Friday, June 15, 2018

Is Theoretical Physics Wasting Our Best Minds?

Before you continue reading this, let me be very clear right off the bat that there are TWO separate issues here that I will be discussing, and they are thinly connected simply by the over-general reference of "theoretical physics" made by the author of the article that I will be citing.

In this Forbes article, Ethan Siegel highlights the main point made by Sabine Hossenfelder in her book "Lost In Math". Siegel not only pointed this out, but also did an in-depth description leading up to the "naturalness" philosophy that is prevalent in the esoteric fields of physics such as string, etc.

If you are a theoretical particle physicist, a string theorist, or a phenomenologist — particularly if you suffer from cognitive dissonance — you will not like this book. If you are a true believer in naturalness as the guiding light of theoretical physics, this book will irritate you tremendously. But if you're someone who isn't afraid to ask that big question of "are we doing it all wrong," the answer might be a big, uncomfortable "yes." Those of us who are intellectually honest physicists have been living with this discomfort for many decades now. In Sabine's book, Lost In Math, this discomfort is now made accessible to the rest of us.

Certainly this is thought-provoking, and it isn't something I disagree about. For science to give up on empirical evidence, and simply pursue something that looks "natural" or "beautiful" is dangerous and verging on being a religion. So my feelings are consistent with what has been said in the article.

Now comes the other part of the issue. It has always been my pet peeve when someone over-generalize physics as being predominantly being "high-energy physics, astrophysics, string theory, etc...", i.e. the esoteric fields of study. In this case, "theoretical physics" certainly is NOT dominated by those fields. There are theoretical studies in condensed matter physics, atomic/molecular physics, medical physics, accelerator physics, etc... etc., i.e. fields of studies that are certainly not esoteric, have lots of practical applications, etc.

In fact, I would argue that the esoteric fields of physics represents the MINORITY in terms of the number of practicing physicists that we have around the world. As a zeroth-order approximation of this claim, I decided to look at the members of the APS. The APS Divisions correspond to the number of members who declared themselves to be in a certain field within physics. Note that not all members made the declaration, and it is also not uncommon for a member to declare more than one division.


First of all, 79% of APS members are accounted for in this chart for the 2018 membership. Now, what is the percentage of members within the so-called esoteric fields of Astrophysics, Gravitation, and Particles and Fields? 14.9%. Even if you include Nuclear Physics into this, it will come up to 19.8%

Now, forget about theoretical or experimental. Can 19.8% represents ALL of physics? The fields of studies that a lot of people associate physics with are done by ONLY 19.8% of physicists! Using them, one will get a severely inaccurate representation of physics and physicists.

In fact, if you look at the fields more commonly associated with the physics of materials (condensed matter physics and Materials Physics), we get 18.2%, almost as big as Astrophysics, Gravitation, Particles and Fields, and Nuclear Physics combined! Condensed matter physics alone dwarfs other fields, being almost twice as big as the next division, which is Particles and Fields.

But what is more important here is that outside of the 19.8% of physicists in these esoteric fields, an overwhelming percentage of physicists (59.2%) are in fields of studies that are associated with practical applications of physics. So if you were to bump randomly into a physicist, chances are, you will find someone who works in a field related to something of practical importance and NOT a high-energy physicist, a nuclear physicist, etc.

This is my round-about way of complaining that Ethan Siegel article should not be a damnation of "theoretical physics" in general, because the overwhelming percentage of theoretical physics is NOT about these esoteric topics that have been mentioned in his article. Rather, theories in other parts of physics rely very heavily on empirical observations and verification, i.e. the good and tested way of doing science. In those areas, we are definitely NOT wasting our best minds!

A while back, I said that physics is not just the LHC. It is also your iPhone. Even that requires modification. We should say that physics is predominantly your iPhone, with only a smidgen of LHC added as garnishing. That is a more accurate representation of the field as a whole.

Zz.

Wednesday, June 13, 2018

MinutePhysics Special Relativity Chapter 6

If you missed Chapter 5 of this series, check it out here.

Here's Chapter 6 of the Minute Physics series on Special Relativity. This time, they are tackling a topic that I see being asked numerous times : velocity addition. ("If I'm traveling close to the speed of light and I turn on my flashlight.....").

I know that this topic has been covered here many times, but it is worth repeating, especially since someone may have missed the earlier ones.



Zz.

Tuesday, June 12, 2018

Work Begins On FACET II at SLAC

The upgrade to FACET facility at SLAC promises to improve the beam electron beam quality at the accelerator facility. One of the direct benefits of this upgrade is further advancement in the plasma wakefield accelerator technique. This technique has previously shown to be capable of producing very high accelerating gradient and thus, has the potential to produce accelerating structures that can accelerate charged particles to higher energies over shorter distances.

Now, when you read the press release that I linked above, make sure you are very clear on what it said. The FACET II facility is NOT a facility that operates using this "plasma wakefield" technique. It is a facility that produces an improved electron beam quality, both in energy and emittance, among other things. This electron beam (which is produced via conventional means) is THEN will be used in the study of this wakefield accelerator technique.

The project is an upgrade to the Facility for Advanced Accelerator Experimental Tests (FACET), a DOE Office of Science user facility that operated from 2011 to 2016. FACET-II will produce beams of highly energetic electrons like its predecessor, but with even better quality. These beams will primarily be used to develop plasma acceleration techniques, which could lead to next-generation particle colliders that enhance our understanding of nature’s fundamental particles and forces and novel X-ray lasers that provide us with unparalleled views of ultrafast processes in the atomic world around us.

So read carefully the "sequence of events" here and not get too highly distracted by thinking that FACET II is a "novel X-ray laser, etc..." facility. It isn't. It is a facility, an important facility, to develop the machines that will give us more knowledge to make all these other capabilities.

Consider this as my public service to you to clarify a press release! :)

Zz.

Wednesday, May 30, 2018

What Is A Plasma?

I love the Chicago's Museum of Science and Industry (MSI). In fact, I am a member and a donor to the museum. So let's get that out of the way first.

Secondly, I know how difficult it is to explain scientific concepts to the public. The need to use simple words and terminology, AND, make it accurate can be a daunting task.

Still, I can't help but be a bit disappointed by this sign that I saw at MSI this past week. Granted, this was in the gift store, but still, for an institution promoting science, this falls a bit short.

The sign accompanies one of those "plasma arc ball" thingy that they were selling:

Here's what the sign says:

A plasma is a gas that has been heated to extremely high temperatures. At these high temperatures, the atoms are moving so fast that they lose their electrons, creating ionized particles. The electrons and ionized particles jump from one place to another to try and get as far away from each other as possible, creating a "lightening" effect.

There are problems with this description.

1. A plasma need NOT be only a gas that has been heated to high temperatures. I can create a plasma by blasting gas atoms with energetic electrons. In fact, when you have an electrical discharge, that is essentially what happens. The gas has not been heated by any means. So there are other means of creating a plasma beyond just heating. So a plasma is NOT defined as ".... a gas that has been heated to high temperatures...."

2. At high temperatures, the atoms lose their electrons not because they are moving "so fast". They lose their electrons because when they move "so fast", they also collide harder against other atoms, and collide more frequently. This tend to give each atom the energy to knock off one or more electrons, thus causing it to be ionized. Atoms do not lose electrons simply because they are moving "so fast".

3. The description that "... The electrons and ionized particles jump from one place to another to try and get as far away from each other as possible, creating a "lightening" effect.... " is extremely puzzling and, frankly, irrelevant to the description of what a plasma is. In fact, if you think about it, when an atom is ionized, it has a net positive charge. An electron, having a negative charge, would tend to want to go back to the positively-charged ion. So why would they want to "... get as far way from each other as possible..."?

4. The last part is trying to describe the creation of an electric discharge or an arc. This is superfluous, and is not part of the definition of a plasma. An electric discharge is a form of a plasma, but a plasma is not JUST an electrical discharge.

So what is a plasma? If, say, someone at MSI who isn't a physicist needed to make this sign, and Googled it, he/she will see several definitions. I'll pick one (the bold is mine).

Plasma is the fourth state of matter. Many places teach that there are three states of matter; solid, liquid and gas, but there are actually four. The fourth is plasma. To put it very simply, a plasma is an ionized gas, a gas into which sufficient energy is provided to free electrons from atoms or molecules and to allow both species, ions and electrons, to coexist. The funny thing about that is, that as far as we know, plasmas are the most common state of matter in the universe. They are even common here on earth. A plasma is a gas that has been energized to the point that some of the electrons break free from, but travel with, their nucleus. Gases can become plasmas in several ways, but all include pumping the gas with energy. A spark in a gas will create a plasma. A hot gas passing through a big spark will turn the gas stream into a plasma that can be useful. Plasma torches like that are used in industry to cut metals. The biggest chunk of plasma you will see is that dear friend to all of us, the sun. The sun's enormous heat rips electrons off the hydrogen and helium molecules that make up the sun. Essentially, the sun, like most stars, is a great big ball of plasma.

The bold sentence, to me, is a sufficient definition of a plasma to be given to the general public. An ionized gas can be made up of equal parts of positive ions and electrons, unequal parts of positive ions and electrons, all ions, or all electrons, i.e. there are free charges floating around at a given time. This, to me, is a more accurate definition than what the MSI sign says.

I'm not sure how many of MSI guests paid attention to the sign or learned what a plasma is from that sign. But I hope those responsible for such signs pay closer attention to the accuracy of the info that they put out.

Zz.

Tuesday, May 29, 2018

MinutePhysics Special Relativity Chapter 5

If you missed Chapter 4 of this series, check it out here.

In this chapter, the topic of "time dilation" and "length contraction" is tackled.



Zz.

Wednesday, May 23, 2018

That Impossible EM Drive Might Be ..... Impossible After All!

Crackpots were just having a field day when NASA announced several years ago of an EM propulsion that somehow violates momentum conservation laws. Now comes a more careful experiment from a group that tried to reproduce this result, and the outcome is rather hysterical.

The team built their EM drive with the same dimensions as the one that NASA tested, and placed it in a vacuum chamber. Then, they piped microwaves into the cavity and measured its tiny movements using lasers. As in previous tests, they found it produced thrust, as measured by a spring. But when positioned so that the microwaves could not possibly produce thrust in the direction of the spring, the drive seemed to push just as hard.

And, when the team cut the power by half, it barely affected the thrust. So, it seems there’s something else at work. The researchers say the thrust may be produced by an interaction between Earth’s magnetic field and the cables that power the microwave amplifier.

So far, this has only been reported in a conference proceeding, which is linked in the New Scientist article (you will need ResearchGate access).

I'm sure there will be many more tests of this thing soon, but I can't help but chuckle at the apparent conclusion here.

Zz.

Monday, May 21, 2018

Graphene Might Could Kill Off Cancer Cells

Here's another example of how something that came out of physics is now finding an application in other fields, namely the medical field. Graphene, which was discovered quite a while back and won its two discoverers the Nobel Prize in Physics, has now found a possible application at fighting cancer.

It began with a theory -- scientists at the University of California knew graphene could convert light into electricity, and wondered whether that electricity had the capacity to stimulate human cells. Graphene is extremely sensitive to light (1,000 times more than traditional digital cameras and smartphones) and after experimenting with different light intensities, Alex Savchenko and his team discovered that cells could indeed be stimulated via optical graphene stimulation."

I was looking at the microscope's computer screen and I'm turning the knob for light intensity and I see the cells start beating faster," he said. "I showed that to our grad students and they were yelling and jumping and asking if they could turn the knob. We had never seen this possibility of controlling cell contraction."

The source paper can be found here, and it is open-access.

Again, this is why it is vital that funding in basic physics continues at a healthy pace. Even if you do not see the immediate application or benefit from many of these seemingly esoteric research, you just never know when any of the discovery and knowledge that are gained from such areas will turn into something that could save people's lives. We have seen such examples NUMEROUS times throughout history. Unfortunately, people are often ignorant at the origin of many of the benefits that they now take for granted.

Zz.

Thursday, May 17, 2018

Noether Theorem And Symmetries

This is not something new that I'm highlighting on this blog. I've mentioned a link to Emmy Noether theorem before in this post, and also highlighted a history of her work here. However, I think that there is no such thing as too much publicity on Emmy Noether, because she deserves to be remembered and admired through eternity for her accomplishments and insights.

This video tries to explain the significance of her work connecting conservation laws with symmetry principles.



However, I think that if I were a layperson, I'd miss the important point in this video. So here is the takeaway message if you want one:

Everything that we see and every behavior of our universe can be traced to some conservation laws. Each conservation law is a manifestation of some underlying symmetry of our universe.

This is the insight, and a very important insight, that Noether brought to the table, and it was revolutionary to physics. These symmetries are what we currently have as the most fundamental description of the universe that we live in.

Watch this video, and read the links that I gave above, several times if you must, because you owe it to yourself to know about this person and her immense effect on our understanding of our world.

Zz.

Relativistic Velocity Addition

If I get $1 for every time someone asks me "If I'm moving in a spaceship and I turn on my flash light...."

Here's Don Lincoln's lesson on relativistic velocity addition:



Zz.

Wednesday, May 16, 2018

RIP David Pines

This is another one of the physicist who is a giant in his field, but relatively unknown to the general public.

Renowned condensed matter theorist David Pines passed away on May 3, 2018 at the age of 93. I practically read his text (co-authored by Nozieres) on Fermi Liquid from cover to cover while I was a graduate student. In fact, he was on the cusp of a Nobel Prize when he was working with John Bardeen at UIUC. They published a paper on the electron-phonon interaction in superconductors in 1955, a paper that many thought was the precursor to the subsequent BCS Theory paper in 1957. Unfortunately, he left UIUC, and Bob Schrieffer took over his work on this, which ultimately led to the BCS theory and the Nobel prize.

This did not diminished his body of work throughout his life. He certainly was a main figure during the High-Tc superconductivity craze of the late 80's and 90's. His 1991 PRL paper with Monthoux and Balatsky and the 1992 PRL paper with Monthoux, both on the spin-fluctuation effect as the possible "glue" in the cuprate superconductors, where ground-breaking and highly cited.

His contribution to this body of knowledge will have a lasting impact.

Zz.

Monday, May 14, 2018

Dark Energy Levels Not Too Constrained For Star Formation

I've always had a bit of a problem with the anthropic scenario of our universe, i.e. the idea that we are living in a universe JUST fined-tuned to allow us to exist. My problem isn't with the observations so far, but rather how much people are already thinking that this must be true, the data are set, and that we can run away with it. Certainly many people outside of cosmology have tried to spin this into whatever directions that they want.

So when news like this comes along, I just want to yell "I told you so!". It is not that I agree or disagree with the conclusion, but it is to point out that in our attempt to understand all of this, our knowledge is still in its infancy, and that we really don't know enough yet to be able to say things one way or the other on many of the big issues. We do have a fuzzy idea on what direction it is going, but in a number of things and observations, more is required to understand things even better.

The new studies ran the simulation on the star formation of our universe against the amount of dark energy in our universe. They can, to put it crudely, dial in various level of dark energy in their simulations. They found that there is a wider range than initially expected for our present universe to form, i.e. it is not in a very narrow range that was thought of. So keeping everything relatively the same, we could see this present universe that we're in for a large range of dark energy.

The simulations allowed the researchers to adjust the amount of dark energy in the universe and watch what happened.

The results were a surprise. The research revealed that the amount of dark energy could be increased a couple of hundred times – or reduced equally drastically – without substantially affecting anything else.

So for dark energy, the parameter is not as "fine tuned" as one expected.

Zz.

https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/sty846/4963750?redirectedFrom=fulltext

https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/sty879/4966995?redirectedFrom=fulltext

Friday, May 11, 2018

Not Insignificant Blunder on John Bardeen by UK's "Express"

OK, so to commemorate Feynman's 100th birthday, the UK's Daily Express decided to do a "Top 10" about physics. I thought this was going to be a fun read when I encountered #8 on the list:


It said "8. The only double winner is John Bardeen: 1956 (transistors) and 1972 (MRI images)"

Nope! The 1972 Nobel Prize in physics to Bardeen was for the theory of superconductivity. He is the "B" in BCS theory!

The Nobel Prize for MRI imaging was given in 2003 to Paul Lauterbur and Peter Mansfield.

How come news organizations don't do fact checking anymore nowadays?

Zz.

Happy 100th Birthday, Richard Feynman!

Today, May 11, 2018, is the 100th birthday of physicist and Nobel Laureate Richard Feynman. He was born on May 11, 1918.

This article covers the important commemoration of Feynman's birthday, ranging from the event at CalTech all the way to Tuva in remote Russia.

Zz.