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Wednesday, January 17, 2018

A few questions about basic physics

Here are a few questions I have about physics after reading (or attempting to read) several books.I can't seem to find consistent answers to these. I don't have the base of understanding necessary to ask good questions yet, but I hope most of these questions are at least interesting!

(Apologies for typos! My voice recognition seems to insist that molecules are "made up of Adams"...)

Section 1: About general relativity:

One of the starting example situations that often seem to be used in general relativity is this idea of someone who is traveling on a train or other moving base, who shines one light forward in the direction they're traveling and another light backward. 


There are two targets that are equally distant from them on the train, in the forward direction and backward direction. If a rider on the train turns both lights on at the same time, naturally the rider perceives the lights hitting those targets at the same time.


But if there is an observer who is stationary on the ground outside the train, watching the train pass them by, then because the speed of light will be absolute relative to them, the light can't be traveling forward at the speed of the train *plus* the speed of light. Here's where standard explanations say something like "To our outside observer the beams will be going at a different speed relative to the train than what the rider sees." The outside observer will observe the light hitting the backward target first, which in these examples is supposed to demonstrate the weird implications of the absolute speed of light relative to any observer.


There are a lot of different assumptions here that aren't being addressed, which I don't understand. First of all, the example above seems to mix subjective experience and objective descriptions of reality. What does it mean to say that "to" the outside observer, the light hits the backward target first? The outside observer doesn't have magic, objective-time goggles that can instantly communicate when the light hits a target. 


But they can see when the light that hit the target bounces to them and strikes their eye or camera or whatever. All they can do is receive reflected light. 


But suppose it *was* possible for light to travel faster than the official speed of light. That would mean it would be possible for there to be one objective reality between the two observers: the light is moving forward at the speed of light that the observer on the train observes, plus the forward speed of the train. The light moving backward is moving at slightly slower than the speed the observer on the train perceives. And the two targets really do got struck at the same time. But because the forward Target is farther away from the outside observer than the backward Target, the light that reflects towards the outside observer would not reach them at the same time. They would perceive the backward target to have been struck first. That's the order in which they perceived the targets to be struck by light actually does not demonstrate the absolute speed of light limit.


In this scenario, it really only depends on the relative position of the train to the outside observer when the targets are struck. If the train is moving towards the outside observer, and is relatively far away, they will see the light from the forward target first. If the train is past the outside observer, they will see the light from the backward target first.


But, dropping my counterfactual, that's the same outcome that's predicted by the general relativity example. Only in a very tiny range of starting locations for the train, almost but not quite to the position of the outside of server, do my counterfactual and general relativity differ on which target the outside observer will appear to observe first.


I ultimately Einstein is right, and I think I've argued myself back to a position of agreeing with him, but I'm just doing a ton of extra scenario building and going way past the point where I have any idea if what I'm saying is right or totally wrong. The simplified scenarios that are illustrated in example after example seem to me not to actually demonstrate the difference that general relativity predicts. Sometimes I wonder with some scenarios if, for information to return to all of the original observers, it's like it has to undo the effects of general relativity.


I read a quick explanation of the Michelson Morley mirror experiment, in which (so I've read) it was observed that light traveling in the direction that the Earth is spinning or moving around the Sun or something didn't move faster than light traveling some other direction. I'm sure I am wildly misstating this. But the way it was explained to me seemed to have nothing surprising at all. Because if the light was indeed moving at the suppose it speed of light plus the speed of the Earth, but we are ourselves moving at the speed of the Earth, how would we perceive that extra speed?


Again, I'm sure that from the perspective of someone who really understands this stuff my questions are totally misinformed, I just can't fill in that context myself with the books I have.


So my overall question is, what is a scenario in which our conventional expectations are subverted by what we observe, and we can only conclude that general relativity is correct?


Question 1: is my description of the train scenario correct?


Question 2: what is a scenario in which are conventional expectations are supported by what we observe, and we can only conclude that general relativity is correct?

Section 2:

Regarding atomic resistance to contact:


I read in several places that as electrons in different atoms (which are each magnetically balanced) approach each other, they exchange photons. That is, photons are the mechanism by which electrons communicate their proximity to each other. 


Or maybe photons are the mechanism by which atoms communicate their proximity to each other. I don't really begin to understand. 


I've read that you could think of electrons using a metaphor of two people passing a dodgeball back and forth, where they're able to do it much faster as they get closer together, which means in effect their resistance to each other is higher. And as atoms get too close, their electrons push each other away and that pushes the whole atom away. 


But another thing I've read is that atomic nuclei just really don't like to be too close together, that there's a sort of proton exclusion principle or something, and that's why two atoms don't like to be pushed together. 


The source of my question is why is it, fundamentally, that two objects don't just merge as they collide? What is changing within them as they get close together? When I stand on a floor, I understand that the floor is pushing back at me with 200 lb of force. What I'm surmising is that that force comes from the compression of the floor, whose atoms are getting pushed together more than they like, and something is happening within them that repels those atoms from each other, and repels my shoe atoms from the floor, and those atoms repel my foot atoms, Etc. But I can't figure out which law of physics is the main one that's at work here.


A related question: I've been told that water is essentially incompressible, that it doesn't shrink and heat up as you compress it the way gases do. 


But say two people are standing on top of two big plungers, where the space under the plunger for one person is filled up with water and for the other person is filled up with air. I assume that what's happening within the chamber in each case is that the material is being compressed and creating resistance that pushes back against the plunger with an equal force to the weight of the person, at least as soon as the plunger initially depresses to adjust to the person's weight. What is the source of the force in each case? 


I've been told in a gas it is the rate of Brownian motion collisions from the gas atom bumping upwards against the plunger. But I gather that's not the case with the water. If not, what is it? Are there two totally different laws operating in the two cases? Or is it more a matter of degree, where the sort of atomic explosion I've been talking about is indeed still at work in the gas and that's why gas atoms bump each other and communicate motion, and similarly there is a bit of Brownian motion in the water as well but it's just not a significant way of describing the water's resistance to compression? Is there anything relating to that electrons playing dodgeball with photons idea that makes sense here?


Question 3: why is it, fundamentally, that two objects that are pressed together don't just merge or pass through each other?

Question 4: is my description of the Brownian motion of the gas producing force correct?


Question 5: by what atomic-level mechanism is the water producing upward force against the plunger?


Question 6: what happens within a single atom as another atom (which it doesn't need in the sense of forming a molecule with it) approaches it?

Section 3:

My next question is about reflection of light. I know there are some aspects of quantum mechanics that it's foolish to expect to understand intuitively, and maybe this is one of them. From what I (shakily) understand, incoming light is being reflected by a mirror at all sorts of angles, and the only reason we perceive an angle of light shining on a mirror at 10 degrees as also reflecting off the mirror at 10 degrees (or, rather, 170 degrees) is that the average of the possible angles of the reflected light is 10 degrees. I'm sure I have said that wrong, I'm not sure if this is an issue of quantum mechanics or of the wave/particle nature of light, or both.


I'd love a good explanation of that aspect of reflection, but I'm trying to keep my questions a bit more focused. So instead, I want to ask:


Question 7: when a photon hits an object, say a speck of green paint, what happens within that within that atom that causes a photon to be sent back out? 


Question 8: in a very light absorbent substance like vantablack, what is happening when one of its atoms is struck by a photon?


Question 9: is it correct to assume that a surface a single atom thick would still, in theory, be capable of reflecting light at a complementary angle to the one the photons came in on?


Question 10: on the atomic scale, why should a photon that makes contact with the atom at one angle be sent out at the same angle?


Question 11: say you had many such single atom think surfaces, reach oriented at a different angle. You shoot a stream of photons at each one, striking each one at a single atom. How do the photon and atom know what angle to send the photon out at? Isn't the scenario identical, for all intents and purposes, for each of these atoms being struck by a photon?


About the two slit experiment, I don't understand enough to ask a good question. I guess I fundamentally don't really understand what we're talking about when we say light acts as a wave. Sometimes it seems as though the concept of it being a wave is something far beyond our ability to have an intuitive understanding of. Other times, it seems practically Newtonian and straightforward. For instance, I get that some substances are transparent to some wavelengths of light and opaque to others; and that's like a measurable thing, you can imagine AM radio waves hitting all kinds of obstacles in all there going back and forth that higher bandwidth FM waves sail past. Or with polarized filters, you can say only light that is moving back and forth along some particular rotation angle will get through. All this has given me the sense that light waves involve light photons essentially moving up and down as they travel forward, varying their position relative to the average center of their direction of travel by inches or even feet.


But this understanding doesn't seem like it can be right. Because you can't like catch a photon several inches away from the center of its vector of travel, right? Because it seems to be that would mean our eyes would have no idea where any of the photons it receives are coming from.


And then you go to the two slit experiment and suddenly we're talking about light waves not being a phenomenon centered along one direction of travel, but something where the waves are a more elusive concept than the somewhat concrete sense I get from the ease of polarization.


Anyway, I'm far from being able to articulate good questions about the two slit experiment, or even just polarization. I just know there's a lot of background that I don't understand!

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Wednesday, January 10, 2018

Infinite music hasn't been written yet

I can appreciate Radiohead's plagiarism case against Lana Del Rey (or rather, their publisher and production team's case against her publisher and production team). (Though the offer of 40% of the writing proceeds seems like a more than fair offer, considering how changed the song is AND the degree to which they likely borrowed for their original. Rejecting that and using our tax money to try to get more is disgusting.)

A friend of mine, skeptical of the series of court cases where musical writers claim ownership of similar songs, wondered "how many pleasing combinations of chords or notes can be created before everything that follows might be considered evocative or a remix of its predecessors".

But a musical composition is so much more than just a sequence of notes on paper. There are so many dimensions along which compositions can be placed: multiple instruments, voices, pacing, things which brilliant artists understand on a subconscious level but which we are a long way from even being able to formalize. It's akin to the breadth of expression possible with letters. Any order of letters seems obvious in retrospect, and billions of words are written every day, yet no one has accidentally recreated the plot of Don Quixote. I mean heck, two generations ago there are entire genres of music that had never even been imagined. There are surely hundreds more musical genres that haven't been imagined yet.

Lots of people have directly and indirectly taken inspiration from Don Quixote, much like, say, Yankee Hotel Foxtrot takes inspiration from "Revolution no. 9". But the space of possible stories isn't so crowded that anyone has written a story that accidentally also features a novel-besotted wannabe warrior leading a series of misadventures where he concocts patently false scenarios with the help of a more clear-eyed assistant in his thrall. Some people, of course, purposely write an updated DQ! That's my point: the world of stories is wide open, not crowded; accidental similarities are tenuous. When the similarity is higher, as with DQ's influence on The Idiot, City of Glass or The Moor's Last Sigh, it turns out to have been intentional.

When you hear extended musical similarity like Billy Joel vs. Beethoven, it's not an accident.

When someone has a musical innovation like, say, Teddy Riley's New Jack Swing, and it sweeps through the musical landscape, you see how much new musical composition draws from the field of existing ideas (and as opposed to coinciding with existing ideas through a sort of pigeonhole principle). You can practically see an idea like using voices as percussion in R&B sweeps its way through the memeosphere, from Bone Thugs 'n Harmony to Destiny's Child.

And much like with plagiarism in the written word, there's actually less gray area in practice than you might expect. So many turns of phrase and rhythms and patterns are borrowed from the landscape of subconscious reference, and brief deliberate copying. But then you have times that someone says the same eight words in a row that were in someone else's speech and it's 100% clear that the line was lifted altogether.

Similarly, in music there are tons and tons of times a sequence of 5 or 10 notes is going to match some existing song closely. I imagine algorithms are finding these for some clever troll as we speak! But the similarity in Lana del Rey's case goes way beyond the 40-odd notes (modulo an arpeggio or two) that match Radiohead's. The relative length of those notes, the relationship to the chords in the accompanying instrumentation, the story they tell--you'd need millions of parallel universes with no Creep before you'd get a song this similar.

It can seem strange that building specifically on others' ideas is so accepted in, say, the startup world and the world of novels, but so punished in music. Uber doesn't own anyone else's "Uber for X" (unless they get a BS patent). But think how much easier it would be to make, say, a good punk album where you just do a reworded version of a Bon Iver song here, a Cat Power song there, than to really write those songs from scratch.

The world of possible music composition isn't crowded. The world of possible stories isn't crowded. Most great music and most great stories haven't been written yet!

Don't be fooled by the relative stagnation of pop music in the last 15 years. Infinite music hasn't been written yet. More spookily, infinite music will never be written. It's not crowded in there--it's lonely!

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The communications tool I wish existed

I've daydreamed for a while about building a Swiss Army Knife messaging-management software-as-a-service.

Basically, I've been paid to develop messaging-manager software by several clients, and approached by other clients who I didn't have time to work for. They're using Sheets, Excel, Google Contacts or Salesforce, and that's all fine for storing lists of contacts, but they want to be able to track who got which email or SMS message when, how they responded, etc.

I've heard "Why can't I email all my active clients and tell them about the new website? I have them right here in Salesforce!" And, "Why can't I text all the seniors who haven't turned in their graduation requirements that they're due in 3 weeks? I have the list right here in Google Sheets!"

I'm not really sure what v1.0 would make sense for this, but I've had multiple clients swear to me that they would use it even if they had to import their contacts every single time they wanted to send a message. (It feels like I'm taking crazy pills when I hear this--surely it exists? But it doesn't, as far as I can tell... and I've tried a bunch of Mailchimp-family SaaS's to try to help them find one that works.)

What I've tried so far:

  • Salesforce: AFAIK, has no built-in ability to systematically contact the contacts; expect a GUI nightmare, or a lot of coding from scratch, if you wish to take actions like adding a field using the output of a query
  • Mailchimp: when I asked them how to maintain the information I'm gathering about communications with my Mailchimp contacts, they suggested regularly exporting them to a spreadsheet, updating columns, and re-importing the list.
  • Sendgrid: works well for what it is, which is very limited. Also, they confirmed to me that they discard your entire history each week, and won't stop doing this at any price
  • Mixmax: I'm a paying user and their customer support is great, but I find the Gmail integration janky, contact syncing inconsistent, and the various campaign configurations impenetrably confusing
My feature wishlist:
  1. Gmail: I can still use gmail as my primary email client
  2. Google Contacts: it syncs with my google contacts
  3. Google Sheets: I can point it to a google spreadsheet and it can figure out how each row connects to a contact (eg, by email, or name, or whatever)
  4. Static fields: I can add arbitrary fields to contacts, like “customer lifetime value” or “has been sent invite” and it’ll remember the values for each contact forever
  5. Tags, not lists: Instead of each list/group maintaining its own info about a given contact (as Malchimp does), the assumption is that a given contact belongs to many groups/lists/tags. Google contact groups are just treated like tags; google spreadsheet columns can also be tags, and I can create custom tags.
  6. Static tag info: each tag has its own properties, including associated “why you got this” text
  7. Exploding addressee lists: I can compose an email to thousands of people and it’ll make each one appear to have received a personal email from me, without anyone else included
  8. Safe templates: my email can use a template like "Hey there ,", and it will either let me define what to show if there is no firstname, or flag all that don’t have an obviously good entry for each field used (so there’s no awkward “Dear Mr. ,” blanks)
  9. Exploding phone number lists: I can compose a text and it’ll send to 1 number for each person
  10. Detect bounces: it’ll detect bounces from email, SMS and mark those addresses/numbers to not be used
  11. Why you got this (email): it adds “why you got this” text to bottom of email
  12. Unsubscribe (email): it adds unsubscribe text and link to bottom of email
  13. Why you got this (SMS): it adds “why you got this” text to bottom of initial SMS
  14. Unsubscribe (SMS): it adds unsubscribe text and link to initial SMS
  15. Read receipts: it has email read receipts to show me if someone read it
  16. Templates depend on medium: I can make distinct email text and sms text for the same message
  17. Failover to SMS: I can send a message once without specifying email or SMS, and it can send SMS if email is not available or bounces
  18. Salesforce: it can sync with salesforce
  19. Live Salesforce queries: tags can have associated salesforce queries that pull in a set of contacts live
  20. Process responses: I can include questions in the message, and it can store responses
  21. Response parsing: message responses are automatically processed when relevant, like “Hell no” = no, “6 out of 10? maybe 7?” = 7, “*** 1/2” = 7, etc.
  22. Saved searches: search results can be stored as a column: eg search result list for “have received 0-2 emails from me” becomes: new member == 1
  23. Live saved searches: search results can be stored as a live/self-updating column (updates after every message send or data change)
  24. Responses are a column: message responses become a column that can be used in logic, like “all people who haven’t responded or responded ambiguously or responded with a no"
  25. History lives forever: I can look up the history of communications with any recipient, I don't need to worry about storing it myself
  26. Set math: I can get a set of all contacts in various combinations of groups/tags, using logic like or, and, in B but not A, etc.

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