One world is not enough

On inaccessible universes and infinite planets.

Don’t worry, there are other worlds. There have to be. If there aren’t, then we haven’t yet made sense of this one. On 19 June, the celebrated science-fiction writers Terry Pratchett and Stephen Baxter will publish a new book, The Long Earth. It is based on an outlandish premise: that an infinite number of variations on our planet are hidden in inaccessible universes. If it were just science fiction, we could either welcome or dismiss it, according to our taste, as yet another example of the limitless human imagination. The trouble is, the whole thing is based in evidence. Worse, this evidence is now the bedrock of modern science.

First of all, let’s go to the roots of our physical reality. If you fire an atom at a screen containing two openings, the atom will go through both. It’s not just atoms; a molecule composed of 60 or so atoms does the same thing. Anything that follows the laws of quantum theory will do it. The only time this doesn’t happen is when someone is watching.

That we don’t get into a car using all four doors at once tells us that the weirdness disappears once you have a lot more than a few dozen atoms clumped together. No one knows why, and it doesn’t change the fact that the strange behaviour of the building blocks of matter is capable of breaking your mind.

No one knew this better than Hugh Everett, who started his career trying to solve this puzzle and ended up a chain-smoking alcoholic. Everett’s idea is now known as the “many worlds” interpretation of quantum mechanics. According to this, a new universe is created every time a subatomic particle is faced with a choice of things to be or do. The ultimate logical consequence is that the universe is composed of myriad sub-universes, each subtly different from the one that spawned it. In this cornucopia of worlds, many will be utterly different from ours. There is, according to the theory, a world where Elvis Presley is the king, not of rock’n’roll, but of Great Britain and Northern Ireland.

No one accepted the idea, and Everett responded to the pain of rejection by slowly self-destructing. Today, however, physicists take these quantum worlds seriously. And they are not the only strange fruit of modern physics.

Our best theory of how the universe began requires that it went through a ridiculous period of super-fast expansion, increasing in size by a factor of 1,000 billion billion billion in a fraction of a millisecond. If that is the case, the same “inflation” mechanism will cause other universes to blow up from tiny instabilities in the fabric of our universe. They pinch off and float away beyond our reach. And if you believe Everett’s theory, the activity of quantum particles in each of those worlds will spawn ever more worlds nested within them.

Forget reality

It might seem as if the existence of these universes would be unverifiable, but that is a supposition which ignores the ingenuity of scientists. Some have already worked out what imprint a collision with one of the inflated universes would make on the microwave background radiation that fills our universe. Having figured that out, they are now combing the universe for signs that we have touched another world.

It will be harder to verify the existence of the many quantum worlds. Some believe a better explanation for quantum phenomena is that there is no objective reality at all; nothing exists until an experimental observation brings it into being. But clearly, whatever Pratchett and Baxter have come up with, it won’t be as strange or unbelievable as the truth. 

Michael Brooks’s “The Secret Anarchy of Science” is out now in paperback (Profile Books, £8.99)

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 18 June 2012 issue of the New Statesman, Drones: video game warfare

Davide Restivo at Wikimedia Commons
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Scientists have finally said it: alcohol causes cancer

Enough of "linked" and "attributable": a new paper concludes that alcohol directly causes seven types of cancer.

I don't blame you if you switch off completely at the words "causes cancer". If you pay attention to certain publications, everything from sunbeds, to fish, to not getting enough sun, can all cause cancer. But this time, it's worth listening.

The journal Addiction has published a paper that makes a simple, yet startling, claim: 

"Evidence can support the judgement that alcohol causes cancer of the oropharynx [part of the throat], larynx, oesophagus, liver, colon, rectum and [female] breast"

So what's especially significant about this? 

First, scientists, unlike journalists, are very wary of the word "causes". It's hard to ever prove that one action directly led to another, rather than that both happened to occur within the same scenario. And yet Jennie Connor, author of the paper and professor in the Preventive and Social Medicine department at the University of Otago, New Zealand, has taken the leap.

Second, alcohol not only causes cancer of one kind – the evidence supports the claim that it causes cancer at seven different sites in our bodies. There was weaker evidence that it may also cause skin, prostate and pancreatic cancer, while the link between mouth cancers and alcohol consumption was the strongest. 

What did we know about alcohol and cancer before?

Many, many studies have "linked" cancer to alcohol, or argued that some cases may be "attributable" to alcohol consumption. 

This paper loooks back over a decade's worth of research into alcohol and cancer, and Connor concludes that all this evidence, taken together, proves that alcohol "increases the incidence of [cancer] in the population".

However, as Connor notes in her paper, "alcohol’s causal role is perceived to be more complex than tobacco's", partly because we still don't know exactly how alcohol causes cancer at these sites. Yet she argues that the evidence alone is enough to prove the cause, even if we don't know exactly how the "biologial mechanisms" work. 

Does this mean that drinking = cancer, then?

No. A causal link doesn't mean one thing always leads to the other. Also, cancer in these seven sites was shown to have what's called a "dose-response" relationship, which means the more you drink, the more you increase your chances of cancer.

On the bright side, scientists have also found that if you stop drinking altogether, you can reduce your chances back down again.

Are moderate drinkers off the hook?

Nope. Rather devastatingly, Connor notes that moderate drinkers bear a "considerable" portion of the cancer risk, and that targeting only heavy drinkers with alcohol risk reduction campaigns would have "limited" impact. 

What does this mean for public health? 

This is the tricky bit. In the paper, Connor points out that, given what we know about lung cancer and tobacco, the general advice is simply not to smoke. Now, a strong link proven over years of research may suggest the same about drinking, an activity society views as a bit risky but generally harmless.

Yet in 2012, it's estimated that alcohol-attributable cancers killed half a million people, which made up 5.8 per cent of cancer deaths worldwide. As we better understand the links between the two, it's possible that this proportion may turn out to be a lot higher. 

As she was doing the research, Connor commented:

"We've grown up with thinking cancer is very mysterious, we don't know what causes it and it's frightening, so to think that something as ordinary as drinking is associated with cancer I think is quite difficult."

What do we do now?

Drink less. The one semi-silver lining in the study is that the quantity of alcohol you consume has a real bearing on your risk of developing these cancers. 

On a wider scale, it looks like we need to recalibrate society's perspective on drinking. Drug campaigners have long pointed out that alcohol, while legal, is one of the most toxic and harmful drugs available  an argument that this study will bolster.

In January, England's chief medical officer Sally Davies introduced some of the strictest guidelines on alcohol consumption in the world, and later shocked a parliamentary hearing by saying that drinking could cause breast cancer.

"I would like people to take their choice knowing the issues," she told the hearing, "And do as I do when I reach for my glass of wine and think... do I want to raise my risk of breast cancer?"

Now, it's beginning to look like she was ahead of the curve. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.