Reviews - The Adstock Science Club
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I hope from time to time to include reviews of events, books, films, radio and TV programs, documentries or for that matter anything else scientifically or technologically relevant and interesting to our Science Club. If any members or non-members would like to submit an article for inclusion please feel free to email me with your copy and I will try where possible to present it here.
Our first review is from one of our members, Mr Robert Deuchar of the book "Reality is not what it seems: the journey to quantum gravity", by Carlo Rovelli. Published in October 2016 in English by Allen Lane. ISBN: 978-0-241-25796-8.
Rovelli is among the hundreds of researchers into quantum gravity, a hypothesis which combines relativity and quantum mechanics and suggests that there is a granular structure at the smallest "Planck" scale. I will not summarise his conclusions here but gravity is of fundamental importance to our perceptions of space and time if quantum gravity is correct. The book is "technical" in places but the reader can skip those bits and also much of the first part of the book, on Greek philosophers and the history of electrodynamics and mechanics, and read what Rovelli thinks our universe is made of at the most basic level. He disapproves of string theory and I'm happy with that! The hypothesis is incomplete and lacks observational evidence. However it seems to me to be our best guess so far. Bravo, Carlo.
Marks out of ten: 9.5.
Should I read it? If interested in physics, yes, definitely.
Robert also gives us a brief outline of what Carlo Rovelli said to interviewer Adam Rutherford on BBC Radio 4's "Inside Science" programme on 13 October 2016.
AR: Carlo Rovelli is a theoretical physicist who wrote "7 Brief lessons in Physics", his latest book just published in English is "Reality is not what it seems". General relativity (GR) says that space is smooth, continuous, while quantum mechanics (QM) says that it is grainy, chunky, like "atoms of space".
CR: Loop quantum gravity (LQG) is hypothetical and proposes that space is like a graph, knit, woven by "threads", these are not moving in space but they are the fabric of space. This is at the Planck scale, much smaller than particle physics. There can be a loop from one point (node) to another and back. He hopes that observations may provide evidence in the effects on the big bang of discreteness, and/or the effects on black holes. In the last few years we have found that the universe is teeming with black holes! What you learned at school may be wrong! With a black hole we know from the outside how they behave and what happens when matter falls in, as far as the event horizon. However we have no idea of the inside and that's where we need LQG, and we have no idea of their fate in the long term. If LQG is right a black hole may have a short life, they can explode! There's no infinite density, that is an error as GR ignores QM. One possibility is that a star collapses to form a black hole and matter falls to the centre but QM stops the compression, it bounces out, it explodes! The magic is the following: in GR times go at different speeds at different altitudes. One millisecond at the centre but one billion years as seen from the outside! Therefore a black hole may be a bouncing star which we see in very slow motion.
AR: In your latest book you say that you are not completely wedded to LQG?
CR: That's how science should work. We should distinguish between things which we know well and things which are open to testing. For example, Plato wrote that he thought that the Earth was a sphere but that he was not sure!
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CR does not say so in the interview but one implication seems to be that the whole universe visible to us may be a white hole, the bounce of a previous collapse. I don't know what he thinks about inflation, whether it is still needed to solve the flatness problem. Maybe LQG space, consisting of the gravitational field, is flat as its default position. Maybe the horizon problem is solved as the collapse would have made the matter homogeneous. In which case you don't seem to need cosmic inflation, which would be a relief as it seems an artificial solution.
Robert Deuchar.
17th October 2016.
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Our next review, has been provided by one of our members Fiona Durham, is for a recent event held at the Open University in Milton Keynes for the Institute of Physics on Tuesday 14th February, 2017 - "Where next after Rosetta? Comets, asteroids, and some confused objects in between" - presented by Dr Colin Snodgrass.
Colin Snodgrass was talking about the background to the Rosetta mission last week which I expect you all know about. He had some amazing images. He then went on to talk about some of their findings including the wide range of compounds such as ammonia, hydrogen cyanide and hydrogen sulphide found on the comet. He had a a stack of smelly postcards which he claimed smelled like the comet! The amino acid glycine was also found. One of the most intriguing discoveries was that 67p has water with a much higher isotopic ratio of deuterium than the Earth's.
They are now hunting for another source for Earth's water and they are turning their attention to the asteroids and the recently discovered main belt comets which have a circular orbit rather than the usual elliptical ones. They are currently trying to get ESA funding for two new missions, the first to the main belt comets to look for this water among other things. http://oro.open.ac.uk/42830/ He is also involved in a second project proposal CASTaway to do a grand tour of the asteroids: https://sites.google.com/site/castawaymission/
Monica Grady posted an article in The Conversation about the discovery of organic molecules on Ceres recently, so it looks as though the asteroid belt is very much in the sights of researchers at the moment!
Fiona Durham
19th February 2017
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Phillip Ball Interviews Roger Penrose about his new book - Fashion, Faith and Fantasy in the New Physics of the Universe
Saturday 25th March at the the Sheldonian Theatre in Oxford.
This is what the website said about it in advance:
"Bestselling author and one of the world’s leading theoretical physicists Professor Sir Roger Penrose argues that fashion, faith and fantasy may be leading some researchers astray on the extreme frontiers of physics. Penrose says fashion, faith and fantasy can sometimes be productive in physics but it is leading today’s researchers astray in three important areas – string theory, quantum mechanics and cosmology. He warns that the fashionable nature of a theory can sometimes cloud our judgment and that success in one application of a theory can lead to uncritical faith in other applications. Penrose says many of the fantastical ideas about the origin of the universe cannot be true. And he goes on to show how fashion, faith and fantasy have ironically shaped his own work including in conformal cyclic cosmology, an idea so fantastic he says it could be called conformal crazy cosmology.
Penrose is Rouse Ball Professor of Mathematics Emeritus at the University of Oxford. He has won many prizes, including the Albert Einstein Medal for his contributions on general relativity and cosmology. He is co-author with Stephen Hawking of The Nature of Space and Time and author of The Road to Reality: A Complete Guide to the Laws of the Universe.
Here he talks to freelance science writer Phillip Ball, author of a number of popular science books, a regular contributor to Nature and presenter of Science Stories on BBC Radio 4."
The interviewer Ball started by asking P about his grandfather and father and I thought that was a bit of a waste of time. Later P spoke about Dirac (quantum mechanics) and Hermann Bondi (relativity) at Cambridge and how he switched from geometric pure maths and topology to applied maths, linked up with Hawking and studied black holes and singularities. Quasars were discovered (around 1963) and so black holes were eventually thought to be the source of such powerful but varying emitters. He described quantum mechanics as deficient in that it did not seem to make sense to have a particle in two places at once,, which Einstein famously queried, and that Schrodinger with his famous cat paradox was drawing attention to the failure of q.m. in this area, not its success! He initially liked string theory but when it had to have 26 dimensions, later 11, he thought that unlikely and not proven to be necessary and also preferred to pursue his personal project: twistors. I don't think he mentioned loop quantum gravity. He said he did where possible address physics problems visually whereas others preferred the mathematical approach and mentioned Feynman diagrams. He did talk about the Schwarzschild solution to black hole geometry, Oppenheimer and that he and H found that in relativity you should get a singularity even if your initial collapsing star is irregular in shape. He said that he gave a lecture about 10 years ago to lots of string theorists and said that he felt that the number of degrees of freedom did not make sense in string theory and afterwards Leonard Susskind said to him that he was right, of course, but misguided! P has been puzzling over this ever since! He did not mention his cyclic "bouncing" cosmology. He did mention his ideas on quantum theory in relation to consciousness and said that a researcher is hoping to test P's ideas experimentally.
There were two questions from the floor, the only one which I remember was "is it possible that there are 3 time dimensions, corresponding to the 3 spatial dimensions?", answer: "no"!
Afterwards there was a long queue to buy a signed copy of "Fashion, faith and fantasy in the New Physics of the Universe" (2016), I suspect some buyers will be surprised by how technical it is!
Robert Deuchar.
26th March 2017
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"The Order of Time", by Carlo Rovelli, ISBN 978-0-241-29252-5, published in April 2018.
This short book (182 pages) follows on from "Reality is not what it seems" and goes over much of the same subjects (time, space, gravity) but explains better how time may be "emergent". Quite a lot of it is "technical" but the reader can skip those bits. Rovelli says, rightly, that some of what he has written is controversial or conjecture. He hopes that the rivalry between his favoured theory, loop quantum gravity, and string theory will soon be settled. To quote from page 81: "There is no single time: there is a different duration for every trajectory; and time passes at different rhythms according to place and to speed. It is not directional: the difference between past and future does not exist in the elementary equations of the world; its orientation is merely a contingent aspect that appears when we look at things and neglect the details... The notion of the "present" does not work... The substratum that determines the duration of time is not an independent entity, different from the others which make up the world; it is an aspect of a dynamic field. It jumps, fluctuates, materializes only by interacting, and is not to be found beneath a minimum scale. So, after all this, what is left of time?" It is challenging stuff, at the frontier of physics. I strongly recommend it. Bravo again, Carlo.
Having read it once I now understand much better how time may be "emergent". Also he is good on entropy, always a difficult area for me. It is a very "cultural" book with lots of literary and historic sources quoted. Interesting too to read his thought on death on reaching the age of 60.
Marks out of ten: ten.
Should I read it? If interested in physics, yes, definitely.
Regards,
Robert Deuchar.
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