Category Archives: Einstein

Late Wave

It took only one scientist to predict them but a thousand to get them confirmed (1004 to be precise). I guess if the confirmation of gravitational waves couldn't draw me out of my blogging hiatus nothing could, although I am obviously catching a very late wave. The advantage of this - I can compile and link to all the best content that has already been written on the topic.

Of course this latest spectacular confirmation will unfortunately not change the mind of those quixotic individuals who devote themselves to fight the "wrongness" of all of Einstein's work (I once had the misfortune of encountering the maker of this abysmal movie. Safe to say I had more meaningful conversations talking to Jehovah Witnesses).

But given the track record of science news journalism, what are the chances that this may be a fluke similar to the BICEP news that turned out to be far less solid than originally reported? Or another repeat of the faster than light neutrino measurements?

The beauty of a direct experimental measurement as performed by LIGO, is that the uncertainty can be calculated statistically. Since this is a “5-sigma” event, this means the signal is real with a 99.9999% probability. The graph at the bottom shows that what has been measured matches a theoretically expected signal from a black hole merger so closely that the similarity is immediately compelling even for a non-scientists.

But more importantly, unlike faster than light neutrinos, we have every reason to believe that gravitational waves exist. There is no new physics required, and the phenomenon is strictly classical, in the sense that General Relativity produces a classical field equation that unlike Quantum Mechanics adheres to physical realism. That is why this discovery does nothing to advance the search for a unification of gravity with the other three forces. The importance of this discovery lies somewhere else, but is no less profound. Sabine Hossenfelder says it best:

Hundreds of millions of years ago, a primitive form of life crawled out of the water on planet Earth and opened their eyes to see, for the first time, the light of the stars. Detecting gravitational waves is a momentous event just like this – it’s the first time we can receive signals that were previously entirely hidden from us, revealing an entirely new layer of reality.

The importance of this really can't be overstated.  The universe is a big place and we keep encountering mysterious observations. There is of course the enduring puzzle of dark matter, lesser known may be the fast radio bursts first observed in 2007 that are believed to be the highest energy events known to modern astronomy.  Until recently it was believed that some one-off cataclysmic events were the underlying cause, but all these theories had to be thrown out when it was recently observed that these signals can repeat.  (The Canadian researcher who published on this recently received the highest Canadian science award, and the CBC has a nice interview with her).

We are a long way off from having good spatial resolution with the current LIGO setup. The next logical step is of course to simply drastically increase the scale of the device, and when it comes to Laser interferometry this can be done on a much grander scale then with other experimental set-ups (e.g. accelerators).  The eLISA space based gravitational wave detector project is well underway. And I wouldn't yet count out advanced quantum interferometry as a means to drastically improve the achievable resolution, even if they couldn't beat LIGO to the punch.

After all, it was advanced interferometry that had been driving the hunt for gravitational waves for many decades. One of its pioneers, Heinz Billing, was determined to bring about and witness their discovery, reportedly stating that he refused to die before the discovery was made.  The universe was kind to him, so at age 101 he is still around and got his wish.

LIGO signal
LIGO measurement of gravitational waves. Shows the gravitational wave signals received by the LIGO instruments at Hanford, Washington (left) and Livingston, Louisiana (right) and comparisons of these signals to the signals expected due to a black hole merger event.

Progressing from the God Particle to the Gay Particle

… and other physics and QC news

The ‘god particle’, aka the Higgs boson, received a lot of attention, not that this wasn’t warranted, but I can’t help but suspect that the justification of the CERN budget is partly to blame for the media frenzy.  The gay particle, on the other hand, is no less spectacular - especially since its theoretical prediction by far pre-dates the Higgs boson.  Of course, what has been discovered is, yet again, not a real particle but ‘only’ a pseudo particle similar to the magnetic monopol that has been touted recently.  And as usual, most pop-science write-ups fail entirely to remark on this rather fundamental aspect (apparently the journalists don’t want to bother their audience with these boring details). In case you want to get a more complete picture this colloquium paper gives you an in-depth overview.

On the other hand, a pseudo particle quantum excitation in a 2d superconductor is exactly what the doctor ordered for topological quantum computing, a field that has seen tremendous theoretical progress as it has been generously sponsored by Microsoft. This research entirely hinges on employing these anyon pseudoparticles as a hardware resource, because they have the fantastic property of allowing for inherently decoherence-resistant qubits.  This is as if theoretical computer science would have started writing the first operating system in the roaring twenties of the last century, long before there was a computer or even a transistor, theorizing that a band gap in doped semiconductors should make it possible to build one. If this analogy was to hold, we’d now be at the stage where a band gap has been demonstrated for the first time.  So here's to hoping this means we may see the first anyon-based qubit within the decade.

In the here and now of quantum computing, D-Wave merrily stays the course despite the recent Google bombshell news.  It has been reported that they now have 12 machines operational, used in a hosted manner by their strategic partners (such as 1Qbit).  They also continue to add staff from other superconducting outfits i.e. recently Bill Blake left Cray to join the company as VP of R&D.

Last but not least, if you are interested in physics you would have to live under a rock not to have heard about the sensational news that numerical calculations presumably proofed that black holes cannot form and hence do not exist.  Sabine Hossenfelder nicely deconstructs this.  The long and short of it is that this argument has been going on for a long time, that the equations employed in this research has some counter-intuitive properties, and that the mass integral employed is not all that well-motivated.

Einstein would have been happy if this pans out, after all this research claims to succeed where he failed, but the critical reception of this numerical model has just begun. It may very well be torn apart like an unlucky astronaut in a strongly in-homogeneous gravitational field.

This concludes another quick round-up post. I am traveling this week and couldn't make the time for a longer article, but I should find my way back to a more regular posting schedule next week.

Lies, Damned Lies, and Quantum Statistics?

Statistics has a bad reputation, and has had for a long time, as demonstrated by Mark Twain's famous quote[1] that I paraphrased to use as the title of this blog post. Of course physics is supposed to be above the fudging of statistical numbers to make a point.  Well, on second thought, theoretical physics should be above fudging (in the experimental branch, things are not so clear cut).

Statistical physics is strictly about employing all mathematically sound methods to deal with uncertainty. This program turned out to be incredibly powerful, and gave a solid foundation to the thermodynamic laws.  The latter were empirically derived previously, but only really started to make sense once statistical mechanics came into its own, and temperature was understood to be due to the Brownian motion. Incidentally, this was also the field that first attracted a young Einstein's attention. Among all his other accomplishments, his paper on the matter that finally settled the debate if atoms were for real or just a useful model is often overlooked. (It is mindboggling that within a short span 0f just 40 years ('05-'45) science went from completely accepting the reality of atoms, to splitting them and unleashing nuclear destruction).

Having early on cut his teeth on statistical mechanics, it shouldn't come as a surprise that Einstein's last great contribution to physics went back to this field. And it all started with fudging the numbers, in a far remote place, one that Einstein had probably never even heard of.

In the city that is now the capital of Bangladesh, a brilliant but entirely unknown scholar named Satyendra Nath Bose made a mistake when trying to demonstrate to his students that the contemporary theory of radiation was inadequate and contradicted experimental evidence.  It was a trivial mistake, simply a matter of not counting correctly. What added insult to injury, it led to a result that was in accordance with the the correct electromagnetic radiation spectrum. A lesser person may have just erased the blackboard and dismissed the class, but Bose realized that there was some deeper truth lurking beneath the seemingly trivial oversight.

What Bose stumbled upon was a new way of counting quantum particles.  Conventionally, if you have two particles that can only take on two states, you can model them as you would the probabilities for a coin toss. Lets say you toss two coins at the same time; the following table shows the possible outcomes:

    Coin 1
     Head  Tail
 Coin 2  Head  HH  HT
   Tail  TH  TT

It is immediate obvious that if you throw two coins the combination head-head will have a likelihood of one in four.  But if you have the kind of "quantum coins" that Bose stumbled upon then nature behaves rather different.  Nature does not distinguish between the states tails-head and head-tails i.e. the two states marked green in the table.  Rather it just treats these two states as one and the same.

In the quantum domain nature plays the ultimate shell game. If these shells were bosons the universe would not allow you to notice if they switch places.

This means, rather than four possible outcomes in the quantum world, we only have three, and the probability for them is evenly spread, i.e. assigning a one-third chance to our heads-heads quantum coin toss.

Bose found out the hard way that if you try to publish something that completely goes against the  conventional wisdom, and you have to go through a peer review process, your chances of having your paper accepted are almost nil (some things never change).

That's where Einstein came into the picture.  Bose penned a very respectful letter to Einstein, who at the time was already the most famous scientist of all time, and well on his way to becoming a pop icon (think Lady Gaga of Science).  Yet, against all odds, Einstein read his paper and immediately recognized its merits.  The rest is history.

In his subsequent paper on Quantum Theory of Ideal Monoatomic Gases, Einstein clearly delineated these new statistics, and highlighted the contrast to the classical one that produces unphysical results in the form of an ultraviolet catastrophe. He then applied it to the ideal gas model, uncovering a new quantum state of matter that would only become apparent at extremely low temperatures.

His audacious work set the state for the discovery of yet another fundamental quantum statistic that governs fermions, and set experimental physics on the track to achieving ever lower temperature records in order to find the elusive Bose-Einstein condensate.

This in turn gave additional motivation to the development of better particle traps and laser cooling. Key technologies that are still at the heart of the NIST quantum simulator.

All because of one lousy counting mistake ...

[1] Actually the source of the quote is somewhat murky - yet clearly inducted into popular culture thanks to Twain  (h/t to my fact checking commenters).

UPDATE: For some reason Because this site got slashdotted new comments are currently not showing up in my heavily customized WordPress installation – I get to see them in the admin view and can approve them but they are still missing here.

My apologies to everybody who took the time to write a comment! Like most bloggers I love comments so I’ll try to get this fixed ASAP.

 

For the time being, if you want to leave a comment please just use the associated slashdot story.

The comment functionality has been restored.

The Greatest Tragic Hero of Physics

Although widely admired and loved, in the end he died like so many who came to extremes of fame or fortune - estranged from family and separated from old friends. The only person to witness his death in exile was a nurse, incapable of understanding his last words which were uttered in a language foreign to her.

If his private life was a template for a telenovella, viewers would regard it as too over the top: As a teenager his parents leave him with relatives to complete school - they need to resettle to a foreign country. He rebels, his school teachers give up on him, he drops out. He travels across the Alps to reunite with his family. If it isn't for the unwavering support of his mother he would probably never move on to obtain a higher education. She manages to find him a place with relatives in a country of his native language so that he can finally gain his diploma. The same year he renounces his old citizenship and also quits the religion of his parents.

He subsequently enrolls in a prestigious university, but ignores the career choice that his parents had in mind for him. He falls in love with a beautiful fellow student from a far away land. His parents are against the relationship, and so are hers. Against the will of their families they want to get married, but our hero struggles to find a job after graduation. He hopes to be hired as an assistant at his university, just like the rest of his peers, but he has once again fallen out with some of his teachers. Many of the other members of the faculty only notice him because he skips so many lectures - especially the purely mathematical ones. Still, he passes all the tests, relying on his friends' lecture notes.

His future wife-to-be becomes pregnant out of wedlock, has to return to her family and gives birth to a little girl with Down syndrome. He never even gets to see the girl. This summer - two years after graduation - with the help of a friend, he finally lands his first steady job. Later that year his father dies, and shortly after that our man marries his beloved Mileva.

Meet the Einsteins:

Images of old Albert Einstein are so iconic that some people tend to forget that he wasn

Having settled down in Bern he now manages to find the discipline and inner calm for his subsequent groundbreaking works. I can not even begin to fathom how he musters the strength to do so, coping with a full time day job and a young family. Discussing his ideas with friends and colleagues certainly helps and surely he must discuss his research with Mileva as well (how much she influenced his work has been somewhat of a controversy). The following three years, even while working as a patent clerk, are the most fruitful of Albert Einstein's life. His research culminates in four publications in the year 1905 that irreversibly change the very foundation of physics. His papers ....

  1. ... describe  for the first time the theory of Special Relativity.
  2. ... show the equivalence of mass and energy i.e. the most famous E=mc².
  3. ... propose the idea of energy quanta (i.e. photons) to explain the photoelectric effect.
  4. ... demonstrate that Brownian motion is a thermal phenomenon.

Without the realization that mass and energy are equivalent (2), there'd be no nuclear energy and weapons. Without Einstein's energy quanta hypothesis (3), there'd be no quantum mechanics, and his work that explains the Brownian motion (4) settled, once and for all, the question if atoms were real.  At the same time, it provides the missing statistical underpinning for thermodynamics.

These were all amazing accomplishments in their own right, but nothing so resonated with the public as the consequences of Einstein's theory of Special Relativity (1). This one was regarded as a direct affront to common sense and achieved such notoriety that it was later abused by Nazi propaganda to agitate against "Jewish physics".

Already, at this time, physics was such a specialized trade that usually the man on the street would have no motivation to form an opinion on some physics paper. So what caused all this negative attention? Einstein's trouble was that by taking Maxwell's theory of Electrodynamics seriously he uncovered properties of something that everybody thought they intuitively understood. Any early 20th century equivalent to Joe the Plumber would have felt comfortable explaining how to measure the size of a space and how to measure time - they were understood as absolute immutable dimensions in which life played out. Only they cannot be if Maxwell's equations were right, and the speed of light was a constant in all frames of reference. This fact was really hiding in plain sight, and you don't need any mathematics to understand it - you only need the willingness to entertain the possibility that the unthinkable might be true.

In 1923 an elaborate movie was produced that tried to explain Special Relativity to a broad audience. It turned out to be a blockbuster, but still didn't convince the skeptical public - watching it made me wonder if that is where so many misconceptions about Einstein's theories started. It does not contain any falsehoods, but it spends way too much time on elaborating relativity, while the consequences of the invariability of light speed are mixed in with results from General Relativity, and neither are really explained. Apparently the creators of this old movie felt that they had to start with the most basic principles and couldn't really expect their audience to follow some of Einstein's arguments. Granted, this was before anybody even knew what our planet looked like from space, and the imagined astronaut of this flick is shot into space with a canon as the preferred mode of transportation - as, for instance, imagined by Jules Verne. Nowadays this task is much easier in comparison. You can expect a blog reader to be desensitized by decades of SciFi. Also, having a plethora of educational videos at your fingertips makes for a straightforward illustration of some of the immediate outcomes of accepting light speed to be constant in all frames of reference.

For a modern audience, a thought experiment containing two spaceships traveling in parallel with a setup that has a laser signal being transferred between them requires little explanation. All that is necessary to come to grips with, is what it means that this laser signal travels at the same speed in all frames of reference. For instance, this short video does an excellent job explaining that an observer passing by these spaceships will have to conclude that the clocks for the space pilots must go slower.

Nevertheless, even nowadays you still get publications like this one, where two Stanford professors of psychology perpetuate this popular falsehood in the very first sentence of their long monograph:

[Einstein] established the subjective nature of the physical phenomenon of time.

Of course he did no such thing.  He described how the flow of time and the temporal ordering of events transforms between different inertial reference frames as an objective physical reality.

Over a hundred years special relativity has withstood all experimental tests (including the recent faster than light neutrino dust-up).  Yet, public education has still not caught up to it.

This is the second installment of my irregular biographical physics series intended to answer the question of how physics became so strange. Given Einstein's importance I will revisit his lasting legacy in a future post.
 

The Rise of the Quantum Hippies

... and why I blame Niels Bohr.

A satirical hyperbolic polemic

Recently there was a bit of a tempest in a teapot in the LinkedIn quantum physics group because it is very much over-run by members who I dub "Quantum Hippies".  I.e. the kind of people who think they’ve read a quantum mechanics book after putting down Capra’s the Tao of Physics – you have probably encountered the type.

So this begs the question: Where did they spring from?

It certainly didn’t start with Capra, he was just a catalyst.

I blame this guy:

Niels Bohr stands accused.

If it wasn’t for him, and his side-kick Heisenberg, Bohr’s Copenhagen Interpretation would have never become the kind of dogma that it did.  We are still suffering the consequences.

Science is a competitive sport, even more so in the olden days when the myth of the lone genius reigned supreme.  Most of the founding fathers of quantum mechanics lacked many things but not ego. Much has been written about the struggle between Bohr and Einstein. The latter of course never stood a chance as he has been far removed from the development of the new theory. It didn’t help that he was old at the time and easily painted as a relic. Other challengers to the Copenhagen Interpretation were dealt with in various ways.

  • It was helpful that David Bohm could be vilified as a communist and nobody listened to de Broglie anyway.
  • Schrödinger mocked the new dogma with his famous cat in a box thought experiment but did not have it in him to put up a real fight.
  • Max Planck fell into the same geezer category as Einstein, but was even easier to dismiss due to his far less prominent name recognition.
  • Karl Popper was “just a philosopher”.
  • Others like Landé weren’t much of a challenge, falling into the “Landé who?” category.

Hence the Copenhagen Interpretation reigned supreme, and much energy was now devoted to keep its dirty little secret tucked away, in the closet, under the stairs with the key thrown away.

Maybe some of the energy directed at defending it against the other interpretations was in part motivated by the thought that it’ll be easier to keep this problematic aspect of the new theory under wraps. For whatever reason, Bohr and Heisenberg gave birth to a new physics omertà, the “shut-up and calculate” doctrine.  This would have far reaching consequences - way beyond the realm of physics.

The raison d'être of the hippie revolution was to challenge authority (that arguably was asking for it).

What a delightful gift Bohr had prepared for a counter-culture movement that was already high on half-understood Asian influenced mysticism and other more regulated substances. And so the Copenhagen Interpretation’s dirty little secret was dragged out of the closet and subsequently prostituted.  I am of course referring to the fact that the wave-collapse originally invented by Heisenberg requires an observer or observing mind. This was subsequently bastardized into the idea that “the conscious mind creates reality”. Just as Einstein’s Special and General Relativity entered popular culture as the spectacularly wrong premise that "everything is relative”,  cart blanche for magical thinking was brought to you courtesy of some of the greatest minds of the 20th century.  A more spectacular blow‑back is hard to imagine.

This was super-charged by Bell’s theorem that confirmed quantum mechanics’ essential non-locality.  This in turn was translated as the mystical certainty that “everything is instantaneously connected all the time”.  And so to this day you get spectacularly wrong pop science articles like this one. It completely ignores that these days entangled qbits (the essential ingredient in the thought experiment on which this article hinges) are very well understood as a quantum information resource, and that they cannot facilitate an instantaneous connection between distant events.  The term “instantaneous” has no absolute meaning when Special Relativity is taken into account. This is especially egregious when contemplating that this was published in the American Association of Physics Teacher’s journal.

Although it’s a well-established fact that the public American education system has hit rock bottom in the developed world I still would have expected better.

The Flower Power movement has been generally associated with the left political spectrum but it is in the nature of such powerful memes to eventually permeate the entire mainstream thinking.  Hence American journalists prescribe to a “he said she said” school of journalistic “objectivity”, after all everything’s relative, and so political operatives of all color feel fully justified in subscribing to a “Triumph of the Will” line of thinking.

When Ron Suskind interviewed inside staff from the Bush Jr. administration and questioned them as to how they thought they could just remake Iraq with the limited resources committed, the staffer famously answered: “… when we act, we create our own reality”.

Yes, I blame Niels Bohr for that too.