Physics – Scienceandsf -A Blog Published by Robert A. Lawler

As Searches for Dark Matter continue to come up empty Physicists are beginning to reconsider theories of Modified Gravity.

Physicists and Astronomers have had a big problem now for a very long time. Once astronomer Carl Hubble recognized that a large number of the fuzzy objects out in space called nebula were in fact entire galaxies astronomers and astrophysicists starting trying to work out the dynamics of how those galaxies behaved. Take a typical spiral galaxy like our own Milky Way, it has a central globe about 20,000 light years in diameter surrounded by a thin disk 200,000 light years in diameter but only about 5,000 light years thick, see image below. The density of stars is greatest in that central sphere and slowly but steadily decreases the further out you go along the disk.

The galaxy M33 (Triangulum) is a typical spiral like our Milky Way with a concentration of stars in the center and the density growing less the further you go out from the center. (Credit: Astronomy Picture of the Day – NASA)

Physicists immediately recognized that such a galaxy would only be stable if all of its stars orbited around the center and indeed our Sun is calculated to orbit around the Milky Way’s center once every 200 million years. If astronomers could estimate the mass distribution of the stars then the physicists could use Newton’s law of gravity to work out a velocity profile for the galaxy. Basically that would give them a formula for the velocity a star would have as a function of its distance from the center of its galaxy. That formula could then be checked by using the Doppler effect to measure the actual velocities of stars at various places in a galaxy.

Capculated (expected) versus measured radial velocity as a function of distance from center for the spiral galaxy M33. It’s easy to see that something is wrong somewhere! (Credit: Dark Energy, Dark Matter, Dark Gravity)

It didn’t work. Dozens of studies, dating back to 1933 have shown that the stars near the outer edge of a galaxy are moving too fast. Indeed the whole profile of velocity versus distance indicated that galaxies should have more than twice the mass that we can see and that mass should be spread out more evenly from the center.

That’s where the idea of ‘Dark Matter’ comes from, some form of matter that doesn’t radiate light but possesses a great deal of mass. There have been a lot of ideas about what dark matter could be, several of which have even been given ‘cutesy’ names. MACHOS, which stands for Mass Concentrations, could be anything from brown dwarfs, objects too small to become stars but larger than planets, to stellar mass black holes. Problem with either alternative is that you need huge numbers of them; remember we have to more than double the mass of the galaxies. Astronomers have found a few brown dwarfs and stellar mass black holes but nowhere near enough to solve the problem of the missing mass.

Every now and then a physicist will suggest that Dark Matter is an enormous number of undetected primordial black holes. There is no evidence to support that idea and circumstantial evidence against it. (Credit: The Tribune)

Then there are the WIMPS or Weakly Interacting Massive Particles. These are elementary particles like electrons or quarks except that they are electrically neutral so they don’t interact with light, and they are very massive. Particle physicists like WIMPS because they can connect them to the particles predicted by theories of ‘Super-Symmetry’. Problem is that despite decades of searching, and building powerful particle accelerators like the Large Hadron Collider (LHC) at CERN no evidence for any super-symmetric particles has ever been found.

One of the problems with Weakly Interacting Massive Particles (WIMPS) as Dark Matter is that there are so many possibilities that it’s hard to keep them all straight. (Credit: Physics (APS) American Physical Society)

A completely different approach was taken back in 1983 by Israeli physicist Mordehai Milgrom. Maybe he asked, Newton and Einstein were wrong about gravity, and then Milgrom proceeded to modify the gravitational field equations so that they would accurately predict the behavior of galaxies. Milgrom referred to his theory as MOdified Newtonian Dynamics or MOND the name by which it has since been known. If MOND or some similar altered theory of gravity is true then the failure to detect dark matter is easy to understand, there simply is no such thing as dark matter, gravity is different than what we thought.

Physicist Mordehai Milgrom has challenged both Newton and Einstein, not something for the faint of heart to try! (Credit: Wikipedia)

Now according to Newton and Einstein gravity obeys what is known as an inverse square law, see equation. 1. This means that the strength of gravity gets weaker the further two masses are by the square of the distance between them. Double the distance and gravity is one quarter as strong, triple the distance and gravity is one ninth as strong, four times the distance yields one sixteenth the strength and so on.

Newton’s law of Gravity is an Inverse Square Law and has been measured to be extremely accurate within our Solar System. (Credit: Wikipedia)

The changes Milgrom proposed to the inverse square law where very small. They had to be because Newton-Einstein works extremely well in our solar system and recently astronomers have even shown that stars orbiting around the supermassive black hole at the center of our galaxy follow Newton-Einstein very accurately, see my post of 6May2020. Crucially however, the small change proposed by Milgrom doesn’t grow weak as quickly with distance as inverse square. This means that at enormous distances, much larger than our solar system, tens to hundreds of light years, it is the modified term that starts to dominate over the Newtonian inverse square term.

In MOND a constant Ao is introduced that must be extremely tiny so that MOND only differs from Newton over huge distances. Physicists don’t like this kind of tweaking of equations just to make them fit the observed data without some rational behind it. (Credit: Slideserve)

All that makes it very difficult to test MOND or any similar small changes to Newton-Einstein. There is one difference however that just might be measured. One of the quirks of a pure inverse square law is that if you are sitting at the center of a mass distribution then you are being pulled by the gravity of those masses equally in every direction so that you literally feel no force! Think about it, if you are at the center of a planet there is a lot of matter all around you but you’re being pulled down just as much as up, back just as much as forward and to the left just as much as to the right. Being pulled equally in every direction you end up not being pulled in any direction, so you feel no gravity. This is known as the lack of effect from an external field.

Newton first performed the calculation that showed how there is no net gravitational force inside a uniform shell of matter. (Credit: Slideplayer)

In MOND however an external field can be felt and so the rotation curve of a galaxy at the center of a large cluster of galaxies would differ from the rotation curve of a similar galaxy that is far from any other large galaxy. To test this idea a group of astrophysicists from Sejong University in South Korea, Cardiff University and the University of Oxford in the UK along with Chase Western Reserve University and the University of Oregon in the USA has examined the rotation curves of 153 galaxies to see if there is any trace of such a difference. The study is entitled ‘Testing the Strong Equivalence Principle: Detection of the External Field Effect in Rotationally Supported Galaxies’ and has been published in the Astrophysics Journal.

What they discovered was that of rotational speeds of galaxies inside an external gravitational field were slowed when compared to the rotations in more isolated galaxies, something contrary to Newton-Einstein but exactly as predicted by MOND. Statistically the results so far give a 4σ confidence level, just below the golden 5σ confidence that physicists use to declare a ‘discovery’. With results so provocative you can be certain that the researchers will be working to both find more evidence as well as improve the data they already have.

Some of the data from the study in Astrophysical Journal in chart form. (Credit: Kyu-Hyun Chae et al)

If MOND does turn out to be correct it will not only eliminate the need for dark matter it will force a reevaluation of many other well established theories. Much of Cosmology and the Big Bang Theory are rooted in Einstein’s gravitational field equations but so far no one has ever been able to expand MOND to describe the Universe as a whole. So even while MOND has gained strong new evidence in its favour there’s still a long way to go before it becomes generally accepted by the majority of physicists. The problem of galactic rotation has been around a long time and it looks like it will continue to be so for a little while longer.

The Nobel Prizes for 2019 are awarded.

It’s that time of year again. The Nobel Committee has announced its choices for the award that recognizes achievements in the fields of Physics, Chemistry and Medicine (Physiology). Since my degree is in physics I think I’ll start with the winners for Physics.

This years winners are being recognized for their work in revealing some of the details about the structure of this Universe in which we live. Three scientists, James Peebles along with Michel Mayor and Didier Queloz will share this year’s prize of 9 million Swedish krona or $910,000 dollars.

James Peebles, Michel Mayor and Didier Queloz were awarded the 2019 Nobel Prize in Physics for their work in Astrophysics. (Credit: Bloomberg)

Two of the physicists, Professor Michel Mayor of the University of Geneva along with Didier Queloz, who teaches at both the University of Geneva and Cambridge University were honoured for their discovery in 1995 of the first exoplanet orbiting a Sun like star. Today we know about the existence of thousands of exoplanets but it was Mayor and Queloz who used a technique called the Radial Velocity Method to discover an exoplanet orbiting the star 51 Pegasi, in the constellation of Pegasus.

Looking at the illustration below of a star and its planet both orbiting around their mutual center of gravity we see how the star is sometimes moving toward us and sometimes away from us. This tiny tug back and forth due to the gravity of the planet can be seen in a blue shift in the star’s light as it moves toward us and a red shift as it moves away. It was by detecting a repeating pattern of blue and red shifts in the light of the star 51 Pegasi having a period of 4.2 days that allowed Mayor and Queloz to announce their discovery.

An Illustration of the Radial Velocity Method for discovering exo-planets. (Credit: Johnan Jarnestad/ Swedish Academy of Science)

The work of James Peebles of Princeton University, the Albert Einstein Professor of Physics no less, deals with a topic a bit bigger and older than a mere planet, the birth of the Universe itself. You see Peebles, working back in the 1970s, was one of the leading scientists who put the Big Bang Theory on a solid theoretical basis.

Doctor Peebles work dealt with probing the Cosmic Microwave Background (CMB) for clues about not only the conditions that prevailed in the Universe at the time of the Big Bang but also in the Universe as it is today. The cosmic Microwave Background is the tiny amount of heat left over from the Big Band that permeates the entire Universe and is almost, almost the same temperature everywhere and in every direction.

The Cosmic Microwave Background as seen by the Planck Satellite. The tiny differences in temperature seen here were predicted by James Peebles. (Credit: Universe Review.ca)

It was Doctor Peebles who first predicted that tiny fluctuations in the CMB had to be there. If the CMB was perfectly smooth he reasoned, then the Universe today would also be perfectly smooth, instead of possessing all of the galaxies and stars we see. In other words those tiny variations in temperature 13.8 billion years ago were the seeds from which the structure of today’s Universe grew.

Further analysis of those variations also allowed Peebles to calculate the percentage of the energy of the Universe that today is composed of ordinary matter, the atoms and elementary particles we are familiar with, dark matter and even dark energy which are the subject of so much current research. When you consider how much of our knowledge of the early Universe is due to the work of James Peebles it’s no wonder he has finally received the Nobel Prize.

Since you’re reading this post right now there’s a good chance that you’re using either a smartphone, smartpad, or laptop computer. If so you might want to take a moment to thank the winners of this year’s Nobel Prize in Chemistry. You see the research for which M. Stanley Whittingham, John B Goodenough and Akira Yoshino will share their 7 million krona is the development of the Lithium-Ion batteries that today power our mobile world.

John B. Goodenough, M. Stanley Whittingham and Akira Yoshino received this years Nobel Prize in Chemistry. (Credit: Swedish Royal Academy of Science)

The development took quite a long time and there were more than a few problems along the way to overcome. It began in the 1970s when Stanley Whittingham discovered an energy rich material called titanium disulphide that he used as the cathode, the negative terminal in a battery with a metallic lithium anode as the positive terminal. Whittingham used lithium because of the metal’s ability to release large numbers of electrons.

Lithium Ion Batteries are a fixture in our modern world. (Credit: B&H)

The problem with these early lithium batteries was that each time the battery was recharged there was an internal buildup of chemicals at each terminal. This buildup would continue until the two terminals actually touched each other inside the battery causing a short circuit that released all of the battery’s energy in seconds. The result of that short would be either a fire or even an explosion. Despite this danger lithium batteries were so powerful that they quickly found some limited applications.

The Charge and Discharge mechanisms of a Lithium Battery. (Credit: ResearchGate)

Then in 1980 John B. Goodenough made lithium batteries even more powerful by replacing the disulphide terminal with one composed of cobalt oxide that nearly doubled the energy storage capability. Nevertheless the danger inherent in the lithium battery still kept them from widespread use.

It wasn’t until 1985 that Akira Yoshino succeeded in replacing the metallic lithium with Lithium Cobalt Oxide (LiCoO₂) alleviating the buildup of chemicals and making the new lithium ion battery safe enough for widespread use. Thanks to the efforts of these three dedicated scientists the development of the modern lithium ion battery is a case study in how engineering research is carried out, one step at a time. Certainly an achievement worthy of a Nobel Prize.

Also announced this week was the Nobel Prize in Medicine awarded to Doctors William G. Kaelin of Harvard University, Gregg L. Semenza of Johns Hopkins University along with Peter J. Ratcliffe of the Francis Crick Institute and Oxford University. The trio was recognized for their work in understanding how cells adjust their metabolism to match the availability of oxygen.

The 2019 Nobel Prize in Medicine was awarded to William G. Kaelin, Sir Peter J. Ratcliffe and Gregg L. Semenza. (Credit: Swedish Royal Academy of Science)

We are all aware of just how necessary oxygen is for life; the cells of our body will quickly begin to die without that gas. However cells can reduce the amount of oxygen they require whenever oxygen levels become lower. Our bodies experience such reduced oxygen levels during many activities such as swimming or other exercise, or while at high altitude.

More importantly however many people experience low oxygen levels for long periods of time due to lung or heart disease or anemia. In fact the knowledge gained by Doctors Kaelin, Semenza and Ratcliffe is already being put to use to develop drugs that will help patients with those aliments to make better use of the oxygen in their systems and live healthier lives.

For patients suffering with Heart or Lung problems a lack of oxygen is a serious threat. (Credit: Healthline)

The discovery may also be important in the treatment of cancer. You see it has long been known that cancer cells signal other cells in our body to build new blood vessels to them that increases their flow of oxygen enabling the tumors to grow even faster. It is possible that this research may lead to techniques that prevent this increased blood flow thereby slowing the growth of cancerous tumors.

The work of these three Nobel laureates gives our medical science another tool to both fight disease and to understand how living creatures work. Each year the Nobel Prizes are awarded to recognize the best, the most significant discoveries in science. It’s important to remember however that there are many smaller, but still significant advances. All of these discoveries combine to add to our ever increasing knowledge of the natural world.

Nobel Prizes for 2018, Medicine, Physics, Chemistry.

The first week of October is always an exciting time in the scientific community; it’s when the Nobel Prizes are announced. The order of announcement changes ever year and this year it went Medicine, then Physics and finally Chemistry so I’ll follow that order as well.

The two winners of the 2018 Nobel Prize in Medicine and Physiology are Doctors James P. Allison of the University of Texas M. D. Anderson Cancer Center and Tasuku Honjo of Kyoto University. The research conducted by the two scientists consisted in both understanding why our immune systems refuse to attack the cancer cells that are destroying our bodies along with discovering the first drugs that enable our immune systems to fight cancer.

2018 Nobel Prize Winners in Medicine. Tasuku Honjo (l) and James Allison (r) (credit: The Daily Star)

This has always been the biggest difficulty in fighting cancer, because cancer cells are actually our own cells gone berserk the white blood cells in our immune system won’t fight them. For decades scientists have searched for some way to alert those white blood to attack the cancer cells.

Drs. Allison and Honjo worked by studying the chemical ‘checkpoints’ that white blood cells use to recognize ‘friendly’ cells. Dr. Allison succeeded in identifying one such checkpoint that he called CTLA-4 while the checkpoint Dr. Honjo discovered he named PD-1. Once these two checkpoints were understood it became possible to develop drugs that inhibited their function. Without the correct recognition signal the white blood cells now attacked the cancer cells.

This new technique is not without its problems. For one thing it is expensive, the chemical checkpoints differ for every person. For another the drug sometime simply fail to work and rarely they can even cause the patients immune system to begin attacking healthy cells. Nevertheless, checkpoint inhibitors as the drugs are known, have brought miraculous recoveries in patients whose cancer had been deemed untreatable by other techniques. The work of Drs. Allison and Honjo has brought us a powerful new weapon into our fight against cancer.

The three winners for the 2018 Nobel Prize in Physics are all pioneers in the use of Lasers in both biology and medicine. Doctor Arthur Askin of Bell Laboratories received his share of the prize for his development of lasers as ‘Optical Tweezers’. You see the particles of light do have momentum and a beam of light can direct ‘radiation pressure’ on an object it strikes. This allowed Dr. Askin to employ the intense light of lasers to actually to hold and even manipulate tiny objects such as individual cells and even down to single atoms.

2018 Nobel Prize winners in Physics, Donna Strickland (l), Gerard Mourou (c), and Arthur Askin (r) (Credit: The India Express)

The two other scientists sharing the physics prize are Doctor Donna Strickland of the University of Waterloo and Gerard Mourou for their work in high intensity, short pulse duration lasers. The work of Drs. Strickland and Mourou has had extensive applications in industry and medicine and is perhaps best known for it use in Lasik eye surgery.

This years physics Nobel also garnered some attention because Dr. Strickland became the first woman in fifty-five years to receive the award, and only the third woman ever. The only comment I’ll make on that aspect of the award is that I hope the day soon comes when the sex or ethnicity of a Nobel Prize winner is a matter of no importance whatsoever.

Finally we have the 2018 recipients of the Nobel Prize for Chemistry who are Francis H. Arnold of the California Institute of Technology along with George P. Smith of the University of Missouri and Sir Gregory P. Winter of the MRC Laboratory of Molecular Biology at Cambridge, UK. All of these scientists have worked in the field of organic chemistry with some of the most complex chemicals known to science.

Chemistry Nobel Laureates for 2018. Gregory P. Winter (l), Francis H. Arnold (c), and George P. Smith (Credit: NPR)

Doctor Arnold’s research has concentrated on “the directed evolution of enzymes” those organic catalysts that perform so many important functions in living creatures. Meanwhile Dr. Smith developed a technology known as ‘phage display’, using a virus that infects bacteria to develop new forms of proteins while Dr. Winter used phage display to direct the evolution of antibodies, thereby producing new pharmaceutical drugs. Many drugs are now being developed by this technique including some that neutralize toxins, combat rheumatoid arthritis, psoriasis and other autoimmune diseases.

The yearly choice of those scientists who receive the Nobel Prize is often the only time that the important work being carried out by scientists receives any publicity in the news media. Perhaps, given the acrimonious, contentious and partisan nature of so much of our news these days it might do us good if our nightly news programs spent a little more time on stories about the advances of science being made everyday. Stories like those about this year’s Nobel Prize recipients.

Science and Science Fiction: Top Stories and the Year 2017 in Review

We’re down to the last few days of the year 2017 and all of the news outlets are doing special reviews of the ‘Top Stories’ that they covered during the past year. With this in mind I’ve decided to use my final post of the year to review some of the stories I’ve written about in 2017.

First of all let’s look at some of the numbers. Over the past 52 weeks I’ve now published 102 posts so it hasn’t quite been two posts a week. Of those posts 88 have dealt with topics in one of the many fields of science while 13 have been reviews of science fiction novels or movies. (Looking at these statistics I realize I need to do some more SF posts.)

Starting with the science we’ll begin by looking at some the events that took place in man’s continuing exploration of space. A lot happened both with robotic probes throughout the Solar System as well as preparing for future manned mission beyond low Earth orbit. In my opinion however the big story in space has bee the continued success of Space X corporation. (posts of 8Mar, 1Apl, 17May, 7Jun and 14Oct)

Space X, the Hawthorn California based commercial space launch company, succeeded in launching 18 of their Falcon 9 rockets in 2017 placing a variety of satellites into orbit including two resupply mission to the International Space Station (ISS).

In addition to launching 18 of their rockets Space X also able to land 16 of the rockets. (The two that were not recovered were not failures but rather missions requiring so much fuel that a recovery was not possible.) Indeed one of the Falcon 9 rockets that flew this year had already flown in 2016 and represented the first reuse and re-recovery of the Falcon 9.

With these successes Space X has proven beyond doubt its ability to reliably reuse the Falcon 9 and hopefully this will soon lead to a considerable reduction in the cost of getting into space. The image below shows the last Space X launch of 2017, one from Vandenberg Air Force Base and which gave the southern half of California a spectacular show.

On the interplanetary exploration side of space the biggest news came from the arrival of the Juno spacecraft at Jupiter (19Jul) along with the Cassini Spacecraft’s ending its mission to Saturn with a final plunge into the atmosphere of the planet itself (15Apl, 13Sept and 14Oct). Juno has already given us the closest views ever of the biggest planet in our Solar System and has allowed scientists to study phenomenon like the great red spot in greater detail. The image below is the Great Red Spot from the Juno spacecraft.

Great Red Spot (Credit: NASA/JPL-Caltech/SwRI/MSSS/Jason Major)

The Cassini spacecraft had already been orbiting Saturn for more than a decade sending back breathtaking images of the Solar Systems most beautiful planet (My opinion) and its mission was coming to an end due to lack of fuel. Because the data sent back by Cassini had indicated the possibility that two of Saturn’s moons, Titan and Enceladus might harbour life it was decided to send the probe to burn up in the giant planet’s atmosphere rather than risk contaminating those moons. The image below is one of the last from Cassini.

For manned space flight the year 2017 was more a waiting year as the ISS continued to be manned by Russian spacecraft but America is still hoping Space X and Boeing will begin test flights of their new manned capsules in 2018.

In the political / budget front President Trump ordered NASA to plan on a return to the Moon but there was no mention of money so no bucks, no Buck Rogers (16Dec).

In the science of Paleontology this has been a year of new discoveries along with the resolution of some long standing mysteries. New dinosaur species included the Patagotitan (16Aug), the Kayentapus (known only from its footprints) and the Sinosauropterys (both 28Oct). See images below.

Patagotitan mayorum skeleton (Credit: Museo Egidio Feruglio)

Sinosauropteryx Fossil (Credit: Jacob Vinther)

For those of us who love Trilobites, and who doesn’t, we had the most detailed description ever of the digestive system of a trilobite (29Nov). There was also a paper examining the earliest known eye that was found on a fossil trilobite (9Dec). The image below is the fossil trilobite with the earliest known eyes.

Trilobite Fossil with earliest evidence of Eyes (Credit: Gennadi Baranov)

To me however the biggest news in paleontology came from a paper examining the anatomy of the ancient extinct creatures called hyoliths, small conic shaped fossils whose taxonomic place among living things had been a mystery for almost 200 years (15Jan). After studying and dissecting, yes they can dissect fossils, the best specimens of hyoliths it was found that hyoliths belonged in the same group of animals that contained the brachiopods. The image below shows an artist’s representation of a hyolith.

Now I’m a physicist by training so in the past year there were a lot of posts about new developments in that field. The detection of gravity waves at the Laser Interferometer Gravitywave Observatory (LIGO) probably being the most noteworthy (14Jan, 7Oct and 22Oct). In fact the observation of gravity waves won the Nobel Prize for the chief scientists at LIGO Rainer Weiss of the Massachusetts Institute of Technology (MIT) along with Kip Thorne and Barry Barish of the California Institute of Technology (Caltech).

Now the first two observations of gravity waves both came from the merger of two black holes and as you may guess aside from the gravity waves there was little else to see. The third detection on August 17th however was caused by the merger of two neutron stars resulting in an explosion so huge that it produced enough radiation to be picked up by a Gamma Ray satellite along with optical and radio telescopes. The fact that we can now integrate gravity wave observations with the observations of other astronomically instruments opens up entirely new ways of studying the Universe.

I also wrote two posts about new experiments to study the sub-atomic particles called neutrinos, the ghost particle of the atom. In particular I wrote about the design and construction of the Deep Underground Neutrino Experiment (DUNE) (30Jul and 2Dec). Now the DUNE experiment will use the Tevatron particle accelerator at Fermi-Lab to produce large streams of neutrinos that will travel beneath the Earth to a huge neutrino detector in an old gold mine outside of Lead, South Dakota. (Neutrinos interact so rarely that hardly any will be absorbed). The way the neutrinos change during the 2000km flight will tell us a great deal about this most mysterious of elementary particles. The image below shows the setup of the DUNE experiment.

DUNE Experimental Layout (Credit: Fermilab)

Oh, and before I forget there was the post about my trip down to Sweetwater Tennessee to view the ‘Great American Eclipse of 2017’ (24Aug). It really was an awesome sight that I’ll never forget. The Image below is one of my pictures of the eclipse.

Total Eclipse of the Sun (Credit: R.A.Lawler)

Now as I said earlier most of my posts have dealt with science but during the past twelve months I did get to review three SF movies and six novels, I even spend four posts describing what Science Fiction is in my opinion.

The three movies I reviewed were: Guardians of the Galaxy vol.2 (20May), Blade Runner 2049 (25Oct) and Thor, Ragnarok (15Nov). All of them were interesting but all of them had their faults as well. To my mind a really good SF movie is that rarest of gems that only comes around once a decade or so. Oh well, I guess maybe I’m just asking for too much.

The same is pretty much true of the six novels I reviewed. The novels were: Dark Secret by Edward M. Lerner (18Jan), New Moon by Ian McDonald (1Mar), Saturn Run by John Sandford and Ctein (12Apl), Death Wave by Ben Bova (31May), the Three Body Problem by Cixin Liu (30Aug) and Galactic Satori Chronicles Book 1: Earth by Nick Braker and Paul E. Hicks (27Sept). Each of these novels would appeal to some but the one I found most interesting and best written was The Three Body Problem by Cixin Liu. The image below shows the cover of the Three Body Problem.

Cover The Three Body Problem (Credit: Tor Books)

Well this has been quite a long post but then it’s been a long year and a lot happened. I’m sure that next year will be just as interesting; I hope you’ll stop by on occasion to check out ‘Science and Science Fiction’.

Physics Seminar: Free Neutron Decay

Back in High School you probably learned that the atoms that make up everything around us are themselves made up of three types of particles, Protons and Neutron sit at the center of the atom in the nucleus while electrons go spinning around the nucleus. What you might not have learned in High School is that the Protons and Neutrons are made up of particles called quarks and that sometimes Neutrons can ‘decay’ into a Proton, electron and an anti-Neutrino!

Two days ago I attended a physics seminar at my old Alma Matter Drexel University entitled “The Life and Death of the Free Neutron’ given by Doctor Nadia Fomin, Assistant Professor at the University of Tennessee and a researcher at Oak Ridge Laboratory and the National Institute of Standards and Technology (NIST).

For those of you who have never had the pleasure of attending a science seminar let me take a brief moment to give you an idea of what it’s like. A visiting scientist is invited to come and give a talk by a member of the local faculty whose own research is in the same general field. First there is an introduction by the local faculty member mentioning where the visitor is currently working, where they received their degrees and a short description of their research.

Then we get the meat! For the next 45 minutes or so you get to listen to a lecture on the latest research being conducted, the cutting edge of science in action. If the visitor is an experimentalist as Doctor Fomin was you get to hear about the development of their instruments as well as their results but if the visitor is a theoretician you could be treated to 45 minutes of solid math, what could be better than that! After presenting their results the lecturer will then take about 5 minutes to relate what they think their results mean, how they effect what we know about the Universe. Finally there’s about ten minutes given to questions from the audience.

The question period can be the most interesting. I have attended several seminars where a member of the audience was well known to disagreed with everything the visiting speaker was saying and everybody else was just waiting for the clash when the two scientists argued their case. Now there’s no yelling or cursing, everything is calm and deliberate but this is the cutting edge of science in action. Two opposing models of how the Universe behaves, each side has some evidence and a lot of theories as support but neither side has enough to convince the other.

So that’s what attending a scientific seminar is like. Let’s get back to Professor Fomin and her measurements of the decay half life of a free Neutron. Ever since the Neutron was discovered by James Chadwick in 1932 scientists have know that a free Neutron, one that was not confined to the nucleus of an atom, would after some time decay into a Proton and an electron and it was some missing energy in this decay that led Wolfgang Pauli to predict the existence of the Neutrino (although in Neutron decay it’s actually an anti-Neutrino that gets produced). To understand the reaction take a look at the Feynman diagram below.

The Neutron and Proton are both composed of three quarks, two Ups and a Down for the Proton and two Downs and an Up for the Neutron. Now the decay of the Neutron takes place via the ‘Weak Nuclear Interaction’ and it’s half life was first measured after world war 2 to be something around 15 minutes. That doesn’t sound very scientific does it, well Neutrons are very hard to measure, they’re much smaller than an atom, they have to electric charge so it takes a lot effort to learn almost anything about them.

We have made progress since the 1940s, and Doctor Formin and her colleagues are a part of that progress. The best current estimate of the free Neutron half life is between 870 and 880 seconds and the hope is that with new instruments before long that range will be reduced to 0.3 seconds.

Why should we care? What difference does it make whether the Neutron’s half life is 874 or 875 seconds? Well, it does matter because the half life of the Neutron plays an important role in models of the early development of our Universe. Shortly after the Big Bang the universe was a foaming sea of elementary particles that quickly became atoms of hydrogen and helium along with a bit of lithium. Right now the biggest unknown in just how that process took place is the Neutron half life! Also, numerous theories uniting gravity to quantum mechanics, the so called ‘Theories of Everything’ make predictions about the half life of the Neutron and with a better measurement of the half life we can eliminate some of the wrong theories.

Physics began some four hundred years age with Galileo making measurements of falling objects. Measurement is central to what physics is and how it works. I look forward to hearing about Doctor Formin’s results when she gets her new instruments.

Welcome to 2017. What to look forward to in Science in the coming Year

Well it’s 2017 and I thought it might be nice to take some time to see what scientific discoveries and achievements we can expect in 2017.

For me the most exciting event may be the upcoming TOTAL ECLIPSE of the SUN going across the USA on August the 17th. The path of totality is pretty narrow but it goes from sea to shining sea so if you really want to see it you only need to drive a day or two to get there. Here’s a link to a site giving all the details.

http://www.eclipse2017.org/2017/path_through_the_US.htm

Other Space events we can look forward to include the Cassini’s spacecraft’s final orbits through Saturn’s rings and it’s final plunge into the planet itself. Cassini has already given us so many discoveries but I’m sure there will be a few more to come.

Also coming up this year will be a Chinese unmanned Lunar mission which will hopefully bring back some samples making China only the third nation to bring back pieces of the Moon. China also plans on continuing their missions to their new Tiangong-2 space station including their first unmanned resupply vehicle the Tianzhou-1.

Meanwhile NASA is continuing development of their Space Launch System (SLS) which will eventually be the biggest rocket ever built, a bit bigger than the Saturn 5. The actual first launch of the SLS is scheduled for early in 2018.

Commercial development of space will continue as Space X and Orbital Science continue to resupply the International Space Station. Additionally Space X and Boeing will continue development of their manned spacecraft including unmanned test launches. The first manned missions for both Space X and Boeing are scheduled for early 2018 under NASA’s Commercial Crew Development Program. Space X also intends to perform the first re-launch of one of their previously used Falcon 9 rockets in the first half of 2017 along with the first flight of their Falcon Heavy rocket.

In Physics of course there’s the possibility of new discoveries coming from the Large Hadron Collider (LHC) at CERN. As the world’s largest and most power scientific instrument the LHC in well into it’s second full scale run after completing an upgrade in 2015. The LHC’s initial run only gave us the confirmed detection of the Higgs Boson and with its increased power maybe this year the LHC will finally provide firm evidence for, or against Supersymmetry.

Another series of experiments going on at CERN is the Alpha experiment to study anti-hydrogen. The Alpha team have made great progress in containing and cooling anti-protons and positrons, allowing them to form actual atoms of anti-hydrogen. Anti-matter, just like in Star Trek! The researchers are looking for some tiny difference between anti-hydrogen and normal hydrogen, a difference that could help to explain why our Universe appears to be made almost entirely of matter only.

There will surely be great discoveries in the fields of Paleontology and Archeology as well but it’s hard to predict just which team of researchers will make the big finds. There’s a element of luck in finding fossils and relics as you can imagine.

So we should have a lot to look forward to in the coming months. Scientific progress can sometimes be expected, but just as often you cannot predict what amazing new discoveries will be made. Of course that’s a big part of the fun. I’ll keep you informed of anything interesting I hear about.

Have Scientists discovered a Fifth Force of Nature. Probably not, but it would be really cool

During the past week there’s been a lot of talk about Theoretical Physics at the University of California Irvine analyzing data from the Institute for Nuclear Research at Debrecen Hungary, some news articles have even called the UC Irvine analysis a conformation. What’s all this about.

First of all, a little background. Modern Physics recognizes four Forces of nature: Gravity, Electromagnetism and two Forces that only work over the immensely short nuclear distances. These are called the Strong (or color) force and the Weak force.

For nearly forty years now physicists have been looked for something beyond the standard model of particles and forces because the standard model cannot describe gravity at the nuclear scale, nor does it describe the motions of galaxies attributed to “Dark Matter” nor finally the accelerated expansion of the universe attributed to “Dark Energy”.

Now, what the researchers in Hungary were doing was to take nuclei of Lithium and bombard them with energetic protons turning them into nuclei of Beryllium in an excited state, excited state in important. The excited Beryllium nuclei would then sometimes decay into Beryllium in the ground state by emitting a gamma ray photon (a very high energy particle of light) and the gamma ray would then split into an electron-positron pair.

Measuring the energy spectrum of the gamma rays the group in Hungary found a bump at an energy of 17 million electron volts that could be due to a particle other than the gamma photons, an unknown particle. The theoreticians at UC Irvine then looked at the Hungarian data and determined that the new particle would be a force carrying Boson. The data implied not just a new particle but a new force.

First of all, the work at UC Irvine is not a conformation it is an analysis. Conformation requires another laboratory to replicate the data from Hungary. Fortunately the energy levels involved are low enough to allow many laboratories to do the experiment and confirm the Hungarian’s work, or otherwise. we should have an answer soon, a year or so.

This is the fourth time in my career someone has announced a fifth force and each time previously the new force quickly disappeared when subject to additional scrutiny. I’m hopeful, because a new force would be really cool, and I’ll keep reading the published articles, but I’m not holding my breath.