Category Archives: Science

there is no climate emergency – letter

With Global Warming protests and strikes held by student in a number of countries, a group of 500 scientists and other “professionals in climate and related fields” have written an open letter to the United Nations . In the letter, the signatories state that “climate science should be less political, while climate policies should be more scientific,” while also denouncing “the uncertainties and exaggerations in…predictions of global warming.” The text is reproduced below and the full letter available for download.

A polar bear in Repulse Bay, Nunavut Territory, Canada.
Paul Souders | Getty Images

There is no climate emergency

A global network of 500 scientists and professionals has prepared this urgent message. Climate science should be less political, while climate policies should be more scientific. Scientists should openly address the uncertainties and exaggerations in their predictions of global warming, while politicians should dispassionately count the real benefits as well as the imagined costs of adaptation to global warming, and the real costs as well as the imagined benefits of mitigation.

Natural as well as anthropogenic factors cause warming

The geological archive reveals that Earth’s climate has varied as long as the planet has existed, with natural cold and warm phases. The Little Ice Age ended as recently as 1850. Therefore, it is no surprise that we now are experiencing a period of warming.

Warming is far slower than predicted

The world has warmed at less than half the originally-predicted rate, and at less than half the rate to be expected on the basis of net anthropogenic forcing and radiative imbalance. It tells us that we are far from understanding climate change.

Climate policy relies on inadequate models

Climate models have many shortcomings and are not remotely plausible as policy tools. Moreover, they most likely exaggerate the effect of greenhouse gases such as CO2. In addition, they ignore the fact that enriching the atmosphere with CO2 is beneficial.

CO2 is plant food, the basis of all life on Earth

CO2 is not a pollutant. It is essential to all life on Earth. Photosynthesis is a blessing. More CO2 is beneficial for nature, greening the Earth: additional CO2 in the air has promoted growth in global plant biomass. It is also good for agriculture, increasing the yields of crops worldwide.

Global warming has not increased natural disasters

There is no statistical evidence that global warming is intensifying hurricanes, floods, droughts and suchlike natural disasters, or making them more frequent. However, CO2-mitigation measures are as damaging as they are costly. For instance, wind turbines kill birds and bats, and palm-oil plantations destroy the biodiversity of the rainforests.

Climate policy must respect scientific and economic realities

There is no climate emergency. Therefore, there is no cause for panic and alarm. We strongly oppose the harmful and unrealistic net-zero CO2 policy proposed for 2050. If better approaches emerge, we will have ample time to reflect and adapt. The aim of international policy should be to provide reliable and affordable energy at all times, and throughout the world.


Galactic Colonization: A New Model

2D slice of 3D simulation of expansion of the Galactic Settlement front. Blue is unsettled, red is settled and green is targeted

Jonathan Carroll-Nellenback and partners have published a fine article in Astrophysical Journal on a modelling exercise on civilizational expansion across the Milky Way, addressing the Fermi Paradox. According to a study published last month in The Astronomical Journal, extraterrestrial life might be taking its time to fully explore the galaxy, even using the movement of star systems to make this type of journey easier.

The Fermi Paradox has a long history in discussions of the prevalence of “alien” technological civilizations (i.e. ‘exo-civilizations’) in the galaxy. Originating with a lunchtime conversation in 1950 where Enrico Fermi famously asked ‘where is ev­erybody?’, the Fermi paradox was first for­malized in 1975 and has since become a standard framework for addressing questions concerning the preva­lence of exo-civilizations. Formally the paradox might be expressed as follows: “If technologically advanced exo-
civilizations are common, then we should already have evidence of their existence either through direct or in­direct means”

Assuming amongst other things that any interstellar probe would have a minimum velocity of 30km/sec which would be achievable using gravity assist from large planets within 1 AU they reach a number of interesting conclusion:

  • When diffusive stellar motions are accounted for, they contribute to the Galaxy becoming fully set­tled in a time less than, or at very least comparable to its present age, even for slow or infrequent in­terstellar probes;
  • If a settlement front forms, all settleable systems behind it become “filled in” in a time less than the current age of the Galaxy;
  • While settlement wave crossing and fill-in times are short, consideration of finite civilization lifetimes in a steady state model allows for conditions in which the settled fraction is less than 1. Thus the galaxy may be in a steady state in which not every settleable system is currently settled.
  • Statistical fluctuations in local density of settleable systems allows for the formation of set­tlement clusters which can continually resettle one another. These clusters are then surrounded by large unsettled regions. If such conditions repre­sent the situation in our region of the galaxy and Earth was not in one of the ”re-settlement” clusters it would be highly probable that we would not have been settled (or visited) by another civilization for some time.
  • By consideration of the convolution of steady state solutions with geologic evidence horizons, it is pos­sible to find situations in which Earth may not have experienced a settlement event for longer than some horizon time (assumed to be 1 Myr) even though the galaxy supports a population of inter­stellar civilizations.

Even for slow probes (30 km/sec) they find that the upper limit of the galactic crossing times are just less than 1 Gyr. This is in accord with our modelling for the colonization of the Type A stars within 100 LY of Earth assuming 5 habitable planets amongst the 75 stars that meet this criteria. We estimated that dependent on probe speed would take between 350,000 and 900,000 years.

The authors discuss amongst other things the energy requirements for interstellar travel and suggest that this is a major impediment to the postulated wave of colonization. A multi-generational ship would they suggest require economies equivalent to that of entire solar systems. They consider a ‘medium multi-generational cruiser’ case . This would be a ship traveling at v = 0.05c, carrying a population of 104 people and weighing 107 tonnes. Such a ship would require a power of 6900 zettajoules (ZJ) funded by a solar sys­tem wide civilization of 900 billion people that would generate 1136 ZJ per year. The world presently produces around 1 ZJ Joule and this quantum of energy would require a significant civilizational commitment.

Download the Full Text

The Fermi Paradox and the Aurora Effect: Exo-civilization Settlement, Expansion and Steady States

Jonathan Carroll-NellenbackAdam FrankJason WrightCaleb Scharf(Submitted on 12 Feb 2019)

We model the settlement of the galaxy by space-faring civilizations in order to address issues related to the Fermi Paradox. We explore the problem in a way that avoids assumptions about the intent and motivation of any exo-civilization seeking to settle other planetary systems. We first consider the speed of an advancing settlement via probes of finite velocity and range to determine if the galaxy can become inhabited with space-faring civilizations on timescales shorter than its age. We also include the effect of stellar motions on the long term behavior of the settlement front which adds a diffusive component to its advance. The results of these models demonstrate that the Milky Way can be readily ‘filled-in’ with settled stellar systems under conservative assumptions about interstellar spacecraft velocities and launch rates. We then consider the question of the galactic steady-state achieved in terms of the fraction of settled planets. We do this by considering the effect of finite settlement civilization lifetimes on the steady states. We find a range of parameters for which the galaxy supports a population of interstellar space-faring civilizations even though some settleable systems are uninhabited. Both results point to ways in which Earth might remain unvisited in the midst of an inhabited galaxy. Finally we consider how our results can be combined with the finite horizon for evidence of previous settlements in Earth’s geologic record. Our steady-state model can constrain the probabilities for an Earth visit by a settling civilization before a given time horizon. These results break the link between Hart’s famous “Fact A” (no interstellar visitors on Earth now) and the conclusion that humans must, therefore, be the only technological civilization in the galaxy.

Arc/Info Binary Grid import

I have had occasional issues with the import of Arc/Info Binary Grid format files into ARCGIS. The solution is all too easy. The import script is legacy and relies on the oldest of ARCGIS file and directory formatting requirements, no spaces. No spaces in parent directories or file names. The naming convention in ARCGIS is really quite annoying at times.

At the Moment of Creation there was the Fluid

An event from the first Xenon-Xenon collision at the Large Hadron Collider at the top energy of the Large Hadron Collider (5.44 TeV ) registered by ALICE [credit: ALICE]. Every colored track (The blue lines) corresponds to the trajectory of a charged particle produced in a single collision; [right] formation of anisotropic flow in relativistic heavy-ion collisions due to the geometry of the hot and dense overlap zone (shown in red color).
Scientists from the Niels Bohr Institute, University of Copenhagen, and their colleagues from the international ALICE collaboration recently collided Xenon nuclei, in order to gain new insights into the properties of the Quark-Gluon Plasma (the QGP) – the matter that the universe consisted of up to a microsecond after the Big Bang.

The QGP, as the name suggests, is a special state consisting of the fundamental particles, the quarks, and the particles that bind the quarks together, the gluons. The result was obtained using the ALICE experiment at the 27 km long superconducting Large Hadron Collider (LHC) at CERN. The result is now published in Physics Letters 

With collisions approaching the speed of light and enormous energy (5.44 TeV) a fireball lasting a mere 10-22 seconds was generated at temperatures of several thousand billion degrees.

Under these conditions a plasma of hadron components is created consisting of quarks and gluons.  the density of the plasma is very high and forms a special state of matter known as the strongly interacting QGP.

The experiments suggest that the primordial matter, the instant before atoms formed, behaves like a liquid that can be described in terms of hydrodynamics.

The experiments involved  studying the spatial distribution of the many thousands of particles that emerge from the collisions when the quarks and gluons have been trapped into the particles that the Universe consists of today. This reflects not only the initial geometry of the collision, but is sensitive to the properties of the QGP.

The Alice Detector at the Large Hadron Collider

Source: Neils Bohr Institute

Anisotropic flow in Xe–Xe collisions at 5.44  TeV


The first measurements of anisotropic flow coefficients vn for mid-rapidity charged particles in Xe–Xe collisions at sNN=5.44 TeV are presented. Comparing these measurements to those from Pb–Pb collisions at sNN=5.02 TeV, v2 is found to be suppressed for mid-central collisions at the same centrality, and enhanced for central collisions. The values of v3are generally larger in Xe–Xe than in Pb–Pb at a given centrality. These observations are consistent with expectations from hydrodynamic predictions. When both v2 and v3 are divided by their corresponding eccentricities for a variety of initial state models, they generally scale with transverse density when comparing Xe–Xe and Pb–Pb, with some deviations observed in central Xe–Xe and Pb–Pb collisions. These results assist in placing strong constraints on both the initial state geometry and medium response for relativistic heavy-ion collisions.

Full Text

This could be the most advanced entity in the universe

A riveting video from David Kipping at Astronomy Columbia.  Is there life out there?  We simply have no idea as it’s not possible to extrapolate from a  single data point –  Earth.  It could well be that the creation of life is very difficult and we are the only example of life in our galaxy or indeed in the entire observable universe.  We simply have no data to suggest otherwise.  It would explain the absence of evidence of life in the radio spectrum and we have been looking for 50 years.  The prospect that we are the only sentient beings within the observable universe (~30 billion light years across is both wonderful and rather terrifying.

That said it is interesting to contemplate that we and our animal relatives are likely the most complex entities on this planet and in this solar system.  Given that we have seen no evidence of other sentient beings in the radio spectrum in the last 50 years or so it might also be reasonable to suggest that we are likely the most complex entities with hundreds of light years of Earth.  It would however be nice if life were present in profusion elsewhere –  but we simply do not know.

It might well be that it is us who are the “Aliens” and that over the next few hundred million years we will populate a vast region of this corner of our galaxy.  I find this somehow very satisfying.

A Big 5 analysis of Steve Jobs

Steve Jobs was and remains a most enigmatic individual, driven by product excellence, focused  to an obsessive degree but with little empathy for those around him.  Below is a is an interesting paper on Jobs, by Bert McBrayer, within the framework of the Big 5 Personality traits.  Bert concludes that history will likely paint Jobs as an innovator but likely not include him in the pantheon of leaders of people.


My take on Steve Jobs

Openness:  Above average aspect Intellect but off the scale aspect Openness.  Likely out of 100 people he would be more open to experience than the 99 other people in the room.

Conscientiousness: Off the scale aspect Industriousness but low in aspect Organization.  What make Jobs unusual is the focus of his Industriousness.

Extraversion:  Off the scale for both aspects Enthusiasm and Assertiveness

Agreeableness:  Very low aspect Empathy and Politeness but could modify both if this furthered his product goals

Neuroticism:  A reliable indicator of suitability for management is a low-level of Neuroticism or reaction and response to negative events.  Jobs was legendary for his volatility but appears to have had low levels of withdrawal.

What appears to have made Jobs unique was his remarkable Industriousness and focus, combined with the creativity commensurate with above average intellect and exceedingly high openness.  He used with pleasure his high Aspect Volatility in combination with his low Trait Agreeableness bound into a laser like product focus to stimulate his team.  Steve was product and not people focused and may have retreated from the “scar tissue” of his rejection as an infant into the infinite detail of product design and artistic endeavour.

Ossiris-REx begins preliminary survey phase ahead of orbital insertion

NASA’s OSIRIS-REx spacecraft after a 2 billion km journey, has reached and is now in orbit around asteroid Bennu.   See previous post.

Below is a series of images taken by OSIRIS-REx at a distance of about 80 km (50 mi.) The images constitute one full revolution of the asteroid.

The spacecraft is now in the Preliminary Survey Phase which began on December 3, 2018, and marks the first time that the OSIRIS-REx spacecraft will operate around the asteroid. The spacecraft will make a total of five passes over the north pole, equator, and south pole at a range of 4.3 miles (7 km). The primary science goals of Preliminary Survey are to estimate Bennu’s mass, refine the asteroid’s spin state model, and generate a global shape model at a resolution of 75-cm.  With this information orbital insertion can be planned and detailed (and close) survey of the asteroid can begin.


Our Star’s sibling – looks like a good candidate

Its 4.5 billion years since our solar system formed in a  gaseous nebula.  These nebula formed from the explosive collapse of stars, larger than Sol, when they have exhausted much of their hydrogen.  These Supernova cast much of their mass into space forming  a gaseous nebula.  These nebula are however large –  much larger than our solar system and are incubators of star formation, sometimes hundreds of stars, much like the glowing nebula in the image below.

NASA, ESA, and the Hubble SM4 ERO Team –
Composed of gas and dust, the pictured pillar resides in a tempestuous stellar nursery called the Carina Nebula, located 7500 light-years away in the southern constellation of Carina. Taken in visible light, the image shows the tip of the three-light-year-long pillar, bathed in the glow of light from hot, massive stars off the top of the image. Scorching radiation and fast winds (streams of charged particles) from these stars are sculpting the pillar and causing new stars to form within it. Streamers of gas and dust can be seen flowing off the top of the structure. Hubble’s Wide Field Camera 3 observed the Carina Nebula on 24-30 July 2009. The composite image was made from filters that isolate emission from iron, magnesium, oxygen, hydrogen and sulphur.

Overtime, the varied gravitational environment in the galaxy results in stars formed from the same nebula drifting apart, however they will retain the same composition and have similar spectral characteristics and maybe even be of comparable in size.  Finding these siblings would require a massive star survey.  We would have to know the distance from Earth, the relative speed and direction and the composition.  Given that there are a vast number of stars in our immediate neighborhood –  this is a daunting task.

The Gaia spacecraft is performing just such a  survey of the Milky Way.  Gaia is measuring the distance, velocity and spectral characteristics for a billion stars in our galaxy has now spotted what appears to be a twin (HD186302) of Sol and it has near identical spectral characteristics.  Of the 200,000 stars in the spectral Gaia catalog only one star, HD186302, has near-identical chemistry to Sol.

HD186302 is a G3-Type main sequence star with about same surface temperature as Sol and is about the same age, 4.5 BY.  HD186302 is located 184 light years from Earth,   which sounds like it’s very distant.  However, to achieve this separation if Sol and HB186302 were original 1-2 light-years apart within the nebula it would only require a relative velocity between Sol and HD186302 of 65,000 km/hr since formation to have achieved the current separation.  In galactic terms this is a very realistic relative speed.