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.

Thursday, May 10, 2018

The Big Bell Test

Hey, I'm missing all the fun here!

A new paper to be published in Nature appears to have closed the "freedom-of-choice" loophole in the standard Bell-type experiment.

The BIG Bell Test asked human volunteers, known as Bellsters, to choose the measurements, in order to close the so-called "freedom-of-choice loophole" -- the possibility that the particles themselves influence the choice of measurement. Such influence, if it existed, would invalidate the test; it would be like allowing students to write their own exam questions. This loophole cannot be closed by choosing with dice or random number generators, because there is always the possibility that these physical systems are coordinated with the entangled particles. Human choices introduce the element of free will, by which people can choose independently of whatever the particles might be doing.
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Participants contributed with more than 90 million bits, making possible a strong test of local realism, as well as other experiments on realism in quantum mechanics. The obtained results strongly disagree Einstein's worldview, close the freedom-of-choice loophole for the first time, and demonstrate several new methods in the study of entanglement and local realism.

I have not read the actual paper yet, so if you have, I'd like to hear about it.

From my personal point of view, I no longer consider that the loopholes of Bell tests are anything significant anymore. This is due to the NUMEROUS consistent and non-contradictory results that we have obtained so far. In terms of the physics, Mother Nature seems to already let us know what she really is in this regards.

But I guess, until all of the loopholes are closed, we will always have to find a way to close them.

Zz.

Sunday, May 06, 2018

Alternative Theories of Gravity In Deep Doo-Doo

This is a rather nice article on the troubled times facing many alternative theories to Einstein's General Relativity due to the recent results from the colliding neutron stars. It should be especially useful to laymen to read and understand the methodology and the scrutiny that every theory goes through in physics to be considered to be valid. The one "take-home-lesson" that you should see is that my often-repeated manta here is more true than ever:

"Physics just doesn't say what goes up, must come down. It must also say when and where it comes down" - Warren Siegel.

The quantitative aspect is what is able to separate theories from being wrong to being right. One can't just say "oh, gravity gets weaker as we go farther away". It must say how much weaker, how it behaves with distance, etc.. etc.. and make precise predictions (i.e. to what level of uncertainty). These are "numbers" that we can compare with experiments, if there are already results or if new ones are collected.

This was exactly what happened with the merging neutron stars result, where our verification of the speed of gravity matches that to such precision with the speed of light, that a number of alternative gravitational theories died instantly.

The moral of the story here is that you should not fall in such deep love with any theory yet to have substantial verification, and you should not jump too quickly when new theories appear. I still point out to the OPERA debacle a few years ago when the OPERA project thought they measured superluminal neutrinos. As soon as they published their results, a bunch of theoretical explanations appeared on the e-print arXiv website, proposing theories of superluminal neutrinos, without waiting for independent verification of the validity of the result.

Not surprisingly, they all died of a horrible death when the result was attributed to bad optical cable connection! The history of physics is littered with theories that died and disappeared into obscurity when they could not match the experimental results or observations. Any beliefs or ideology, no matter how beautiful, satisfying, or popular, will crumble at the hands of Mother Nature if she says so.

Zz.

Wednesday, May 02, 2018

Hawking's Final Paper Is Published

The late Stephen Hawking's final paper written while he was alive, has been published. You can get the full version of it at that link.

If you missed it, read Ethan Siegel's earlier explanation of the paper.

Zz.

Friday, April 27, 2018

Quantum Entanglement Just Got "Big"

The "big" news of the week so far is the two papers published in nature that increased the size of entities that can be in an quantum entanglement.

It looks like we've approached the size of a human hair, which, by any quantum mechanical standards, is humongous.

This is beginning to approach the the scale size of the Schrodinger Cat. Well, not quite, but it is in the right direction. The Schrodinger Cat-type states, which is more of a demonstration of quantum superposition (and a vital ingredient in quantum entanglement), is also getting to be huge.

Zz.

Thursday, April 26, 2018

MinutePhysics Special Relativity Chapter 4

If you missed Chapter 3, check it out here.

Here's the next chapter in MinutePhysics lessons in Special Relativity.



Zz.