Radioactivity half-life is not a constant

Radioactivity is defined as the spontaneous disintegration of certain atomic nuclei (e.g. carbon-14) into more stable forms (e.g. nitrogen-14). Radioactivity half-life is a measure of how quickly this disintegration occurs, but not for an individual atom.

 It is only measurable and meaningful when considering a large number of radioactive atoms. Then one can talk about how long it takes for half the atoms to decay (i.e. for their nuclei to disintegrate); but looking at one single atom it is absolutely impossible to know whether its nucleus will have decayed in 1 second or 1000 years. One can only talk about the most probable lifetime.

For instance, radium 226 decays into polonium, lead, bismuth and other elements with a half-life of 1601 years. Carbon-14 decays into nitrogen with a half-life of 5,740 years. Yet these figures say nothing about any one atom of Ra-226 or C-14. They are statistical in nature.

Until recently it was assumed that the half-life of samples of elements were constants of nature. Nothing could change them. They reflected the quantum phenomena that go on inside the nucleus of an atom.

It is now looking as though this 80 year old assumption is wrong. There is growing evidence that the radioactivity half life varies with processes occurring inside the sun and the position of the earth in its orbit. This has been found independently in at least three different labs:

 Purdue University, Indiana (manganese-54)

 Brookhaven National Laboratory, NY State (silicon-32)
 German national metrology Institute, Braunschweig (radon-226).

The solar effects are very small – typically 0.1% .Also, they are confined to decay by beta-ray emission - no such effect is observed for decay by alpha- or gamma-ray emission. But they are definitely synchronised to the time when the earth is closest to and furthest from the sun’s northern hemisphere, which is February and August. The radioactive decay rate is higher in February and lower in August than at other times of the year. There is also a correlation with solar flares which could be the basis of a means of forecasting them.

Experiments need to be carried out on carbon-14 because this is used extensively in radiocarbon dating. Variations of a fraction of a percent would not seriously affect existing carbon dating data on archaeological or palaeontological samples. Yet we know that the sun’s activity has not been constant. It is thought to be 20 – 25 % more active now than at the time of the earth’s formation. If miniscule variations in solar activity affect radioactivity very slightly, what would be the effect of large variations? Perhaps none. But if not, the implications for history could be enormous.

Even the small effects discovered to date are inexplicable in terms of existing elementary particle physics. E.g. a new kind of neutrino, the neutrello, has been proposed to explain them but there is no evidence that such a particle exists. It may even be necessary to hypothesise a fifth force in addition to the four already known: electromagnetic, weak nuclear, strong nuclear and gravitational.

Another case of interesting times ahead for physics and possibly for history.

John

Author 2077 AD

See, for example,

proton size puzzle

 http://phys.org/news202456660.html

http://www.sciencenews.org/view/feature/id/38341/title/Half-life_(more_or_less)

http://news.stanford.edu/news/2010/august/sun-082310.html

http://arxiv.org/pdf/1207.5783.pdf

3D printing of houses

 As floods, hurricanes, earthquakes and volcanoes destroy or damage urban areas with growing frequency large numbers of people will need to be rehoused. The proportion of people living in towns and cities is expected to keep growing – it is already over 50% - and many of these extreme natural events occur in or near them because they tend to be built close to

•   Coastlines and rivers – to enable transport by ships

 

•  Tectonic fault lines – because mineral wealth is concentrated in such places

How do you rehouse the population of a large shanty town flooded as the sea level rises? How do you rebuild a large part of a modern city demolished by an earthquake?

 

It is too late to undo the damage done by man already, in the sense of accentuated climate change and of shoddy architecture in the wrong places. Millions of people are likely to need rehousing in the coming decades as extreme climate events increase even faster than predicted and as people continue to flock into cities. Providentially, a new kind of building technology is evolving fast and could be ready for serious, in-field use within a decade: 3 dimensional printing of houses.

 

3D house printing is achieved in a manner similar in principle to the 3D printing already being used. For example, aircraft wings can be designed on a computer and printed layer by layer by extruding the appropriate material through a computer controlled nozzle. There is even a widely available 3D printer costing about a $1000 available to consumers, called the Cube.

It enables you to print out real, physical objects instead of symbols on paper. The set-up for constructing a house would require an overhead gantry from which the printing nozzle would be suspended. The movement of this nozzle, and the rate of supply of composite fibre concrete to it, would be controlled by software defining the structure of the house. This special concrete, which retains its shape while still wet, would be deposited layer by layer, gradually building up the walls. At intervals the printing would be paused to allow floors, insulation, wiring, plumbing and drainage pipes to be installed. The whole process should take less than a day. An engineering professor, Behrokh Khoshnevis, at the University of Southern California, is behind this idea. See this news item.

 Apart from helping communities to recover from disaster the 3D printing principle could be used for house building in normal situations. There are large numbers of people living with minimal protection against the elements and deprived of comforts most people reading this have come to expect. There must be some way of combining this method of building with the installation of sewage systems and power grids.

 

Khoshnevis also proposes using 3D printing as a way of building space colonies in advance of the intended inhabitants. I have not looked into this but it could be more cost effective than transporting prefabricated modules if you wanted to build a colony. It would be a matter of transporting one gantry plus the material rather than numerous modules which would have to be skilfully handled and put together. I suspect that the total freight storage space needed to transport the modules would be larger than for the 3D printing system.

 

One potential of present small scale 3D printing is its use as a basis for custom manufacturing units in shops to help regenerate High Streets. It could possibly be combined with skilled craftsmanship to finish off a basic form.

 

This is powerful technology and it is difficult to imagine it not being used in a big way somehow.

John

Author, 2077 AD

Reach me at cosmik.jo@gmail.com

 

Stop paying for bad news

One hears with increasing frequency of some new revelation about an organisation which casts doubt on its integrity and undermines trust in it to the extent that it is no longer able to function properly, either because the people within it no longer trust their colleagues or because society as a whole  no longer trusts the organisation.

 

For example, if a secret service X is devoted to protecting a parliamentary democracy from destruction by terrorists it must operate on a principle of total secrecy and total trust. It cannot possibly perform its role without keeping secret  the way it operates, the information it has obtained about those wishing to destroy society and the specific measures it has in place to infiltrate hostile groups, intercept their communications or destroy their operations. At the same time all the staff and operatives of X must be able to trust one another – in particular, not to divulge secrets.

 

But the society which X is trying to protect is a democracy with a free press. Suppose some journalists become so motivated by the need for career advancement that they actively seek out transgressions of the internal rules or overall objectives of X. A cost is incurred for every divulgence, true or false: enemies of the state learn something about X and its methods, or the employees suffer diminished trust in each other, which reduces the effectiveness of operations.

 

Consider a national medical service Y (e.g. the UK’s National Health Service) financed by taxation. It needs its staff to be devoted to the well being of all its patients and to trust each other. If a doctor or nurse or porter or cleaner or administrator reveals to a journalist some kind of misdemeanour or bad practice, no matter how rare and unrepresentative, the organisation’s culture is affected and the public becomes less willing to sanction the allocation of tax revenue. Moreover, the confidence of patients is undermined, which in itself can undermine medical treatment.

 

A multinational company Z has branches in several countries. A worker in one country airs grievances to a journalist and this causes a widespread belief that all employees are badly treated, which causes many previously satisfied employees to feel aggrieved. Potential customers then boycott products from Z, its profits fall and workers are made redundant and trust between employers and employees is undermined.

 

Whenever the member of any organisation divulges something negative about it there is a human cost over and above the actual problem reported.  And society is in a sense made up of organisations, so that society as a whole can be badly affected by over-reporting of negative news about the organisations within it. The negative effects are particularly marked when problems in one organisation lead to suspicion that similar organisations have the same problem.

Does this mean one should not report a misdemeanour to the press? No. But what I think is wrong is that the person reporting it should be financially rewarded by the media. If the injustice is so important that its divulgence outweighs in importance the negative impact on the organisation and society in general, then it should be reported regardless of any financial incentive. In general, if an incentive is needed it is, I would argue, questionable whether it should be fed to the public as circulation fodder for a newspaper or to boost the ratings of a TV news show.

 

 Ultimately, if it becomes normal for pedlars of bad news to be rewarded it could be that people start inventing it or distorting events within their employing organisation. In this situation readers would not trust the stories of bad practices and the journalists themselves would no longer profit from bad news they had paid for.

 

The job of a journalist is to proactively unearth news and report it in a balanced and fair way, not to offer incentives to deliver it and in so doing damage the society in which he or she operates.

 Journalist should stop paying for bad news. There may be execptions but in general bringing a genuine injustice to the attention of society should be its own reward.

John

Author, the novel 2077 AD (this is being revised and is not currently available).

Reach me at
cosmik.jo@gmail.com