Nikola Poljak, Dora Klindzic, Mateo Kruljac
At some point in the future, if mankind hopes to settle planets outside the Solar System, it will be crucial to determine the range of planetary conditions under which human beings could survive and function. In this article, we apply physical considerations to future exoplanetary biology to determine the limitations which gravity imposes on several systems governing the human body. Initially, we examine the ultimate limits at which the human skeleton breaks and muscles become unable to lift the body from the ground. We also produce a new model for the energetic expenditure of walking, by modelling the leg as an inverted pendulum. Both approaches conclude that, with rigorous training, humans could perform normal locomotion at gravity no higher than 4 gEarth.
Read more at https://arxiv.org/pdf/1808.07417.pdf
Perhaps the questions were too speculative for his time, but Charles Darwin never considered whether another evolutionary experiment exists in the universe or what such an experiment might look like. Once life emerged on Earth, it proliferated across the planet, assumed remarkable forms, and wrought the extraordinary changes that have now inextricably linked the biosphere and geosphere. The oxygen that you and I breathe originated as the result of photosynthetic activity so pervasive and so productive that it eventually reached levels sufficient to drive a complex multicellular biosphere…
Read more at http://physicstoday.scitation.org/doi/10.1063/PT.3.3493
How much is your time really worth? Student paper evaluates the economics of thought
Big thinkers may wish to re-evaluate their rates, according to a student study at the University of Leicester, which tested the popular idiom ‘A penny for your thoughts’ by working out how much of a person’s thought could theoretically be purchased with a single penny.
The study suggests that a penny could, in theory, purchase 3 hours, 7 minutes and 30 seconds of thought according to Natural Sciences student Osarenkhoe Uwuigbe from the University of Leicester’s Centre for Interdisciplinary Science.
In a paper published in the Journal of Interdisciplinary Science Topics, a peer-reviewed student journal run by the University of Leicester’s Centre for Interdisciplinary Science, the student first investigated how much power is needed to produce thought.
For simplicity, the study examined the power necessary for the brain – which consumes roughly 20 per cent of the body’s energy – to run as being the power necessary for the production of thought.
Given that the average power consumption of a typical adult is approximately 100 watts, the student calculated that the power necessary to run a human brain and produce thought is roughly 20 per cent of this – or 20 watts.
To apply monetary value to thought, the price per kilowatt hour (kWh) charged by UK energy companies was calculated, settling on 16 pence per kWh, which is within the range of prices typically charged by UK energy companies.
Assuming that it requires 20 W or 1/50 kW to produce thought, charging 16p per kWh means that one penny can purchase 1/16th of a kWh. Therefore the length of time (in hours) a penny can purchase thought for is (1/16)÷(1/50)=3.125.
Assuming that it is possible to think as fast as you can speak, the student suggests that 3 hours, 7 minutes and 30 seconds of thought and speech can be bought with a penny.
Student Osarenkhoe Uwuigbe said: “This model is likely to be an underestimate as power required for the brain to operate does not necessarily translate to power used in thought. The brain has several autonomic functions it carries out during thought processing and as a result thought processing could not take 100% of the power consumption of the brain.
“Furthermore, it is unlikely that it is possible to think as fast as you speak due to delay caused by biological constrains such as conduction velocity of nerves carrying the signal from the brain to the mouth, the release of Ca2+ ions during muscle contraction of the tongue and lips and so on.”
Dr Cheryl Hurkett from the University of Leicester’s Centre for Interdisciplinary Science said: “An important part of being a professional scientist (as well as many other professions) is the ability to make connections between the vast quantity of information students have at their command, and being able to utilise the knowledge and techniques they have previously mastered in a new or novel context.
“The Interdisciplinary Research Journal module models this process, and gives students an opportunity to practise this way of thinking. The intention of this module is to allow students to experience what it’s like to be at the cutting edge of scientific research.
“The course is engaging to students and the publishing process provides them with an invaluable insight into academic publishing. It also helps students feel more confident when submitting future papers. I find it a very rewarding module to teach and I am always pleased to see my students engaging so enthusiastically with the subject. I encourage them to be as creative as possible with their subject choices as long as they can back it up with hard scientific facts, theories and calculations!”
The self-organization properties of DNA-like molecular fragments four billion years ago may have guided their own growth into repeating chemical chains long enough to act as a basis for primitive life, says a new study by the University of Colorado Boulder and the University of Milan.
While studies of ancient mineral formations contain evidence for the evolution of bacteria from 3.5 to 3.8 billion years ago — just half a billion years after the stabilization of Earth’s crust — what might have preceded the formation of such unicellular organisms is still a mystery. The new findings suggest a novel scenario for the non-biological origins of nucleic acids, which are the building blocks of living organisms, said CU-Boulder physics Professor Noel Clark, a study co-author. Continue reading New study hints at spontaneous appearance of primordial DNA