Albert Einstein, whose general theory of relativity is still fueling new work. Photo: -/AFP/Getty Images
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What’s up with gravity?

Cheer the discovery of the gravitational wave when it happens. But don’t be fooled: gravity will remain our greatest mystery for a long time yet.

Get ready for a lot of Einstein love. This year marks the centenary of Einstein’s general theory of relativity, which describes how gravity works. Sort of.

It does enough, for instance, to predict the existence of gravitational waves – ripples in space caused by objects moving within it. Not that we have ever seen one. US scientists have just celebrated the completion of their latest gravitational wave detector, which will turn on later this year. They hope to use them to spot the shaking caused by cataclysmic events, such as the collision of two black holes or a supernova explosion.

No one doubts that the waves do exist. Whether our detectors will prove sensitive enough to see them is another matter. Even if they do, it will be a hollow victory. General relativity will have ticked another box but it won’t advance our basic understanding of how gravity works. The truth is that this remains a mystery.

What we do know is that when you throw a ball up in the air, it returns to earth. That’s because the ball and the earth possess a quality called mass: a way of quantifying how difficult it is to accelerate something, to get that ball moving, or to change its path, or stop it. We can describe how something that has mass will move under the influence of something else with mass by calculating the geometry of the object’s gravitational field using Einstein’s mathematics.

Put simply, anything with mass warps the space (and time) around it, and an object travelling through this warped space follows a curved path. In the case of the ball, that means falling back down to earth. In the case of the earth moving past the sun, it means moving in an elliptical orbit rather than a line. After this, we’re hand-waving. Yes, we can do calculations and we can make predictions of phenomena that this warping of space and time will create. But gravity remains our least-understood force – by a very long way.

Take its weakness. The ball falls to earth, but a fridge magnet doesn’t fall off the fridge, even with the mass of the whole planet pulling on it. That’s seven million billion billion kilos losing out to a magnet the size of a coin. If you want to write down how much stronger than gravity the electromagnetic force is, you’ll need a 1 and 40 zeroes.

What’s more, our theory of magnets is much more complete than our theory of gravity. Gravity aside, we can describe all the forces using a mathematical description known as quantum field theory – a framework that lays out how energy, mass, space and time work together to create the forces we see in the universe. According to this theory, particles borrow energy thanks to the “uncertainty principle” of quantum mechanics, using it to create particles that pop in and out of existence. This is no flight of fancy: these “virtual” particles have been found for all the forces. They are the photon, the gluon and the W, Z and Higgs particles.

But we haven’t come close to finding anything that would constitute the “graviton”. Although we can understand the basic electromagnetic and nuclear forces that give us atoms, chemistry and all our electronic gadgets, we don’t have a bottom-up understanding of why a ball falls back to earth.

So cheer the discovery of the gravitational wave when it happens. But don’t be fooled: gravity will remain our greatest mystery for a long time yet.

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 27 May 2015 issue of the New Statesman, Saying the Unsayable

Artie Limmer/Texas Tech University
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Meet the evangelical Christian persuading believers that climate change is real

Katharine Hayhoe's Canadian missionary parents told her science and God were compatible. Then she moved to Texas. 

During Donald Trump’s presidential campaign, alarm rose with each mention of climate change. Denial, dismissal and repeated chants of “hoax” left no doubt as to his position.

Now President Trump’s withdrawal from the Paris Agreement has been seen as a seminal moment in the fight against climate change - one which many fear could lose the battle ahead of humanity.

But one scientist has been fighting a war of her own on the ground, against those who typically doubt the facts about global warming more than most - the evangelical Christian population of America.

And to make matters even more unusual, Katharine Hayhoe herself is an evangelical Christian who lives in the indisputably "bible belt" of Lubbock, Texas.

The atmospheric scientist has been named one of Time magazine's 100 most influential people and one of Politico’s 50 thinkers transforming American politics. Now she is using her considerable heft to speak to those who are hardest to convince that there is a manmade problem that threatens the Earth’s future.

I meet her at the science and music festival Starmus in Trondheim, Norway, where she is to address the attendees on Thursday in a talk entitled "Climate Change: Facts and Fictions".

Hayhoe was born in Canada, to missionary parents. Her father, a former science educator, showed her that there was no conflict between the ideas of God and science. However, it was something of a surprise to her when she discovered her pastor husband, whom she married in 2000, did not feel the same about climate change. It took her two years to convince him.

What started as a conversation became an organised project when she moved to America's South in the mid 2000s. 

“Moving to Lubbock was a culture shock," she tells me. "When I moved there I wasn’t doing much outreach, but it moved me in that direction.

“Lubbock is very conservative. It’s small and isolated.

“I would say the majority of people in Lubbock are either dismissive or doubtful about climate change. I was surrounded by people - neighbours, parents of friends, people at church, colleagues down the hall in the university - who weren’t convinced.”

So Hayhoe, who works as an associate professor and director of the Climate Science Centre at Texas Tech University, set to work. She began to collect the responses she was seeing to the climate change discussion and prepare her counter-argument.

“When I talk to people who are doubtful, I try to connect with the values they already have," she says. “The greatest myth is the myth of complacency - that ‘it doesn’t really matter to me’.

"But I would say that the second most insidious myth is that you only care about this issue if you’re a certain type of person. If you’re a green person, or a liberal person, or a granola person."

The stereotypes mean that people outside that demographic feel "I can't be that kind of person because that's not who I am", as she puts it.

Hayhoe convinced her husband using data, but rather than repeating a formula, she tries to find out what will resonate with different people: "For many groups, faith is a core value that people share.”

Whether she’s speaking to city planners, water company managers, school kids or Bible believers, Hayhoe says her hook is not the facts, but the feelings.

“I recently talked to arborists," she says. "For them, trees and plants are important, so I connect with them on that, and say ‘because we care about trees, or because we care about water or what the Bible says then let me share with you from the heart why I can about these issues because it affects something that you already care about’.

“My angle is to show people that they don’t need to be a different person at all - exactly who they already are is the kind of person who can care about climate change.”

Hayhoe came to public attention in the United States after appearing in a Showtime series on climate change. She has appeared on panels with Barack Obama and Leonardo DiCaprio, and launched a web series. As well as plaudits, this level of fame has also earned her daily threats and online abuse. 

“My critics think they’re coming from a position of religion, but they aren’t," she says. "They’re actually coming from a very specific political ideology which believes that the government should not have control over people’s lives in any way shape or form - very libertarian, free market, free economy, Tea Party."

She believes that in the United States, faith and politics has been conflated to the point "people can no longer tell the difference". 

“Now it’s conservatism that informs religion," she elaborates. "If the two are in conflict - like the Bible says God has given us responsibility over everything on this earth - then people say ‘oh, we can’t affect something as big as this Earth, God will take care of it anyway’."

Around half of those who attack her on social media identify themselves as Christians, she notes, but almost all call themselves conservatives. 

As a scientist, she’s been preparing data herself - naturally - on her online attackers, with depressingly familiar results.

“As soon as you stick your head out of the trench, you get it. There have been papers published showing that white men disproportionately form up that small group of dismissives. They’re almost all men. When I track my social media comments, I would say that 99.5 per cent of them are white men.

“Out of 1,000 negative comments, I have maybe five from women.”

After the climate change argument moved up a gear - following the Paris withdrawal - Hayhoe admits that she and her fellow scientists are concerned, although she pays tribute to the businesses, cities and states from the US that have committed to following the Paris agreement themselves.

On the subject of the chief white male denier, Trump himself, Hayhoe says she has a discussion point which she feels may convince him to think carefully about his role in the fight against global warming’s impact on humanity.

“I would attempt to connect with the values that he has and show him how acting on this would be in his best interests," she says.

“One guess would be ‘what do you want your legacy to be? What do you want to be known as, the man who destroyed the world, or the man who saved it?’”

Katharine Hayhoe is speaking at Starmus on Thursday June 22. For more details, visit Starmus.

Kirstie McCrum is a freelance journalist. Follow her @kirstiemccrum.

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