BC DATA SCIENCE
Saved by @zmbnski

On Bayesianism, the Many Worlds Interpretation, and personal identity.

Some thoughts worked out in a letter to a friend, which is the kind of thing you do when off Twitter for a glorious week. (🧵)

 “Chance is ignorance”—the Bayesian story; all probabilities represent states of mind, not states of the world. One *could* put (some) chances “in the world”, but let’s take Occam’s Razor seriously...
That the probability of a fair coin coming up heads is 50% simply means that marginalizing (tracing, as the physicists say) over the hidden facts leaves you, nearly, maximally ignorant of the outcome.
Quantum uncertainty (access below!) poses an apparent challenge to this story. There seems to be nothing to be ignorant about when it comes to (say) electron spin—there is nothing “inside” the object.
https://t.co/DhHmN0ndjx
The electron is a simple object, in other words. So where does the uncertainty come from? One could follow David Wallace’s wonderful interpretation in terms of chaotic dynamics and decoherence, but let’s see if we can take another route...
It lies, finally, not in our lack of knowledge of what’s inside the electron (there is nothing there), but rather a lack of self-knowledge—we do not know which branch of the Universe we ended up in!
We lack knowledge, in other words, of the referent of a pronoun—which “I” I am. If you’re Saul Kripke, the rigid designator has detached—you must be re-baptized. For that reason, we should naturally refer to MWI as Born Again Quantum Theory (with the obvious pun).
The world is constantly forking, of course, but the vast majority of those forks are completely meaningless to us; they fall, for all intents and purposes, into the same equivalence class.
It’s only in rare cases (like those electrons at ANU) that we come directly into contact with these forks, where the equivalence class splits. Most classical uncertainty is simply further refining knowledge about the initial quantum state.
(I won’t tell you how my ANU quantum coin came up—ha ha! I know which branch we’re on, you don’t, but that’s just a classical, Bayesian matter.)
This is probably super-obvious to someone like @seanmcarroll, but there are two nice things about it.
First, it’s a nice way to get at the MWI from an unexpected direction. You don’t have to know about the Schrödinger Equation, decoherence, etc to realize the Universe *must* split.
That might help (depending on your philosophy of science) increase your confidence in the underlying metaphysical claims.
Second, it helps me understand why The Universe Splitter is a non-trivial device. It really does split universes... https://t.co/Uar00s1zmN
And it’s kind of cool to realize that it wasn’t until we learned to isolate and pay attention to quantum effects that the universes began to split!
Definitely a (classical) fact of the matter! The radioactive decay couples very quickly to the classical world—which means you’ve already split before you have time to wonder about his state. https://t.co/ffFcngLV3a
In any case, nearly all the forks that matter in human history happened long ago (at inflation, or perhaps reheating). I think. Can anyone think of a pre-twentieth century coupling to novel quantum uncertainty?
Most quantum effects are invisible to us—meaning that our ignorance of which universe we’re in is permanent, and therefore irrelevant. Perhaps when it comes to single-photon events—@DavidDeutschOxf’s frog in _Fabric of Reality_...
But did any decision, or memory, ever hang on the outcome on how a single photon interfered with itself? (Until today, when we basically, being humans, do it for the lulz!)
I’m a little worried I’m missing some massively obvious quantum influence, but one point in my favor is that this kind of world-splitting re-baptism took so long to discover. It’s not obvious at all.
And technically, we couldn’t know about it until Bell’s Inequality proved that there were no (relevant) hidden gears within the electron.
YES! I think this is meaningful. https://t.co/bKiU3y0cAX
It’s (nearly) all classical uncertainty. Those worlds exist, but are separated by a vast gulf—they split billions of years ago, well before any decision we might make.
Until someone uses the ANU device to hang some history on. There’s even a kind of odd utilitarian morality to it—if you are thinking about doing something bad, and hang it off ANU, you reduce the harm by a factor of two.
Nearly all personal identity splits happened (literal) eons ago. Laplace’s demon—we’re just discovering the consequences of the (decohered) initial conditions. https://t.co/pXX0YHIVJy
Those Universes separated so long ago that there’s no real sense in which Classical Simon1 and Classical Simon2 are comparable. You might as well line me up with Alpha Centauri Simon.
Nothing actually forks it. We’re emergent phenomena, our experiences equivalence classes over quantum states. ANU just happens (for the lulz) to split them, which I’m suggesting is actually super-rare in human history. https://t.co/hJ47tyaGIN
Definitely. My lamp tips over. That informs me about a sequence of classical events that goes back to the formation of the Earth, and much further. Now I know which path the atoms took after initial decoherence, but that was my ignorance. https://t.co/ig89rZCbcQ
Kripke semantics would say that a copy of the standard meter doesn’t have to “know” it’s not the standard meter for it to be distinct. https://t.co/Y6EzUTtgtP
This also helps me understand all those bits that ANU gathers but never serves to users. They (eventually) vanish (deleted for space), leaving no trace. Nobody will ever know how they turned out, and so our equivalence class can’t split.
Just realized that one source of universe-splitting started happening with (I think) cosmic ray errors in silicon. Where, in particular, the ray interacts is a quantum effect—causing one error over another, becoming visible to the operator.
You have to buy the Kripke story about how pronouns work. I, personally, think it’s intuitive and how I use them—but you may not! https://t.co/w5kHRVIc4K
I don’t know! I have Meillassoux on my desk (_After Finitude_) and would love any suggestions. https://t.co/JyY1yQsmzF
Oh, I think this works, yes. Sad, but true. Any happier examples? (Although in another sense, Max’s example *is* happy—there are yous that survive.) https://t.co/hErcyUtJ66

More from Simon DeDeo

Simon DeDeo
Simon DeDeo
@SimonDeDeo
Donna Strickland, one of this year's Nobel Laureates, was not considered "notable enough" for Wikipedia as late as this May—reported by a number of sites, including the Independent. I dug into this a little. Here's the data—


This is the first deletion, back in 2014. A bit hard to read between the lines, but the basic story that an admin had Stickland's page "speedy deleted"—i.e., deleted without debate. The method was something called Copyright Jujitsu.

In particular, the admin had the page deleted not because of notability, but because it included a photograph of Strickland that had ambiguous copyright status. This is a method that people developed to get rid of content they didn't want, but also didn't want to debate.

"Copyright Jujitsu" because it is usually used against spam from companies; a PR officer uploads promotional material to Wikipedia. Instead of debating whether it's neutral, the admin can say "we'd love to have it, but the material appears to violate your company's copyright".

Usually the PR office and the IP office are separate in a company, and the idea of releasing promotional material under public domain is such a legal nightmare that the PR person goes away.
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Simon DeDeo
Simon DeDeo
@SimonDeDeo
Someone tosses a coin ten times; it comes up heads every time. What's the probability it comes up heads on the next toss? (Pretty darn high—part of @nntaleb's work is unprogramming you from your high-school rules of thumb.) Now consider the (related) Gambler's fallacy...

In this case, it's a theory about compensation: the worse one's luck is, the more likely it is to see a reversal. On the surface, it's irrational. The more bad luck you have, the more you accumulate evidence that the system is rigged.

But there's also an anthropic component. If the luck is bad enough, it starts to become inconsistent with your survival. You've accumulated evidence for correlations in the environment, but these correlations (may be) inconsistent with (people like you) being in this environment.

An example. You're in a city where everyone takes public transport. You encounter a string of bad delays. It's reasonable to conclude they'll end—otherwise people wouldn't take public transport. It's unlikely that you happened to show up right when the network collapses.

Of course, that's a bad heuristic in a casino, which relies on a constant influx of losers. But in other environments, particularly with persistent populations and no evidence for sudden changes in the underlying laws, it makes sense.
CRYPTO
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Simon DeDeo
Simon DeDeo
@SimonDeDeo
So, today, for the first time in 25 (!) years of Apple, I downgraded. From the 2016 MacBook Pro to my 2013, which I had kept in a drawer...


It was pretty simple to do—Apple Time Machine backups let me do it with one click.

That first tweet captures, in two pictures, how badly Apple has “lost the plot” (to quote @wylieprof). On the right is the Apple MagSafe adapter, from 2013. On the left, what I had “upgraded” to.

Thanks, Apple! I really was nostalgic for worrying about yanking my computer off the table.

Oh and I really appreciated not knowing if my computer was charging. What was great was the little whoop sound you used, so that the speaker before me could be informed I was charging my laptop.
TECH
Simon DeDeo
Simon DeDeo
@SimonDeDeo
One thing that goes unremarked about Wikipedia: the vast majority of the content was written over 12 years ago—which means (given turnover) that the editors dominant today were not directly involved in that creation.

Put another way, the editors who built the dominant nodes in this network...


...have little overlap with the ones who made this much more recent managerial flowchart.


Internet time runs at hundred-fold speed—the difference between the people who painted what's in the Uffizi, and the people in charge of keeping those paintings from deteriorating. Very different tasks, and (one presumes) very personalities as well. @PaulSkallas?
ALL
Simon DeDeo
Simon DeDeo
@SimonDeDeo
"I lied about my basic beliefs in order to keep a prestigious job. Now that it will be zero-cost to me, I have a few things to say."


We know that elite institutions like the one Flier was in (partial) charge of rely on irrelevant status markers like private school education, whiteness, legacy, and ability to charm an old white guy at an interview.

Harvard's discriminatory policies are becoming increasingly well known, across the political spectrum (see, e.g., the recent lawsuit on discrimination against East Asian applications.)

It's refreshing to hear a senior administrator admits to personally opposing policies that attempt to remedy these basic flaws. These are flaws that harm his institution's ability to do cutting-edge research and to serve the public.

Harvard is being eclipsed by institutions that have different ideas about how to run a 21st Century institution. Stanford, for one; the UC system; the "public Ivys".
LIFE

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Data Professor
Data Professor
@thedataprof
Cheat sheet that summarizes #DataScience in 10 pages
(Links in the comments below 👇)


2/ Link to the cheatsheet by Maverick
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Sophie Hill
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@sophie_e_hill
This is a more wonky thread about how I made this visualization in #Rstats using the awesome visNetwork

First step is to create the underlying network data. We need one file of "nodes" - i.e. the people and organizations. And one file of "edges" - i.e. the connections between them.

I created these by hand, based on excellent investigate journalism:


Now we can pull these together to create a network visualization!

You'll notice that I included a column for "type" in the nodes file. This allows me to use different icons for people vs firms vs political organizations.


All the icons are taken from @fontawesome. I *think* the visNetwork 📦 currently only works with fontawesome version 4.7, which is a bit limited – e.g. I decided to use a book icon to represent the fringe Evangelical Christian sect "Exclusive Brethren"! 😂


I very much enjoyed getting to use the "incognito" icon to represent all the unknown donors that have funded Tory MP Owen Paterson's overseas jaunts!
DATA SCIENCE
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John Myles White
John Myles White
@johnmyleswhite
This post is pretty bizarre, but it manages to hit on so many false beliefs that I've seen hurt junior data scientists that it deserves some explicit

(1) The notion that R is well-suited to "building web applications" seems totally out of left field. I don't feel like most R loyalists think this is a good idea, but it's worth calling out that no normal company will be glad you wrote your entire web app in R.

(2) It is true that Python had some issues historically with the 2-to-3 transition, but it's not such a big deal these days. On the flip side, I have found interesting R code that doesn't run in modern R interpreters because of changes in core operations (e.g. assignment syntax).

(3) "Most of the time we only need a latest, working interpreter with the latest packages to run the code" -- this is where things get real and reveal some things that hurt data scientists. If this sentence is true, it's likely because you don't share code with coworkers.

(3) Really is a broader issue in data science: people only think of what they need to do their work if no one else existed and code was never maintained. Junior data scientists almost always operate on projects they start from scratch and don't have to maintain for long.
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Maria Khalusova
Maria Khalusova
@mariaKhalusova
To my JVM friends looking to explore Machine Learning techniques - you don’t necessarily have to learn Python to do that. There are libraries you can use from the comfort of your JVM environment. 🧵👇

https://t.co/EwwOzgfDca : Deep Learning framework in Java that supports the whole cycle: from data loading and preprocessing to building and tuning a variety deep learning networks.

https://t.co/J4qMzPAZ6u Framework for defining machine learning models, including feature generation and transformations, as directed acyclic graphs (DAGs).

https://t.co/9IgKkSxPCq a machine learning library in Java that provides multi-class classification, regression, clustering, anomaly detection and multi-label classification.

https://t.co/EAqn2YngIE : TensorFlow Java API (experimental)
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Greg Yang
Greg Yang
@TheGregYang
1/ A ∞-wide NN of *any architecture* is a Gaussian process (GP) at init. The NN in fact evolves linearly in function space under SGD, so is a GP at *any time* during training. https://t.co/v1b6kndqCk With Tensor Programs, we can calculate this time-evolving GP w/o trainin any NN


2/ In this gif, narrow relu networks have high probability of initializing near the 0 function (because of relu) and getting stuck. This causes the function distribution to become multi-modal over time. However, for wide relu networks this is not an issue.

3/ This time-evolving GP depends on two kernels: the kernel describing the GP at init, and the kernel describing the linear evolution of this GP. The former is the NNGP kernel, and the latter is the Neural Tangent Kernel (NTK).

4/ Once we have these two kernels, we can derive the GP mean and covariance at any time t via straightforward linear algebra.


5/ So it remains to calculate the NNGP kernel and NT kernel for any given architecture. The first is described in https://t.co/cFWfNC5ALC and in this thread
DATA SCIENCE

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👇 Thread. New deck getting published this week: "Consumer startups are awesome, and here's what I'm looking to invest in at Andreessen Horowitz." If you want to read it, subscribe to my newsletter here: https://t.co/262t8eh0wf


1/ A lot of new consumer technologies have been introduced to US households in the last 100 years. But it's taken many of them - like the telephone - more than 50 years to get to the majority of the US. Why is that?


2/ We had to literally teach people how to use phone. Which end goes to your mouth, which goes to your ear. Say "hello" when people call. The motivation of consumers to talk to their friends has always been there, but we had to teach the behavior


3/ If you compare phones to the latest technologies, there's been a huge shift. Things are being picked up much faster.


4/ Even while there's been all this innovation recently, physically speaking, we are still the same human beings from 100,000 years ago.
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1/ So here is a thread on how I turned $32,000 into $1.2m and back to pretty much zero (once taxes are paid).

Just note, I am not bitter or salty in any way at all, the last 2 years have been an amazing ride - travelled the world, been wealthy, been poor.

2/ Dec '16, my advertising agency folded, I had a little bit of money left and I put $32k into Bitcoin and Ether. As it started to go up I diversified into everything, Monero, Dash, this that, any crap - even Ripplecoin. Everything just kept going up.

3/ By March I think I had around $300k and $500k by the summer. I used to take 25% out but towards the end of the summer I got greedy and put it all back in and by December it was $1.2m.

4/ Thinking I was an absolute genius I decided to start a bunch of businesses. As silly as it sounds I had this goal of making $5m as I wanted to buy Bedford Town Football Club and get them in the league, and as Crypto was going up forever I needed 6 months.

5/ So:
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Yes - all of the above as a one-man army :)
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XVIII Airborne Corps🐉...
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1 of 16: WE ARE ALL JEWS HERE: THE STORY OF RODDIE EDMONDS

One of the most moving and relevant stories of the Battle of the Bulge, or any American Soldier in any war, is that of Master Sergeant Roddie Edmonds, a Knoxville, Tennessee native, who served with the 106th Infantry.


2 of 16:

Roddie was captured early on in the Battle of the Bulge, on December 19th, when Panzer forces plowed through his unit.

He, along with almost his entire regiment, was forced to surrender.


3 of 16:

The men were transported to the Stalag IX-A POW camp in Ziegenhain, Germany.

Roddie was the senior enlisted American Soldier at the site. As such, he was the conduit between all American Soldiers and their German captors.


4 of 16:

In late January, the camp’s commandant, Major Siegmann [pictured here], ordered Roddie, a Christian, to identify all Jewish Soldiers and order them to stand in formation by themselves the next day.

[Jewish Soldiers were a minority within American units]


5 of 16:

Throughout WWII, captured Jewish Soldiers were often tortured and then killed by their German captors.

In fact, Jewish Soldiers had been told to bury their dog tags before capture. The dog tag identified Jews with the letter “H” for Hebrew.
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MASTER THREAD on Short Strangles.

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• Positional Strangles
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• Position Sizing
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• Plenty of Examples
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How to sell Strangles in weekly expiry as explained by boss himself. @Mitesh_Engr

• When to sell
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Beautiful explanation on positional option selling by @Mitesh_Engr
Sir on how to sell low premium strangles yourself without paying anyone. This is a free mini course in


1st Live example of managing a strangle by Mitesh Sir. @Mitesh_Engr

• Sold Strangles 20% cap used
• Added 20% cap more when in profit
• Booked profitable leg and rolled up
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2nd example by @Mitesh_Engr Sir on converting a directional trade into strangles. Option Sellers can use this for consistent profit.

• Identified a reversal and sold puts

• Puts decayed a lot

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"How the Avengers would respond to the Capitol riot" (a thread)

CAPTAIN AMERICA - tells Falcon, "I fought Nazis once before. They're extremely dangerous." They then see the guy scaling the Capitol wall fall into the shrubs. Falcon: "You sure these are the same Nazis?"

IRON MAN - lands by the guy carrying the podium. Says, "Mind if I borrow this?" then tosses it to Hulk, who swings it like a bat at the mob. Guy: "Hey, that's MY podium!" Iron Man: "Actually it's the Speaker's. And technically, it's a lectern." Then punches him through a wall.

BLACK WIDOW - enters hotel room where Jack Dorsey is tied up. Rips duct tape off his mouth. Jack: "I'll do anything you want!" BW: "Disable POTUS's Twitter. NOW!" Jack fumbles with his phone. "Done. Anything else?" BW: "Yeah. Trim your beard for God's sake." *tosses him clippers*

HULK - grabs a selfie stick from one of the guys and beats him over the head with it. Deeming it too small, he grabs another guy's Confederate flag and takes out a whole swath of rioters. He then tosses the flag to Cap, who uses it as a javelin to impale a fleeing Ted Cruz.

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