In science, no work is completed until it has been picked to pieces

Dangerous dithering.

What does a scientist have to do to convince you? The answer used to be “wait until his critics die” – hence the physicist Max Planck’s assertion that science advances one funeral at a time.

But sometimes even that is not enough. Late last month, the smell researcher Luca Turin published striking new evidence supporting an idea first put forward by Sir Malcolm Dyson in 1938. Dyson presented his “vibrational” theory of how our sense of smell works to universal apathy. Three generations later, scientists are still saying “meh”.

That year, 1938, was also when it was first argued that pumping carbon dioxide into the atmosphere would raise global temperatures. The idea came from the steam engineer Guy Stewart Callendar; the broad response was “implausible”. Today, in 2013, scientists have shifted: they generally agree that Callendar was right. Yet there remains a dangerous level of disagreement about the detail.

At least Turin’s scientific peers have presented him with a clear path to follow. Dyson’s idea was that when a molecule gets up our nose, its characteristic smell is created by the way the bonds within that molecule vibrate. In a clever piece of experimental work, Turin has shown that human beings can distinguish between two molecules that differ only in the way they vibrate. The two molecules tested were both cyclopentadecanone, but while one contained normal hydrogen atoms the other contained “deuterated” hydrogen, which has an added neutron in its atomic nucleus. The additional particle creates a difference in the way the molecules vibrate. And that is why, according to Turin, they smell different to us.

The experiment punches a hole in the accepted theory of smell, which says that smell experiences are triggered by differently shaped molecules fitting different receptors in the nose. This “lock and key” idea can’t explain why two identically shaped molecules smell different. But Turin’s critics said last month that before they will even consider accepting his theory, they want him to show exactly what goes on in human smell receptors.

They are right to make such demands. This is science, where no work is finished until it has been picked to pieces. But that is exactly why it has been so easy to do so little about climate change since 1938. Later this year, the Intergovernmental Panel on Climate Change will make some highly equivocal, backtracking announcements. In a report due for release in December, the IPCC will concede that we can’t be sure tropical cyclones will become more frequent, or that droughts will get worse. Worries that the Gulf Stream will collapse, tentatively raised in the 2007 IPCC report, are allayed: such an event is “unlikely” to occur in the foreseeable future.

Concern over details can have an unhelpful effect, masking the big picture on climate change – the one that Nicholas Stern, who wrote the UK government’s 2006 review on the science, said at Davos last month is “far, far worse” than we were led to believe originally. Until that, rather than the detail, becomes the focus, we can continue to dither over whether to do anything, let alone deciding what course we might take.

It does not matter a great deal that no one is willing to risk his career by backing Luca Turin – but to wait for absolute certainty over the details of climate change before we do anything about it will spell life or death for many. If science continues to advance one funeral at a time, its acceleration is assured; and there will be no shortage of funerals in a world that’s 4° warmer.

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 11 February 2013 issue of the New Statesman, Assange Alone

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Space suicide: the sad but noble death of the Cassini probe

It’s not surprising that scientists and space geeks around the world will bid it adieu with a heavy heart.

Since April 2016, a Twitter bot called @CassiniNoooo has been tweeting out “Nooooo” followed by random numbers of “O”s. The last tweet sent by the bot is just “I......”.  

The account has been paying a light-hearted tribute to one of the most important important scientific projects of recent times, and one which is soon to come to an end. 

Launched in 1997, Cassini-Huygens is a plutonium-powered probe that has been circling Saturn since 2004. Providing teams of scientists with unparalleled images of Saturn and its moons, it has allowed experts to examine the composition of solar bodies one billion miles away.

But on 15 September, Cassini will begin its final mission, referred to by Nasa scientists as its "Grand Finale". It will shed its modules and sensors as it heads towards a final fiery death in Saturn's gaseous atmosphere.

When news of Cassini's impending end was announced in April, scientists, casual space fans, engineers, teachers and other assorted stargazers expressed sadness about the craft’s suicide mission. Many are expected to tune in to watch the live stream of the probe's final moments on Nasa’s dedicated webpage

Cassini has provided some of the most intriguing discoveries about our solar system. It discovered a saltwater ocean under the icy surface of one of Saturn’s moons, Enceladus, by "tasting" molecules – a finding that could, in theory, support alien life. It also took photographs of Titan, a moon bigger than Mercury, which enabled scientists on earth to discover liquid on its surface – only the second body in the universe to have free-standing liquid after our own planet. 

In a way, Cassini's discoveries signed its own death warrant. Potentially life-supporting pristine environments must not be contaminated by Earth-originating microbes and, left to its own devices, Cassini could collide with one of the moons it discovered so much about.

Faithful until its last moment, Cassini will be diving in and out of the space between Saturn and its rings as it reaches the end of its final orbit, a feat never achieved before, transmitting completely novel data that would be too risky to gather unless it was already destined for immolation.

Cassini's contribution to science, laid out in this oddly moving webpage from Nasa, not only allowed us a deeper understanding of our solar system, but also helped us picture other kinds of worlds. It's a service that has been recognised well beyond academics or professional scientists. One six-year-old is even throwing Cassini a goodbye party, with a themed cake and games – because, he said, it was the “only spacecraft he ever knew”. Others have tweeted out music composed for Cassini, and comics depicting their versions of its final moments.

It has not been easy for the scientists who had to approve the decision to kill Cassini. In a press conference on 4 April, roughly three weeks before Cassini started its final orbit, Linda Spilker, a planetary scientist at Nasa's Jet Propulsion Laboratory, admitted that it was hard to say goodbye to their “plucky, capable little spacecraft”. Some even referred the probe as their child.

On Earth, we get to think of these robotic explorers like astro-ambassadors, not least because so much of the current discussion around space monitoring centres on how information collected will enable life in space for humans. Now one of those ambassadors is about to make its final visit to a foreign planet, long before its creators will get to make their own introductions.