which states that an object is directly influenced only by its immediate surroundings. The study is further proof of a theory that Einstein rejected. He noted that quantum theory necessitated “spooky action at a distance,” and refused to accept the idea that the universe could behave in a strange and apparently random fashion.