Carlo Rovelli

According to a new paper, white holes, the theoretical opposite of black holes, may account for dark matter, and may even predate the universe. They may even, according to Carlo Rovelli, explain the direction of time: A black hole is one prediction of Einstein’s theory of general relativity. Another is known as a white hole, which is like a black hole in reverse: Whereas nothing can escape from a black hole’s event horizon, nothing can enter a white hole’s event horizon. … In the 2014 study, Rovelli and his team suggested that, once a black hole evaporated to a degree where it could not shrink any further because space-time could not be squeezed into anything smaller, the dying black hole Read More ›

Carlo Rovelli, author of The Order of Time, that there is neither space nor time: A present that is common throughout the whole universe does not exist. Events are not ordered in pasts, presents, and futures; they are only “partially” ordered. There is a present that is near to us, but nothing that is “present” in a far-off galaxy. The present is a localized rather than a global phenomenon. The difference between past and future does not exist in the elementary equations that govern events in the world. It issues only from the fact that, in the past, the world found itself subject to a state that, with our blurred take on things, appears particular to us. Locally, time passes Read More ›

Further to Carlo Rovelli’s views on time travel (only a technological problem, not a scientific one) and the order of time in general,  views, as set out in The Order of Time, our color commentator Rob Sheldon offers, — If I can speculate about what goes on in physicist’s heads, this issue about time is an attempt to force symmetry on the universe. Sorta like the 2-yr old who wants to regularize irregular verbs. “Mommy not home; she goed to the store.” Einstein’s Special Relativity (SR) argued that time was a fourth dimension and should not be treated any differently than height, width, and length. To get the units right, one only needed to multiply time by the speed of light–c*t. Only Read More ›

Not a scientific one. Dan Falk interviews physicist Carlo Rovelli about “about the nature of time, whether it has a beginning and if humans might one day master time travel:” Could time travel ever be possible? Well, “time traveling” is what we do all our lives, isn’t it? But you mean, can we jump quickly to the past or to the future. Jumping to the far future is certainly possible. It’s only a technological problem, not a scientific one. One way is to move very fast. When you move fast, time passes very slowly for you — so if you could run fast enough around your house many times, you could do that in a time span which for you Read More ›

From Carlo Rovelli at Scientific American: Against Philosophy is the title of a chapter of a book by one of the great physicists of the last generation: Steven Weinberg.1 Weinberg argues eloquently that philosophy is more damaging than helpful for physics—it is often a straightjacket that physicists have to free themselves from. Stephen Hawking famously wrote that “philosophy is dead” because the big questions that used to be discussed by philosophers are now in the hands of physicists.2 Neil de Grasse Tyson publicly stated: “…we learn about the expanding universe, … we learn about quantum physics, each of which falls so far out of what you can deduce from your armchair that the whole community of philosophers … was rendered Read More ›

From Andrew Jaffe at Nature, reviewing Carlo Rovelli’s The Order of Time: According to theoretical physicist Carlo Rovelli, time is an illusion: our naive perception of its flow doesn’t correspond to physical reality. Indeed, as Rovelli argues in The Order of Time, much more is illusory, including Isaac Newton’s picture of a universally ticking clock. Even Albert Einstein’s relativistic space-time — an elastic manifold that contorts so that local times differ depending on one’s relative speed or proximity to a mass — is just an effective simplification. … Rovelli is one of the creators and champions of loop quantum gravity theory, one of several ongoing attempts to marry quantum mechanics with general relativity. In contrast to the better-known string theory, Read More ›