Category: Science

New discoveries, the scientific method, and all matters relating to the scientific study of the physical world

Cancer and the neutron

I think of cancer, and radiation therapy for it, as modern phenomena. It was surprising, then, to learn that radon ‘seeds’ were being used for radiation therapy of cancer in 1929 – before the neutron had even been discovered. Indeed, polonium extracted from depleted seeds from Baltimore’s Kelly Hospital provided James Chadwick with the neutron source for the experiment that confirmed their existence. Neutrons are critical for inducing the fission of atoms, whether in bombs or power plants, because they are not repelled by the electric fields around atoms.

A detailed account of the experiment is in chapter 6 of Richard Rhodes’ The Making of the Atomic Bomb.

Sea ice extent and volume

Over at RealClimate, Dirk Notz has written a good post about climate change and Arctic sea ice. In it, he highlights the importance of aggregated data, pointing out how, despite variations in regional weather, the mean temperature of the entire globe during the last 12 months is the highest it has been since the beginning of the records 130 years ago.

The figure that is most watched, when it comes to Arctic sea ice, is the extent of ocean covered by ice. This isn’t a spectacularly good measure, however, as Notz explains:

The reason for this is mostly that sea ice in the Arctic has become very thin. Hence, in contrast to the much thicker ice of past decades, the ice now reacts very quickly and very sensitively to the weather patterns that are predominant during a certain summer. This currently limits the predictability of sea-ice extent significantly.

A better measure is ice volume, which has been falling consistently as the planet warms.

Ten indicators from the Met Office

One reason we can have a lot of confidence about the basic science of climate change – that the world is warming, because of people, in ways that could be harmful to humanity – is because there are numerous independent indicators showing the same trends. A new report from the Met Office in the United Kingdom highlights this, pointing to ten distinct indicators that all show the planet warming:

  1. Rising air temperature over land
  2. Rising sea-surface temperature
  3. Rising marine air temperature
  4. Rising sea-level
  5. Rising ocean heat
  6. Rising humidity
  7. Rising tropospheric temperature in the ‘active-weather’ layer of the atmosphere closest to the Earth’s surface
  8. Declining arctic sea-ice
  9. Declining glaciers
  10. Declining spring snow cover in the northern hemisphere

Deke Arndt, who co-edited the report, explained that: “The records come from many institutions worldwide. They use data collected from diverse sources, including satellites, weather balloons, weather stations, ships, buoys, and field surveys. These independently produced lines of evidence all point to the same conclusion: our planet is warming.”

None of this is new, really, but there is value in re-expressing it and stressing how the different indicators reinforce one another. Climate change deniers often fixate on details, raising doubts about a single measure and then suggesting that this calls into question the whole edifice of climate science. What work like this Met Office report indicates is how climate scientists are approaching the problem in a way that reduces the danger of such dangerous extrapolations.

Of course, that means climate change is something we really do need to worry about, and which we ought to be taking much more action about.

The DSM and defining mental illness

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is published by the American Psychiatric Association and contains the most authoritative definitions of mental illnesses. The current version – the DSM-IV – was released in 1994. Now, work is ongoing on a fifth edition.

To me, it seems like ‘mental illness’ often describes a situation in which a person manifests a normal part of psychology to an excessive extent. For instance, it is perfectly normal and probably even essential for people to feel things like guilt, shame, and anxiety. Any of these felt to an extreme extent, whether that means extremely strongly or weakly, could form the basis for a mental illness.

There is a danger, perhaps, in being too quick to say that someone is ill, when they simply manifest a normal tendency to an unusual degree. Doing so might make them feel stigmatize and lead to unnecessary medical interventions. It also risks making people feel less responsible for their choices and actins, since they can be ascribed to a medical condition rather than to the free expression of their will. At the same time, increased awareness of mental illness is probably an important thing for society to develop. My sense is that most people do not have a great understanding of the character of mental illnesses, and that society is generally poorly set up to assist people suffering from them.

Materialism and free will

I have written before about the apparent contradiction between free will and materialism (the idea that the universe is exclusively comprised of particles that obey physical laws). The problem is easy enough to state: if every particle in the universe behaves in a manner governed by a combination of random chance and predictable laws, how can a physical entity like the brain respond to stimuli in a way that is neither random nor determined?

Joshua Gold of the University of Pennsylvania and Michael Shadlen of the University of Washington recently summarized some experiments on monkeys that illuminate this issue. They found that they could use a computer to predict how monkeys will respond to visual stimuli, suggesting that such mental functions are automatic.

Of course, there is a big difference between parts of mental life like maintaining a steady heartbeat and tracking a moving object visually and those like making ethical decisions. That said, I continue to be unable to see what mechanism could exist between the former and the latter, and which could square our intuitive belief in free will with what we know about the functioning of the universe. That being said, we do not have any reason to act as though free will does not exist. The reason for that is simple: if free will doesn’t exist, we don’t have any influence over what we believe or how we act, while if it does exist we certainly want to behave appropriately. As such, if we do have any scope to choose, we should choose to believe in free will.

Better two-stroke engines

Apparently, it might be possible to make efficient two-stroke engines that are less polluting than their predecessors.

Improving the efficiency of gasoline and diesel engines is an important undertaking, both because it will be a while before electric vehicles are ready for near-universal urban deployment and because there will be rural vehicles running on fossil fuels for quite a while yet.

How to shift the US Congress?

Writing for Grist, Randy Rieland has come up with a summary of arguments about why cap-and-trade is dead in the United States for now. He is right to say that the blame lies primarily with Congress, rather than with the Obama administration. Congress is the most powerful branch of government, and has been highly effective at blocking environmental legislation in the past. While the Democratic leadership in Congress is theoretically allied with the administration in the White House, even the two together clearly haven’t been able to overcome the wall of opposition to meaningful climate policies that has been constructed by Republicans, or the cowardice of moderate Democrats who are unwilling to fight to address this key problem.

The stragic question now becomes how to change Congressional behaviour, and do so before climate-related disasters become so frequent as to finally discredit climate change deniers completely. We cannot afford to wait that long, both because of the physical lags in the Earth’s climate system and the lags in our own infrastructure deployment. By the time the full danger of climate change is unambiguously on display, it will be too late to avoid some terrible effects. It will also be too late for the relatively unintrusive policies being proposed today to work. Sterner stuff will be required.

David Mitchell on climate change

A couple of years ago, the issue of the consequences of climate change being very depressing came up here, given how dealing with the problem means giving up some excellent things, like being able to visit China or Hawaii on a whim and being able to concentrate our scientific efforts on neat things like space travel.

More recently, David Mitchell (of Mitchell and Webb) produced a funny video with a similar message:

David discusses why tackling climate change is always presented to us by people who either tell us off or patronisingly try to convince us that tackling it is “cool” or “fun”, when actually it’s just something we have to do, because of facts.

I don’t entirely agree with him – since I do see moving to renewable forms of energy as an opportunity. That said, I do like the delivery of his message.