The Physics Police

The Physics Police

Monday, May 16, 2016

Minute Physics hasn't solved the grandfather paradox

I like the channel Minute Physics a lot. Their videos tend to contain quick physics lessons which are fun and accessible to a lay audience. However, I was greatly disappointed by their latest video called Solution to the Grandfather Paradox which unfortunately contains pure pseudoscience in place of the advertised solution.

The video starts off with a great description of the Grandfather Paradox. In short, this paradox arises if you go back in time to kill your grandfather. Being quite dead, he never has grandchildren and so you were never born. This leads to a logical contradiction: if you were never born, who killed your grandfather?

The video goes on to propose a solution whereby you kill your grandfather in an alternate timeline, so he wasn't really your grandfather to begin with. But this solution is summarily dismissed.
"But that's boring because it just avoids the paradox." (0:34)
Fair enough. There's plenty of published work in the scientific literature on this topic that doesn't involve alternate timelines. Surely they're going to get to that science stuff, right? Wrong.
"I'm showing this as a linear series of events but really it’s two entangled histories happening in parallel." (1:02)
I don't know what it means for two histories to be "entangled" or to happen in "parallel". Here the video shows a Mobius strip with a timeline drawn on it, following the plight of our time traveler.

Mobius strip following actions to their logical consequences.
This shows a chain of causality which loops back on itself. This is a clever way of depicting the paradox but it doesn't "resolve" anything. It merely shows the circular reasoning which caused us to call this a paradox in the first place. This particular type of circular reasoning is called an infinite regress, and is generally considered illogical in science and philosophy.

This mistake is able to slip by due to selective inattention. Viewers are easily distracted by the pleasant visual stimulation (myself included, on first watching). As we try to follow along the Mobius strip with our eyes, we don't notice the false conclusion. This "argument from cool shapes" is something I'd expect from Spirit Science, but not from Minute Physics, which I've always taken as a serious science channel.

Next, to make this glaring fallacy more palatable, we're served a steaming pile of quantum woo-woo. Would you like physics jargon on the word salad? Just say when...
"Subatomic particles regularly do multiple different things in parallel – it’s called quantum superposition ... if the universe were to exist in a superposition of two states – your grandfather is alive and your grandfather is dead – then the natural result is a superposition of two states: you’re born and able to go back in time to kill your grandfather, and you’re not born. And the natural result of these is a superposition of two states – your grandfather is dead and your grandfather is alive – and so, at least from a logical perspective, this looping timeline is entirely consistent and there’s no paradox." (1:11)
When! When!

Let's notice the equivocation between the "parallel" lengths of paper in the Mobius strip and the use of the word with regard to subatomic particles being in different states at the same time. The implication is that what's true about the quantum world applies to our time traveler. This does not logically follow because people are macroscopic objects relatively unaffected by quantum effects like superposition due to decoherence.

Don't get me wrong. I'm cool with describing the quantum state of large objects, even the entire universe as in the Many Worlds interpretation of quantum mechanics. The problem is the superposition shown in the video makes no sense at all and doesn't show what it's claimed to show.

Sure it's science, see the math symbols? That makes it science!
We're told these states represent a model of the entire universe. I'll call this left-most state where your grandfather is alive |A>. We know this state has some representation of your grandfather being born. We can evolve it into the future to see him grow up, put on a bowler hat, marry, have son or daughter, etc. Keep evolving the model forward and eventually our time traveler is born, puts on a red hat, travels through a wormhole or whatever, and emerges on the other side to kill his own grandfather.

See the problem? We can't fully describe |A> without also including |B> in there, too. Because they aren't different possible states of the universe. They're all events in one and the same history! A history that's self-contradictory. Using math symbols from quantum mechanics doesn't make this problem go away.

Now, there's nothing wrong with trying to use the idea of superposition to solve the Grandfather Paradox. But to prematurely claim victory having done no work and having explained nothing is inexcusably poor physics. Which is sad, because many fascinating papers have been published on this topic. The three million Minute Physics subscribers could have learned about the foundational work done by David Deutsch, Seth Lloyd, and others.

Next the viewer is presented with a very telling tease.
"And a similar paradox-free solution can be obtained by viewing the problem as a steady-state solution to a Markov chain ..." (1:48)
When! When! Aside from the obvious attempt to stupefy the audience with big words, Minute Physics seems to have misinterpreted a quantum computing exercise for theoretical physics. In the comments section they cite a lecture and paper by Scott Aaronson. The lecture includes discussion of the Grandfather Paradox "in a computational form" which indeed uses a Markov chain.

This is not a resolution of the paradox per se, but a computer model which satisfies some of its properties. It's not part of any an actual scientific theory. It's just a toy model to teach computer science. Aaronson imposes upon this model the requirement that Deutsch calls "causal consistency". But that's boring because it just avoids the paradox! And it has nothing to do with quantum superposition. Because, as we've seen, quantum superposition can't solve the paradox.

So, having mentioned real science only once, teasingly, the video concludes with this moral lesson.
"The main point is sometimes we think a situation creates a paradox when it doesn’t, and really the only paradox is how our thinking can be twisted enough to dream up time-traveling murderous grandsons, but not twisted enough to think about twisting time." (2:09)
That's ironic because the only paradox is how such a terrible script got on Minute Physics.

Monday, March 7, 2016

Star Trek transporters aren't suicide machines

I really like the YouTube channel CGP Grey. But his latest video The Trouble with Transporters contains some rather serious philosophical and metaphysical mistakes.

The thesis of the video is that the Star Trek transporter technology is a silent holocaust (1:45).
"...your experience of stepping into the transporter will be a funny sound, a bright light, then nothingness eternal, while down on the planet a brand new life complete with all your memories up to the moment before your death popped into existence..." (1:20)
This description is some combination of scientifically false and philosophically bankrupt.

The video seems to be asking us to accept metaphysical Dualism in which consciousness cannot be fully explained as the result of processes in the body and in particular the brain. There is not one shred of scientific evidence to support metaphysical Dualism. There is a mountain of evidence to the contrary. That mountain is called "neurology".

Dualism comes from a pre-scientific time and originates in the religious idea of an immortal soul. It's falsehood is the consensus view in all relevant sciences (neurology, psychology, philosophy, etc.). It is a supernatural proposition and so by definition irreconcilable with the scientific method.

The video grants that the transported body experiences no discontinuity in biological activity. Not in any tissue or organ. Since the brain is an organ, it too experiences no discontinuity in its function. Since consciousness is nothing more than a description of part of the the function of the human brain, the transported person experiences no discontinuity in consciousness.

It's really that simple.

And we don't even need fictional technology to see this in action. Our body is made of cells, which in turn are made of atoms, and on down until you get to the particles from the Standard Model. In particular, the matter particles i.e. quarks and leptons. (Yes, here comes the requisite physics.)

Even these fundamental particles aren't permanent objects.

Matter is not made of permanent objects having unique identities.

For example, there's no unique history of a particular electron. Electrons are fungible excitation in the electron field. In Quantum Mechanics, we predict the behavior of particles according to laws which include consideration for an infinite number of interactions which would create and destroy the particle in question from one moment to the next.

There is quite simply no philosophical justification for the absolute persistence of any physical object given appreciation for this lesson from the study of matter at the smallest scale. So there is no justification to say that I am absolutely persistent as a physical entity, just sitting in my chair.

The Star Trek transporter is an unnecessary addition to the thought experiment because modern physics already forces us to confront the exact problem this video raises.

But the video brings up the "problem of consciousness" and insists there's something "unmeasurably different" between the pre-transport and post-transport copies of a person (3:46). Now, there is something importantly different. Location in space! But that's entirely measurable. And it suffices to describe everything different about the histories of the pre-transport and post-transport person as physical objects. The problem of consciousness never enters into it.

The video even goes so far as to call the transporter a "suicide box" (3:33) which it obviously is not. Suicide is the act of intentionally causing one's own death. Death is the end of the life of a person. The life of someone who goes through the transporter does not end. Sure, transporter errors can cause their life to end. So can car rides.

Star Trek transporter errors can also apparently duplicate a person. This raises interesting questions, like which is the "real" person, but even then nobody dies. So no one committed suicide. So it's not a suicide box. Tom Riker wasn't forced to commit suicide.

Finally, and most ridiculously, the video claims it's "impossible to know" whether you are the same person as the person who you were when you went to bed least night (5:00). This is some combination of false and bullshit because all healthy people act as if they are the same person day to day, and treat others the same way. Any definition of personhood that claims otherwise is inconsistent with reality and therefore a complete and total bullshit.

Redefining words to fit an otherwise comically false narrative is classic pseudophilosophy. I never expected such poor content from this otherwise great channel.

Thursday, February 4, 2016

No, Zika wasn't patented by the Rockefeller Foundation

Conspiracy theorists have been buzzing since a possible link between the mosquito-spread Zika virus and microcephaly became big news.

One particularly laughable conspiracy theory is that the virus has spread in Brazil due to GM mosquito testing in the same area.

First of all, there's no plausible mechanism by which GM mosquito experiments could have caused the Zika outbreak. On the contrary, both GM mosquito testing and mosquito-borne viral outbreak probably share the same underlying cause: the plague of mosquitoes endemic to the general region! The whole point of the GM mosquito program is to combat mosquito-borne contagious diseases like malaria, dengue, and now also Zika. To accuse it of spreading the virus is a particularly dangerous and ugly irony.

Second, the claim that Zika spread from the area where GM mosquitoes had been tested is false. True, both events happened in Brazil, but it's untrue to say they share an epicenter.

Another vicious conspiracy theory is that the virus was patented by The Rockefeller Foundation. This is, if you'll pardon the pun, patently false. Instead of the actual patent application readers are shown a screenshot from a website that sells research samples of the isolated virus online. Under the product's history, we see:
"Name of Depositor: J. Casals, Rockefeller Foundation"
All this means is that the sample was provided by the famous virologist Jordi Casals-Ariet. He discovered the Lassa virus. And he's exactly the person we'd expect to be studying the Zika virus, which is known as an "arboviruses" because it's spread by mosquitoes. Here is a quote from an interview.
"So by the mid 40s you had applied the compliment fixation test to arboviruses, and you had applied the suckling mouse to replication of arboviruses. So you were preparing really, without knowing it, to do a large amount of work in terms of growing viruses, making antigens, and preparing viruses."
The man's a hero. Thanks to work by people like him we have vaccines for many deadly viruses.

What about the Rockefeller Foundation? In 1952 Casals joined the Rockefeller Foundation and worked in a lab where he helped identify viruses sent in from research stations all around the world. Here's another clip from the same interview with Casals.
"We were in New York at the time, at the Rockefeller Institute of Medical Research where our laboratories, the Rockefeller Foundation, was located. We were the reference, or the clearing house, for all the field laboratories. We were supposed to help them, both by doing tests for them, and at the same time, developing better procedures if necessary, so they could use them."
The "Rockefeller Foundation" is literally the name he called the lab where he worked! The only conspiracy here is doctors and researchers around the world conspiring to learn about deadly viruses in order to better treat human epidemics.

Two of the authors on the paper reporting discovery of the Zika virus have "The Rockefeller Foundation" as their author affiliation. Private funding of basic science has played a vital role in human health.

But why are Zika virus samples sold online? It's common practice for medical research supplies to be sold online. Importantly, the sale is regulated by the CDC. Zika, for example, is Biosafety level 2. Unless you work for a lab that meets these regulations, you won't be able to complete your purchase of Zika.