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Einstein has had a good month, all things considered. His century-old prediction, that the very fabric of space and time can support waves travelling at light-speed, was confirmed by the LIGO collaboration. More, the bizarre and horrifying consequences of his theory of gravity, the singularly-collapsed stars that came to be called ‘black holes’, have been directly detected for the first time.

The post Questions, questions, questions… appeared first on OUPblog.

The remarkable detection of gravitational waves by the LIGO collaboration recently has drawn much attention to the fundamental and intriguing workings of gravity in our universe. Finding these gravitational waves, inferred to be produced by merger of two stellar mass black holes, has been like listening to the very distant sound of the universe.

The post What black hole collisions reveal about the universe appeared first on OUPblog.

The discovery of gravitational waves, announced on 11 February 2016 by scientists from the Laser Interferometer Gravitational-wave Observatory (LIGO), has made headline news around the world. One UK broadsheet devoted its entire front page to a image of a simulation of two orbiting black holes on which they superimposed the headline "The theory of relativity proved".

The post When black holes collide appeared first on OUPblog.

Quasars are distant galactic nuclei generating spectacular amounts of energy by matter accretion onto their central supermassive black holes. The precise geometry and origin of this huge activity are still largely unknown, and direct spatial resolution of the emitting regions from such distant monsters is not currently possible.

The post An efficient way to find monsters with two faces appeared first on OUPblog.

A couple of days after seeing Christopher Nolan’s Interstellar, I bumped into Sir Roger Penrose. If you haven’t seen the movie and don’t want spoilers, I’m sorry but you’d better stop reading now.

Still with me? Excellent.

Some of you may know that Sir Roger developed much of modern black hole theory with his collaborator, Stephen Hawking, and at the heart of Interstellar lies a very unusual black hole. Straightaway, I asked Sir Roger if he’d seen the film. What’s unusual about Gargantua, the black hole in Interstellar, is that it’s scientifically accurate, computer-modeled using Einstein’s field equations from General Relativity.

Scientists reckon they spend far too much time applying for funding and far too little thinking about their research as a consequence. And, generally, scientific budgets are dwarfed by those of Hollywood movies. To give you an idea, Alfonso Cuarón actually told me he briefly considered filming Gravity in space, and that was what’s officially classed as an “independent” movie. For big-budget studio blockbuster Interstellar, Kip Thorne, scientific advisor to Nolan and Caltech’s “Feynman Professor of Theoretical Physics”, seized his opportunity, making use of Nolan’s millions to see what a real black hole actually looks like. He wasn’t disappointed and neither was the director who decided to use the real thing in his movie without tweaks.

Black holes are so called because their gravitational fields are so strong that not even light can escape them. Originally, we thought these would be dark areas of the sky, blacker than space itself, meaning future starship captains might fall into them unawares. Nowadays we know the opposite is true – gravitational forces acting on the material spiralling into the black hole heat it to such high temperatures that it shines super-bright, forming a glowing “accretion disk”.

The computer program the visual effects team created revealed a curious rainbowed halo surrounding Gargantua’s accretion disk. At first they and Thorne presumed it was a glitch, but careful analysis revealed it was behavior buried in Einstein’s equations all along – the result of gravitational lensing. The movie had discovered a new scientific phenomenon and at least two academic papers will result: one aimed at the computer graphics community and the other for astrophysicists.

I knew Sir Roger would want to see the movie because there’s a long scene where you, the viewer, fly over the accretion disk–not something made up to look good for the IMAX audience (you have to see this in full IMAX) but our very best prediction of what a real black hole should look like. I was blown away.

Some parts of the movie are a little cringeworthy, not least the oft-repeated line, “that’s relativity”. But there’s a reason for the characters spelling this out. As well as accurately modeling the black hole, the plot requires relativistic “time dilation”. Even though every physicist has known how to travel in time for over a century (go very fast or enter a very strong gravitational field) the general public don’t seem to have cottoned on.

Most people don’t understand relativity, but they’re not alone. As a science editor, I’m privileged to meet many of the world’s most brilliant people. Early in my publishing career I was befriended by Subramanian Chandrasekhar, after whom the Chandra space telescope is now named. Penrose and Hawking built on Chandra’s groundbreaking work for which he received the Nobel Prize; his The Mathematical Theory of Black Holes (1954) is still in print and going strong.

When visiting Oxford from Chicago in the 1990s, Chandra and his wife Lalitha would come to my apartment for tea and we’d talk physics and cosmology. In one of my favorite memories he leant across the table and said, “Keith – Einstein never actually understood relativity”. Quite a bold statement and remarkably, one that Chandra’s own brilliance could end up rebutting.

Space is big – mind-bogglingly so once you start to think about it, but we only know how big because of Chandra. When a giant sun ends its life, it goes supernova – an explosion so bright it outshines all the billions of stars in its home galaxy combined. Chandra deduced that certain supernovae (called “type 1a”) will blaze with near identical brightness. Comparing the actual brightness with however bright it appears through our telescopes tells us how far away it is. Measuring distances is one of the hardest things in astronomy, but Chandra gave us an ingenious yardstick for the Universe.

In 1998, astrophysicists were observing type 1a supernovae that were a very long way away. Everyone’s heard of the Big Bang, the moment of creation of the Universe; even today, more than 13 billion years later, galaxies continue to rush apart from each other. The purpose of this experiment was to determine how much this rate of expansion was slowing down, due to gravity pulling the Universe back together. It turns out that the expansion’s speeding up. The results stunned the scientific world, led to Nobel Prizes, and gave us an anti-gravitational “force” christened “dark energy”. It also proved Einstein right (sort of) and, perhaps for the only time in his life, Chandra wrong.

Why Chandra told me Einstein was wrong was because of something Einstein himself called his “greatest mistake”. When relativity was first conceived, it was before Edwin Hubble (after whom another space telescope is named) had discovered space itself was expanding. Seeing that the stable solution of his equations would inevitably mean the collapse of everything in the Universe into some “big crunch”, Einstein devised the “cosmological constant” to prevent this from happening – an anti-gravitational force to maintain the presumed status quo.

Once Hubble released his findings, Einstein felt he’d made a dreadful error, as did most astrophysicists. However, the discovery of dark energy has changed all that and Einstein’s greatest mistake could yet prove an accidental triumph.

Of course Chandra knew Einstein understood relativity better than almost anyone on the planet, but it frustrates me that many people have such little grasp of this most beautiful and brilliant temple of science. Well done Christopher Nolan for trying to put that right.

Interstellar is an ambitious movie – I’d call it “Nolan’s 2001” – and it educates as well as entertains. While Matthew McConaughey barely ages in the movie, his young daughter lives to a ripe old age, all based on what we know to be true. Some reviewers have criticized the ending – something I thought I wouldn’t spoil for Sir Roger. Can you get useful information back out of a black hole? Hawking has changed his mind, now believing such a thing is possible, whereas Penrose remains convinced it cannot be done.

We don’t have all the answers, but whichever one of these giants of the field is right, Nolan has produced a thought-provoking and visually spectacular film.

Image Credit: “Best-Ever Snapshot of a Black Hole’s Jets.” Photo by NASA Goddard Space Flight Center. CC by 2.0 via Flickr.

The post That’s relativity appeared first on OUPblog.

       

Not sure why scientists are so ga-ga over figuring out what black holes really are. I’ve already done that. And I know how they are formed. Revisions = black holes Revisions are formed when first drafts become second drafts, third drafts, fourth drafts, etc. An endless loop of deletions and additions that suck the writer…

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The realm of theoretical physics is teeming with abstract and beautiful concepts, and the process of bringing them into existence, and then explaining them, demands profound creativity according to Giovanni Vignale, author of The Beautiful Invisible: Creativity, imagination, and theoretical physics. In the excerpt below Vignale discusses the beginnings of theoretical physics and the abstract.

Physics, most of us would agree, is the basic science of nature. Its purpose is to discover the laws of the natural world. Do such laws exist? Well, the success of physics at identifying some of them proves, in retrospect, that they do exist. Or, at least, it proves that there are Laws of Physics, which we can safely assume to be Laws of Nature.

Granted, it may be difficult to discern this lofty purpose when all one hears in an introductory course is about flying projectiles and swinging pendulums, strings under tension and beams in equilibrium. But at the beginning of the enterprise there were some truly fundamental questions such as: the nature of matter, the character of the forces that bind it together, the origin of order, the fate of the universe. For centuries humankind had been puzzling over these questions, coming up with metaphysical and fantastic answers. And it stumbled, and it stumbled, until one day—and here I quote the great Austrian writer and ironist, Robert Musil:

. . . it did what every sensible child does after trying to walk too soon; it sat down on the ground, contacting the earth with a most dependable if not very noble part of its anatomy, in short, that part on which one sits. The amazing thing is that the earth showed itself uncommonly receptive, and ever since that moment of contact has allowed men to entice inventions, conveniences, and discoveries out of it in quantities bordering on the miraculous.

This was the beginning of physics and, actually, of all science: an orgy of matter-of-factness after centuries of theology. Careful and systematic observation of reality, coupled with quantitative analysis of data and an egregious indifference to theories that could not be tested by experiment became the hallmark of every serious investigation into the nature of things.

But even as they were busy observing and experimenting, the pioneers of physics did not fail to notice a peculiar feature of their discipline. Namely, they realized that the laws of nature were best expressed in an abstract mathematical language—a language of triangles and circles and limits—which, at first sight, stood almost at odds with the touted matter-of-factness of experimental science. As time went by, it became clear that mathematics was much more than a computational tool: it had a life of its own. Things could be discovered by mathematics. John Adams and, independently, Urbain Le Ferrier, using Newton’s theory of gravity, computed the orbit of Uranus and found that it deviated from the observed one. Rather than giving up, they did another calculation showing that the orbit of Uranus could be explained if there were another planet pulling on Uranus according to Newton’s law of gravity. Such a planet had never been seen, but Adams and Le Ferrier told the astronomers where to look for it. And, lo and behold, the planet—Neptune—was there, waiting to be discovered. That was in 1846.

Even this great achievement pales in comparison with things that happened later. In the 1860s, James Clerk Maxwell trusted mathematics—and not just the results of a calculation, but the abstract structure of a set of equations—to predict the existence of electromagnetic waves. And electromagnetic waves (of which visible light is an example) were controllably produced in the lab shortly afterwards.

In the 1870s Ludwig

With every revelation of the Hubble telescope, the universe appears ever more mind boggling. According to NASA, a massive black hole has been detected by the Hubble in the M84 galaxy:

"The Space Telescope Imaging Spectrograph measured a velocity of 880,000 mph within 26 light-years of the galaxy's center. This measurement allowed astronomers to calculate that the black hole contains at least 300 million solar masses. M84 is located in the Virgo Cluster of galaxies, 50 million light-years from Earth, and a nearby neighbor to the more massive M87 galaxy, which also contains an extremely massive black hole." (NASA)

Just think of it. We are but a speck in a quite small solar system "only" several hundred million miles across. Our solar system is among millions of other solar systems inside the Milky Way galaxy, which itself is only one among millions of other galaxies, of which M84 and M87 are just two. Those two galaxies are part of a cluster of galaxies called the Virgo Cluster, which itself is 50 million light years away from us.

That means it would take us 50 million years traveling at the speed of light (about186,000 miles per second) to get there. I would try to calculate the distance in miles. But I'm certain I'd drop too many zeroes. Perhaps even more amazingly, on top of it all, the black hole discovered inside galaxy M84 contains the masses of more than 300 million suns. And, get this, according to the NASA report, in the middle of that galaxy velocities of 880,000 miles per hour have been measured. Such high velocities are apparently used by scientists to detect the presence of a black hole.

Compared to the speed of light, 880,000 miles per hour is really way slow. But just think. Traveling at that speed, it would only take us around 15 minutes to get to our moon. This is definitely one of those "things that make you go "Hmmmm". The scope is almost beyond comprehension. If you ask me, in the overall scheme of things, whether or not the furniture got dusted this week is probably not worth worrying about.

Because absolutely no one demanded it, in this post, I am giving you a sneak peek into my artistic process, or lack thereof.

Inspiration hits me from just about anywhere, but typically it comes to me while I am no where near a pencil or piece of paper.

Thankfully for modern technology, I can just whip out my cell and take a picture of whatever tickles my imagination. And then sketch my idea later.

However for this piece, I did not have that luxury. My wife and I were traveling in a car when I spotted a really cool statue in front a public library.





So when I finally got home, I jumped on the net and luckily found a picture of it. I quickly sketched out my idea.