Wednesday, March 23, 2016

Hey Bill Nye, Please stop talking nonsense about quantum mechanics.

Bill Nye, also known as The Science Guy, is a popular science communicator in the USA. He has appeared regularly on TV and, together with Corey Powell, produced two books. On Twitter, he has gathered 2.8 million followers, by which he ranks somewhere between Brian Cox and Neil deGrasse Tyson. This morning, a video of Bill Nye explaining quantum entanglement was pointed out to me:



The video seems to be part of a series in which he answers questions from his fans. Here we have a young man by name Tom from Western Australia calling in. The transcript starts as follows:
Tom: Hi, Bill. Tom, from Western Australia. If quantum entanglement or quantum spookiness can allow us to transmit information instantaneously, that is faster than the speed of light, how do you think this could, dare I say it, change the world?

Bill Nye: Tom, I love you man. Thanks for the tip of the hat there, the turn of phrase. Will quantum entanglement change the world? If this turns out to be a real thing, well, or if we can take advantage of it, it seems to me the first thing that will change is computing. We’ll be able to make computers that work extraordinarily fast. But it carries with it, for me, this belief that we’ll be able to go back in time; that we’ll be able to harness energy somehow from black holes and other astrophysical phenomenon that we observe in the cosmos but not so readily here on earth. We’ll see. Tom, in Western Australia, maybe you’ll be the physicist that figures quantum entanglement out at its next level and create practical applications. But for now, I’m not counting on it to change the world.
I thought I must have slept through Easter and it’s already April 1st. I replayed this like 5 times. But it didn’t get any better. So what else can I do but take to my blog in the futile attempt to bring sanity back to earth?

Dear Tom,

This is an interesting question which allows one to engage in some lovely science fiction speculation, but first let us be clear that quantum entanglement does not allow to transmit information faster than the speed of light. Entanglement is a non-local correlation that enforces particles to share properties, potentially over long distances. But there is no way to send information through this link because the particles are quantum mechanical and their properties are randomly distributed.

Quantum entanglement is a real thing, we know this already. This has been demonstrated in countless experiments, and while multi-particle correlations are an active research area, the basic phenomenon is well-understood. But entanglement does not imply a spooky “action” at a distance – this is a misleading historical phrase which lives on in science communication just because it has a nice ring to it. Nothing ever acts between the entangled particles – they are merely correlated. That entanglement might allow faster-than-light communication was a confusion in the 1950s, but it’s long been understood that quantum mechanics is perfectly compatible with Einstein’s theory of Special Relativity in which information cannot be transmitted faster than the speed of light.

No, it really can’t. Sorry about that. Yes, I too would love to send messages to the other side of the universe without having to wait some billion years for a reply. But for all we presently know about the laws of nature, it’s not possible.

Entanglement is the relevant ingredient in building quantum computers, and these could indeed dramatically speed up information processing and storage capacities, hence the effort that is being made to build one. But this has nothing to do with exchanging information faster than light, it merely relies on the number of different states that quantum particles can be brought into, which is huge compared to those of normal computers. (Which also work only thanks to quantum mechanics, but normal computers don’t use quantum states for information processing.)

Now let us forget about the real world for a moment, and imagine what we could do if it was possible to send information faster than the speed of light, even though this is to our best present knowledge not possible. Maybe this is what your question really was?

The short answer is that you are likely to screw up reality altogether. Once you can send information faster than the speed of light, you can also send it back in time. If you can send information back in time, you can create inconsistent histories, that is, you can create various different pasts, a problem commonly known as “grandfather paradox:” What happens if you travel back in time and kill your grandpa? Will Marty McFly be born if he doesn’t get his mom to dance with his dad? Exactly this problem.

Multiple histories, or quantum mechanical parallel worlds, are a commonly used scenario in the science fiction literature and movie industry, and they make for some mind-bending fun. For a critical take on how these ideas hold up to real science, I can recommend Xaq Rzetelny’s awesome article “Trek at 50: The quest for a unifying theory of time travel in Star Trek.

I have no fucking clue what Bill thinks this has to do with harnessing energy from black holes, but I hope this won’t discourage you from signing up for a physics degree.

Dear Bill,

Every day I get emails from people who want to convince me that they have found a way to create a wormhole, harness vacuum energy, travel back in time, or that they know how to connect the conscious mind with the quantum, whatever that means. They often argue with quotes from papers or textbooks which they have badly misunderstood. But they no longer have to do this. Now they can quote Bill The Science Guy who said that quantum entanglement would allow us to harness energy from black holes and to travel back in time.

Maybe you were joking and I didn’t get it. But if it’s a joke, let me tell you that nobody in my newsfeed seems to have found it funny.

Seriously, man, fix that. Sincerely,

B.

37 comments:

Brian Clegg said...

That’s just weird, isn’t it? He is getting quite old - perhaps he had a senior moment…

I have also observed that there’s a certain tendency to losing it in the media in the US - the reboot of Cosmos repeatedly dropped accuracy for drama, and a couple of times when I’ve been on a radio show with Michio Kaku, his speculative side tends to come to the fore to an extent that overwhelms the scientific content.

Sabine Hossenfelder said...

Yes maybe. But this video wasn't a live recording. It's a very carefully cut and edited recording. You'd think he should have someone looking at this before telling several million people that quantum entanglement will let us harness energy from black holes.

Good thing I don't watch TV, so I can't tell you what nonsense airs over here ;)

Uncle Al said...

Build a few hectares (intensity) L4- and L5-located (resolution) interferometric microwave telescope to image the Big Bang before the Epoch of Reionization, redshift z = 1089. Observation instantaneously defaults the entire universe into a single determined course. Meanwhile, Bill Nye must wear eyeglasses with one lens vertically and the other lens horizontally linearly polarized, randomly switching.

Choosing two different heights in Earth's gravitational potential (e.g., ground vs. geosynchronous orbit) breaks time homogeneity and Noetherian conservation of mass-energy. Extract all the energy you want, Bill.

kneemo said...

And alas, there is also ER=EPR. So the wormhole-entanglement connection isn't too outlandish.

Sabine Hossenfelder said...

(buries head in hands)

Glen Mark Martin said...

I should point out that FTL travel or communications won't allow information transfer into one's own past light cone, although it might make someone else's past light cone accessible (depending upon the relative velocities of the two parties). Even instantaneous transfers only result in a horizontal line on a space-time diagram. (Of course, that's just looking at it from the perspective of SR. If you want to play games with Einstein-Rosen bridges in GR, then things get funky.)

Sabine Hossenfelder said...

Glen,

Yes, that's right. I wrote about this in more detail here.

Noa Drake said...

The trouble is, that to some extent, people like being entertained, and are not always longing for the simple and rather dry and unspectacular truth. The marketeer feeds the people and the people feed the marketeer. It has nothing to do with science whatsoever, in my personnel opinion.

Frederico Xavier said...

Wtf did I just read

Pfogle said...

Dear Bee,

I totally support that you call out crap. The world is interesting enough without the bullshit!

I don't know how to get people to be interested in science - unfortunately, I don't have a lot of hope.

I live with two people, we are all quiet elderly now (I get a pension). One is fanatical about sport, the other is fanatical about politics. I have no interest in the first, some in the second, but I am totally confounded by their complete ignorance and lack of interest in anything mathematical. It seems you either get it, or you don't. If you don't, you just want to be entertained. 'Popular' science is a different world, and has nothing to do with science.

StrangeRep said...

I sure hope Chuck Lorre gives you (Sabine) a cameo role in The Big Bang Theory sometime soon.
Plotline: Bill Nye returns to reprise his earlier appearance and starts talking rubbish. An apparition of SH suddenly appears, clad in black leather, and proceeds to give Bill a thorough spanking... :-)

christopher said...

I was a fan of fifties science fiction when it was contemporary literature and I was in third grade. This blending of science and fiction and yearning for big future changes was a popular surge in the culture after WWII and the atom bomb made a future like that depicted in science fiction seem big time accessible. This popular expansion in science fiction also is part of what led into the space race, though Sputnik is commonly thought of as the source.

With all this in the background it seems obvious that both science and fiction would be hard to separate. Nye probably grew up like I did, reading science fiction all the time. I lived just around the corner from Glenn Seaborg in Berkeley in the early fifties. I am retired from a woood products and food processing designer career. I very well know the difference between hard and doable science and its fiction. That has never stopped me from yearning for an FTL drive and visits from our alien brothers bringing membership in the Galactic Union to us.

Pfogle said...

@StrangeRep: we've already seen the high heels!

@Christopher: I was too, back then; especially Ray Bradbury. But now, according to my 'real world' friends, I lack either the 'sporting gene' or the 'appreciates stories' gene .

It's not just QM, or multiverses; Darwin is equally misunderstood! Not to mention climate science, the list goes on...

naivetheorist said...

Bill Nye is one of the 'go to' people for a 'scientific' opinion by the american political left even though he lacks both the academic credentials and the the scientific training of a scientist. he is part of an ongoing effort in the U.S. to demonize the american political right for being anti-science (as if it's impossible to simultaneously, and without contradiction, favor free market or Libertarian politics and be a competent scientist). thus, he divides the various views on climate control into just two groups - those who believe in climate change (and human-based climate control) and those who don't (the so-called climate deniers) without acknowledging a third view which is that while climate does change, attempts by humans to modify or alter climate change is misguided because it ignores the 'law of unintended consequences'. which has been well-supported historically by various failed attempts to 'modify nature' such as the introduction of a predator species into an ecological system or the altering of the course of a river (you can also see this depicted in the recent movie "Snowpiercer" which is summarized in the IMDb as follows: "Set in a future where a failed climate-change experiment kills all life on the planet). in general, it is ridiculous to expect americans to have sensible views on ANY scientific issue (or any other issue, including politics) when 42% of the american population believes in creationism.

Noa Drake said...

Here is the link to youtube on Bill answering the question.

https://www.youtube.com/watch?v=r4oBd07pLuE

wereatheist said...

Bill Nye is one of the 'go to' people for a 'scientific' opinion by the american political left
That's why PZ Myers critizised him recently, for talking BS about genetics.

Paul Collins said...

Well, it was exciting for a while. After I learned from Dr. Nye that we might get faster-than-light telecom, plus cheap electricity from mini-black holes generated (ha ha) by the Large Hadron Collider, I thought, “I’ll jump the curve, and save a bundle!”
I sold my big supply of postage-paid envelopes at a steep discount on EBay, along with my cellphone, and planned to cancel my ISP, electric-power, and phone services. Why linger with old tech when phenomenal new stuff’s imminent? I even changed my will to leave my entire estate (basically my 1994 Saturn and credit-card debt) to The Science Guy.
That might have been a bit hasty; it appears that you and others have reservations about Bill’s video. Guess I’ll keep my computer a while longer; after all, how many megaflops do I need for text documents?
I wished I hadn’t taken such a hit on the postage—but then I realized: I can fix that! I’ll just step back a little in time and undo the sale.
Technical question: if I go far enough to prevent my birth, would it be suicide?—I mean, could my kids still collect on my life insurance? Just asking….
Anyways, all’s well then ends up that way, eh, hoser?

Euphonium said...

Shakespeare's plays had a "dumb play" to provide the abstract of the play to be performed for those whose attention span was limited.
This is the value of Bill Nye's take on science.
He is a mild light in the sea of folly and outright stupidity: The Chairman of the House Committee on Science, Space, and Technology believes that Darwin's view of evolution is not valid; that the climate is the result of god and the sun, and has nothing to do with man; and that the NOAA and the EPA are dangerous collections of insanity, lies and the devil. And those ARE views shared by a significant portion of the sitting congress, and many whose voice is carried by TV and Radio stations.
So, yes: Nye's statements about black holes and entanglement are WRONG, but in the scheme of things, even a dim candle offers a bit of light, and should not be extinguished because it is dim.

naivetheorist said...

@paulcollins said " if I go far enough to prevent my birth, would it be suicide?". Model worried about the same thing after he solved Einstein's field equations in 1949 (General Relativity and Gravitation, Vol. 32, No. 7, 2000).

naivetheorist said...

@Euphonium .. reading in dim light may not do lastingdamage to your eyes; but it often results in eye fatigue and a headache.

piein skee said...

"Entanglement is a non-local correlation that enforces particles to share properties, potentially over long distances."

I thought the issue was when the entangled particles become correlated.

The 'hidden variable' interpretation held that the correlation occurs as part of the entanglement event (hence no superluminal information is passed due to the particles being in the same place)

The Copenhagen interpretation held that there is nothing prior to measurement, hence correlation must occur with the observation event (hence superluminal information is passed due to the particles being displaced from eachother)

I think the Copenhagen interpretation has recently won this decades long disagreement.


But superluminal signalling does occur...that was the decades long question, that - apparently - has recently been settled.

It's not clear what position you are expressing. You're right that no benefit can be gleaned from this superluminal information but there has never been a suggestion otherwise.

Steve Colyer said...

Between Bill Nye and Neil deGrasse Tyson's misunderstanding of biological reproduction this was a bad week for scientific outreach. Tyson tried to defend his indefensible position because his personality is such that he won't admit to being wrong. It will be interesting to see how Nye responds. Tyson is a former galactic astronomer and not a planetary scientist, yet as the curator of the Hayden Planetarium these past 20 years he felt the need to de-Planet Pluto in 2000. He was wrong on Pluto, and now wrong on Sex. Nye graduated with a Mechanical Engineering degree in 1977 then worked on avionics for Boeing. We mechanical engineers do learn as undergrads about quantum mechanics (but not quantum field theory nor black hole thermodynamics), and we learn about special and general relativity. I am not sure if mechanical engineers learn about quantum entanglement today, but we surely didn't have formal education on the subject in the 1970's. Seth Lloyd, a physicist, heads up the quantum computing project at M.I.T.'s department of mechanical engineering. Nye should obviously be better self-taught on the subject, or consult the experts before responding, his mis-understanding of the field is embarrassingly huge. What price ego? These men are well compensated for popularizing science, and they are popular themselves. I hope Nye responds in better fashion than Tyson.

Mark said...

How about this experiment:
I believe it is possible to detect whether a set of particles is in an entangled state or definitive state (with one particle it may not be possible easily). So, if you always send e.g. packets of 100 particles in regular intervals and for one stream do a measurement of the set to encode in binary (e.g. first 100 particles not measured = 0, next 100 particles measured = 1 etc.), then the other party should be able to determine, whether that packet is still in an entangled state or in a definitive state already, so you should be able to communicate over longer distances instantaneously. So where is the error here?

Shaun said...

Well said.

piein skee said...

I've listened to his piece, and I'm struggling to find a problem. Not that's special to him anyway. He speculates fairly wild and loose, but he clearly labels that he does so, at the outset, for example of superluminal signalling he qualifies everthing he's about to say with "if we can harness it".

It would be difficult to interpret that choice of words other than confirming the FTL signalling he's talking about is between the particles in the event correlation occurs with measurement, and that he understands that there is no known way to harness this superluminality.

What's wrong with that? The time travel he introduces as personal testimony with "for me...[backward time-travel is most poignant]"

What's wrong with that? This blog speculates and adds personal testimony, why shouldn't he? He properly labels upfront the quality of his coming statements. Which cannot be said of many others. Not sure here.

piein skee said...

"whether that packet is still in an entangled state or in a definitive state already, so you should be able to communicate over longer distances instantaneously. So where is the error here?"

It's a good effort and a great way to learn.

Suggestion: It's better to assume there is something you're overlooking. Insights will come more readily with things arranged like that.

I'm no expert but FWIW nothing is different if the next packet of 100 are measured or unmeasured. Likewise, when the other party makes it's measurements, there's no way to tell which packets were measured by you and which weren't. Everything is the same.

Sabine Hossenfelder said...

Mark,

The other party can't determine this, it's as simple. Try it, you'll notice.

Sabine Hossenfelder said...

piein,

"Will quantum entanglement change the world? If this turns out to be a real thing..."

If the "this" in the second sentence does not refer to "entanglement" it's an extremely misleading formulation. If it does, it's wrong. And either way, Tom didn't learn anything. Best,

B.

Sabine Hossenfelder said...

piein,

Regarding your earlier question, you are confusing the measurement with the correlation in the entangled particles. Nothing what I wrote here refers to the measurement process. I was referring to entanglement. There is no superluminal 'action' in entangled particles, and there is no superluminal signalling of anything with anything. Best,

B.

Nick M. said...

Hi Sabine,

You won't believe who has become your latest fan boy:

http://motls.blogspot.com/2016/03/hey-bill-nye-please-stop-talking.html

Well it is the Easter season, and miracles do happen, right? ;)

-Nick

piein skee said...

"Regarding your earlier question, you are confusing the measurement with the correlation in the entangled particles."

The measurement has to be included in the specific context that we have, because the question of whether FTL exchanges occur, translates to the question of whether everything is set at the moment of entanglement.

As a [relevant] aside, could you possibly clarify whether that is your view. Where do you believe the correlation creates (in the end-to-end entanglement, if you like 'life-cycle')? Your position - I think - is only consistent with the 'hidden-variable' stance, in which everything is determined in the instant of entanglement when both particles are in the same place.

If that is your view, that would explain Lubos Motl's ovation, as he does believe that everything is settled at the instant of entanglement.

Leaving aside whether he/you are correct, you'll obviously be aware of the opposing stance, which is that the correlation does not exist until the measurement: the 'Copenhagen' view.

That's why measurement must be brought in, just to construct the superluminality 'question'.

The salient point-of-order here is that the Copenhagen view has now been proven, I believe. Do you reject the basis of this development?

The concepts of Entanglement, measurement, local/non-local, converge to indivisibility when the context becomes the speed of light in the sense we have.

I noticed you describe the entangled arrangement as a "non-local correlation" - a concept that does not involve superluminality. But non-locality is definitively superluminal. It's when something at a distance, instantaneously influences something else.

If it influences at the speed of light, it's local. If it influences slower than the speed of light, it's local.

Suggestion: Give your knowledge a 40,000 miles service. Talk to the entanglement experimentalists.

Uncle Al said...

LuboŇ°' refuses to empirically constrain his maths to create science. Bee embraces the Herculean (Brynhildran?) task of creating maths from observation. I demand that physics test spacetime geometry with geometry rather than only composition, field, and spin. A three-legged stool can be stable on any surface.

A vast hot air industry blows through the sciences as Social Justice vacuums up all gain and merit while demanding they are merely subjective (Social Justice Accounts Receivable). Is Feudalism still despicable given 80 IQ surfs?

Sabine Hossenfelder said...

piein,

Your question is totally irrelevant for the point in question. There is nothing measurable ever exchanged faster than light, that's what I'm saying. My pov, since you ask, is that it doesn't matter what I "believe" - I regard this to be a totally unscientific question. If you have a question whose answer depends on someone's believes, it's not a scientific question.

I don't personally subscribe to the Copenhagen interpretation. But for the purposes of this blog I stick with Copenhagen, unless explicitly stated otherwise. It strikes me as counterproductive for science communication to falsely give people the impression that physicist have problems with quantum mechanics. As they say, you have to learn the rules before you can break them. If everybody understands what's the difference between entanglement and superposition, I'll be happy to move on and discuss different interpretations. Don't think it's going to happen in my lifetime though. That is to say, if you seek a blog that discusses different interpretations of qm, this isn't it.

Best,

B.

JimV said...

Mr.Nye's answer was very bad, but I can think of a charitable interpretation:

Maybe he was trying to debunk the question's premise in a very polite, conciliatory, very oblique way, by saying, well if you believe that (that = quantum entanglement may someday be understood on a much deeper level which allows the transmittal of data superluminally), then we'll also be able to travel backwards in time and milk energy from black holes, "but for now, I’m not counting on it."

I would have answered something like, "No, as far as we know, quantum entanglement does not (and never will) allow us to transmit data faster than the speed of light." But I have noticed that my "something is wrong on the Internet" attitude often provokes annoyance in people although I am not trying to offend them, and maybe Mr. Nye wants to to avoid annoying his viewers. Of course by not flatly telling them when they are wrong he may confuse them - and us.

LuboŇ° Motl said...

Piein skee, you wrote:

"If that is your view, that would explain Lubos Motl's ovation, as he does believe that everything is settled at the instant of entanglement. Leaving aside whether he/you are correct, you'll obviously be aware of the opposing stance, which is that the correlation does not exist until the measurement: the 'Copenhagen' view."

Indeed, my ovation occurred because Sabine wrote something that makes sense. But every other single association you make is wrong, upside down. First, everyone who was allowed to work in Bohr's Copenhagen institute would agree that the later observed correlation is already settled (decided) at the moment when the two subsystems interacted. This is not a matter of a belief. It is an unequivocal theoretical consequence of quantum mechanics as we know it; and it is also an experimental fact that can be and has been straightforwardly verified.

The individual results e.g. for 2 entangled spins are random and the random generator is only "launched" at the moment of the observation. But if the entangled state of 2 spins implies a perfect correlation between some measurements, if some "statement about correlated properties" is e.g. known to be 100% certain, then this certainty existed long before the measurement and one doesn't need any additional "mechanisms" or "signals" to guarantee this certainty. When quantum mechanics predicts that a coming future measurement will have some property (e.g. correlation) with 100% certainty, this fact is simply determined in advance. And it is a consequence of the interaction of the subsystems in the past, e.g. the common birth of 2 electrons from a spin-0 bound state.

As Sabine - and everyone else who is sane in these respects - has also said, there is no transfer of information that would exceed the speed of light in the vacuum. Ever. It's not there and it's not needed. Any such transfer would violate the special theory of relativity.

There are no hidden variables, either, and you're completely wrong that I endorse anything about the hidden variable ideas. I don't endorse anything of the sort. There are just no hidden variables. If the randomness of results were a result of hidden variables, the laws of physics would fundamentally be deterministic (and one would indeed need some superluminal influence for these hidden variables to be compatible with the observed correlation). But they are not deterministic. The laws of physics are intrinsically probabilistic and the randomness is fundamental and can't be "reduced" to anything more fundamental.

Guillaume Verdon said...
This comment has been removed by the author.
Unknown said...

Entanglement can now be used to imply a spooky “action” at a distance:

http://phys.org/news/2015-11-nist-team-spooky-action-distance.html