Saturday, November 07, 2015

Vacuum fluctuations, modelling in systems biology, and overconfidence in economics

Fig 3 of Riek at al.  A: sketch showing lateral increase in
sampling cross section which leads to averaging over
noise patterns in circled areas. B: differential histograms
at various positions of the beam detector.
Three papers from Science catch my attention:
  • A fascinating paper by Riek at al called "Direct sampling of electric-field vacuum fluctuations" demonstrates direct detection of the vacuum fluctuations of electromagnetic radiation in free space by using tightly focused laser pulses lasting a few femtoseconds. This allows "an extreme time-domain approach to quantum physics, with nondestructive access to the quantum state of light. Operating at multiterahertz frequencies, such techniques might also allow time-resolved studies of intrinsic fluctuations of elementary excitations in condensed matter." The paper derives a theoretical 4.7% change in the total normalised noise bandwidth and then shows a 4% widening experimentally.  This is really exciting stuff - though once again I'd have liked to see a lot more data so that the uncertainly could be narrowed. Probably there is no significant difference between 4% and 4.7% but it would be very interesting if there were.
  • My friend Michael Stumpf and his colleagues have an nice comment paper on Systems Biology whose conclusions are well worth quoting Models are simplified (but not simplistic) representations of real systems, and this is precisely the property that makes them attractive to explore the consequences of our assumptions, and to identify where we lack understanding of the principles governing a biological system. Models are tools to uncover mechanisms that cannot be directly observed, akin to microscopes or nuclear magnetic resonance machines. Used and interpreted appropriately, with due attention paid to inherent uncertainties, the mathematical and computational modelling of biological systems allows the exploration of hypotheses. But the relevance of these models depends on the ability to assess, communicate, and, ultimately, understand their uncertainties.
  • In their remarkable "Peer effects on worker output in the laboratory generalize to the field" Daniel Herbst and Alexandre Mas compare peer effects on productivity (workers become more productive is their co-workers are more productive) from lab and field studies. By conducting a meta-analysis of published lab and fields studies they find that the relevant parameter is 0.15 (0.04, 0.26) in the lab and 0.11 (0.03,0.18) in the field, which suggests that there is probably one consistent value 0.12 (0.06,0.18) (the figures in brackets are 95% confidence limits). But what I find almost equally fascinating is that, as you can see from their Fig 1 below this lies outside the published "95% confidence limits" of 18% (2/11) of the lab studies and 48% (11/23) of the field studies.  Moral: these studies may be "accurate" but they are vastly overconfident.
Fig 1 from Herbst and Mas


Steve Finnell said...


How is it possible for those who claim to be Christians to deny the Genesis 1 account of a 24 hour day, six day creation?

The apostle Paul tells us that all Scripture is given by inspiration of God, (2 Timothy 3:16).

How can men believe that God had the power to raised Jesus from the dead, however, God could not create the heavens and earth in six 24 hour days. (Note: God is not bound by time, He created time. SEE: Genesis 1)

Was the Genesis account of creation not inspired by God? The entire Bible is God's word, not just the parts we choose to believe.

You can believe all of the Bible or reject all of the Bible. Men are not free to chose the Scriptures that fit their personal or denominational view.


starcourse said...

Scripture makes it abundantly clear that God's view of time is not the human view. And it's very clear that not all the details of the two creation accounts in Genesis are to be taken literally: some of them conflict quite deliberately.

There is also nothing about "24 hour days" in Genesis.