The art and beauty of general relativity

Margaret Wertheim, University of Melbourne

One hundred years ago this month, an obscure German physicist named Albert Einstein presented to the Prussian Academy of Science his General Theory of Relativity. Nothing prior had prepared scientists for such a radical re-envisioning of the foundations of reality.

Encoded in a set of neat compact equations was the idea that our universe is constructed from a sort of magical mesh, now known as “spacetime”. According to the theory, the structure of this mesh would be revealed in the bending of light around distant stars.

To everyone at the time, this seemed implausible, for physicists had long known that light travels in straight lines. Yet in 1919 observations of a solar eclipse revealed that on a cosmic scale light does bend, and overnight Einstein became a superstar.

Einstein is said to have reacted nonchalantly to the news that his theory had been verified. When asked how he’d have reacted if it hadn’t been, he replied: “I would have felt sorry for the dear Lord. The theory is correct.”

What made him so secure in this judgement was the extreme elegance of his equations: how could something so beautiful not be right?

The quantum theorist Paul Dirac would latter sum up this attitude to physics when he borrowed from poet John Keats, declaring that, vis-à-vis our mathematical descriptions of nature, “beauty is truth, and truth beauty”.

Art of science

A quest for beauty has been a part of the tradition of physics throughout its history. And in this sense, general relativity is the culmination of a specific set of aesthetic concerns. Symmetry, harmony, a sense of unity and wholeness, these are some of the ideals general relativity formalises. Where quantum theory is a jumpy jazzy mash-up, general relativity is a stately waltz.

As we celebrate its centenary, we can applaud the theory not only as a visionary piece of science but also as an artistic triumph.

What do we mean by the word “art”?

Lots of answers have been proposed to this question and many more will be given. A provocative response comes from the poet-painter Merrily Harpur, who has noted that “the duty of artists everywhere is to enchant the conceptual landscape”. Rather than identifying art with any material methods or practices, Harpur allies it with a sociological outcome. Artists, she says, contribute something bewitching to our mental experience.

It may not be the duty of scientists to enchant our conceptual landscape, yet that is one of the goals science can achieve; and no scientific idea has been more enrapturing than Einstein’s. Though he advised there’d never be more than 12 people who’d understand his theory, as with many conceptual artworks, you don’t have to understand all of relativity to be moved by it.

There is a beauty in spacetime. NASA, CC BY-NC

In essence the theory gives us a new understanding of gravity, one that is preternaturally strange. According to general relativity, planets and stars sit within, or withon, a kind of cosmic fabric – spacetime – which is often illustrated by an analogy to a trampoline.

Imagine a bowling ball sitting on a trampoline; it makes a depression on the surface. Relativity says this is what a planet or star does to the web of spacetime. Only you have to think of the surface as having four dimensions rather than two.

Now applying the concept of spacetime to the whole cosmos, and taking into account the gravitational affect of all the stars and galaxies within it, physicists can use Einstein’s equations to determine the structure of the universe itself. It gives us a blueprint of our cosmic architecture.

Synthesis

Einstein began his contemplations with what he called gedunken (or thought) experiments; “what if?” scenarios that opened out his thinking in wildly new directions. He praised the value of such intellective play in his famous comment that “imagination is more important than knowledge”.

The quote continues with an adage many artists might endorse: “Knowledge is finite, imagination encircles the world.”

But imagination alone wouldn’t have produced a set of equations whose accuracy has now been verified to many orders of magnitude, and which today keeps GPS satellites accurate. Thus Einstein also drew upon another wellspring of creative power: mathematics.

As it happened, mathematicians had been developing formidable techniques for describing non-Euclidean surfaces, and Einstein realised he could apply these tools to physical space. Using Riemannian geometry, he developed a description of the world in which spacetime becomes a dynamic membrane, bending, curving and flexing like a vast organism.

Where the Newtonian cosmos was a static featureless void, the Einsteinian universe is a landscape, constantly in flux, riven by titanic forces and populated by monsters. Among them: pulsars shooting out giant jets of x-rays and light-eating black holes, where inside the maw of an “event horizon”, the fabric of spacetime is ripped apart.

One mark of an important artist is the degree to which he or she stimulates other creative thinkers. General relativity has been woven into the DNA of science fiction, giving us the warp drives of Star Trek, the wormhole in Carl Sagan’s Contact, and countless other narrative marvels. Novels, plays, and a Philip Glass symphony have riffed on its themes.

At a time when there is increasing desire to bridge the worlds of art and science, general relativity reminds us there is artistry in science.

Creative leaps here are driven both by playful speculation and by the ludic powers of logic. As the 19th century mathematician John Playfair remarked in response to the bizzarities of non-Euclidean geometry, “we become aware how much further reason may sometimes go than imagination may dare to follow”.

In general relativity, reason and imagination combine to synthesise a whole that neither alone could achieve.

Margaret Wertheim, Vice-Chancellor’s Fellow in Science Communication, University of Melbourne

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

Why is Einstein’s general relativity such a popular target for cranks?

Michael J. I. Brown, Monash University

Scientists maybe celebrating the 100th anniversary of Albert Einstein’s general theory of relativity, but there was also a death in 1915. It was one of the many deaths of simple and intuitive physics that has happened over the past four centuries.

Today the concepts and mathematics of physics are often removed from everyday experience. Consequently, cutting edge physics is largely the domain of professional physicists, with years of university education.

But there are people who hanker for a simpler physics, toiling away on their own cosmologies. Rightly or wrongly, these people are often labelled cranks, but their endeavours tell us much misconceptions about science, its history and what it should be.

I regularly browse open access website arxiv.org to look for the latest astrophysics research. Real astrophysics, that is. But if I want to take a look at what pseudoscientists are up to, I can browse vixra.org. That’s right, “arxiv” backwards. The vixra.org website was founded by “scientists who find they are unable to submit their articles to arXiv.org” because that website’s owners filter material they “consider inappropriate”.

There are more than 1,800 articles on vixra.org discussing relativity and cosmology, and many don’t like relativity at all. Perhaps one reason why cranks particularly dislike relativity is because it is so unlike our everyday experiences.

Einstein predicted that the passage of time is not absolute, and can slow for speeding objects and near very massive bodies such as planets, stars and black holes. Over the past century, this bizarre predication has been measured with planes, satellites, and speeding muons.

But the varying passage of time is nothing like our everyday experience, which isn’t surprising as we don’t swing by black holes on our way to the shops. Everyday experience is often central to cranky ideas, with the most extreme example being flat earthers.

Thus many crank theories postulate that time is absolute, because that matches everyday experience. Of course, these crank theories are overlooking experimental data, or at least most of it.

History and linearity

One of the most curious aspects of pseudoscience is an oddly linear approach to science. To be fair, this can result from an overly literal approach to popular histories of science, which emphasise pioneering work over replication.

A pivotal moment in relativity’s history is Albert Michelson and Edward Morley’s demonstration that the speed of light didn’t depend on its direction of travel nor the motion of the Earth.

Of course, since 1887 the Michelson-Morley experiment has been confirmed many times. Modern measurements have a precision orders of magnitude better than the original 1887 Michelson-Morley experiment, but these don’t feature prominently in popular histories of science.

Interestingly many pseudoscientists are fixated on the original Michelson-Morley experiment, and how it could be in error. This fixation assumes science is so linear that the downfall a 19th century experiment will rewrite 21st century physics. This overlooks how key theories are tested (and retested) with a myriad of experiments with greater precision and different methodologies.

Another consequence of the pseudoscientific approach to history is that debunked results from decades past are often used by buttress pseudoscientific ideas. For example, many pseudoscientists claim Dayton Miller detected “aether drift” in the 1930s. But Miller probably underestimated his errors, as far more precise studies in subsequent decades did not confirm his findings.

Unfortunately this linear and selective approach to science isn’t limited to relativity. It turns up in cranky theories ranging from evolution to climate.

Climate scientist Michael E Mann is still dealing with cranky accusations about his seminal 1998 paper on the Earth’s temperature history, despite the fact it has been superseded by more recent studies that achieve comparable results. Indeed, it devoured so much of Mann’s time he has literally written a book about his experience.

What about the maths?

During the birth of physics, one could gain insights with relatively simple (and beautiful) mathematics. My favourite example is Johannes Kepler’s charting of the orbit of Mars via triangulation.

In the 17th century, Johannes Kepler used elegantly simple mathematics to chart the motion of Mars. Johannes Kepler / University of Sydney

Over subsequent centuries, the mathematics required for new physical insights has become more complex, as illustrated by Newton’s use of calculus and Einstein’s use of tensors. This level of mathematics is rarely in the domain of the enthusiastic but untrained amateur? So what do they do?

One option is to hark back to an earlier era. For example, trying to disprove general relativity by using the assumptions of special relativity or even Newtonian physics (again, despite the experiments to the contrary). Occasionally even numerology makes an appearance.

Another option is arguments by analogy. Analogies are useful when explaining science to a broad audience, but they aren’t the be-all and end-all of science.

In pseudoscience, the analogy is taken to the point of absurdity, with sprawling articles (or blog posts) weighed down with laboured analogies rather than meaningful analyses.

Desiring simplicity but getting complexity

Perhaps the most fascinating aspect of pseudoscientific theories is they hark for simplicity, but really just displace complexity.

A desire for naively simple science can produce bizarrely complex conclusions, like the moon landing hoax conspiracy theories. NASA/flickr

Ardents of the most simplistic pseudoscientific theories often project complexity onto the motives of professional scientists. How else can one explain scientists ignoring their brilliant theories? Claims of hoaxes and scams are commonplace. Although, to be honest, even I laughed out loud the first time I saw someone describe dark matter was a “modelling scam”.

Again, this isn’t limited to those who don’t believe in relativity. Simple misunderstandings about photography, lighting and perspective are the launch pad for moon landing conspiracy theories. Naively simple approaches to science can lead to complex conspiracy theories.

Changing intuition

Some have suggested that pseudoscience is becoming more popular and the internet certainly aids the transmission of nonsense. But when I look at history I wonder if pseudoscience will decay.

In the 19th century, Samuel Rowbotham promoted Flat Earthism to large audiences via lectures that combined wit and fierce debating skills. Perhaps in the 19th century a spherical world orbiting a sun millions of kilometres away didn’t seem intuitive.

But today we can fly around the globe, navigate with GPS and Skype friends in different timezones. Today, a spherical Earth is far more intuitive than it once was, and Flat Earthism is the exemplar of absurd beliefs.

Could history repeat with relativity? Already GPS utilises general relativity to achieve its amazing precision. A key plot device in the movie Interstellar was relativistic time dilation.

Perhaps with time, a greater exposure to general relativity will make it more intuitive. And if this happens, a key motivation of crank theories will be diminished.

Will general relativity become more widely understood via popular media, such as the movie Interstellar?

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Michael will be on hand for an Author Q&A between 4 and 5pm AEDT on Tuesday, November 24, 2015. Post your questions in the comments section below.

Michael J. I. Brown, Associate professor, Monash University

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

 

Common sense fallacy

by Tim Harding

The American writer H L Mencken once said “There is always a well-known solution to every human problem — neat, plausible, and wrong.” He was referring to ‘common sense’, which can be superficially plausible and sometimes right, but often wrong.

The Common Sense Fallacy (or ‘Appeal to Common Sense’) is superficially similar to the Argument from Popularity and/or  the Argument from Tradition. However, it differs from these fallacies by not necessarily relying on popularity or tradition.

Instead, common sense relies on the vague notion of ‘obviousness’, which means something like ‘what we perceive from personal experience’ or ‘what we should know without having had to learn.’ In other words, common sense is not necessarily supported by evidence or reasoning. As such, beliefs based on common sense are unreliable.  The fallacy lies in giving too much weight to common sense in drawing conclusions, at the expense of evidence and reasoning.

In some ways, scientific methods have been developed to avoid the errors that can result from common sense. For instance, common sense used to tell us that the Earth is flat and that the Sun revolves around the Earth – because that is the way things appear to us without scientific investigation.  Another example of ‘common sense’ is that the world appears to have been designed, so therefore there must have been a designer.

Einstein’s theories of relativity were initially resisted, even by the scientific community, because they defied common sense.  They seemed to belong more in the realm of science fiction than reality, until they were later verified by scientific observations.  Our modern Global Positioning System (GPS) now uses Einstein’s relativity theories.  This initial resistance may have led Einstein to later say that ”Common sense is nothing more than a deposit of prejudices laid down by the mind before you reach eighteen” .

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