> Now place a candle in the middle of the room, one that shines light in every direction. As the light bounces around the different corners, will it always illuminate the whole room? Or will it miss some spots? A side effect of proving the magic wand theorem, Eskin said, is that it conclusively answers this old question.
This is a point light in the middle of a regular polygon right? Why is this noteworthy? Is it that the light settles on all points evenly? Is it in spite of some sort of phase cancellation thing?
To help people understand why this theorem is surprising, first rephrase it from “the candle lights the entire room (bar a finite number of points)” to “the candle can be seen from any position in the room (bar a finite number of positions)”
Next, don’t think of “room”; that puts your mind too much towards simple, almost convex structures. Instead, think of the a floor of a building where all doors are removed.
For example, take the ground floor plan of the Pentagon, with its myriad of rooms and corridors, with all doors removed, and replace all walls by perfect mirrors. Is there a spot to place a candle so that it or it’s reflection, reflection of a reflection, etc. can be seen from all locations in the pentagon, bar a finite number? The theorem says there is.
Now, feel free to make it harder: add back the doors, but don’t completely close them, keeping a rational angle with the walls the door opening is in. Feel free to make the angles as small as you like.
Next, place room dividers wherever you want, as long as they are perfect mirrors, form rational angles with the walls, and don’t completely close of some room or corridor in the Pentagon.
Do you think you’ll be able to completely shield of at least one room, wherever that candle is placed? If so, you’re mistaken.
That would make a great 2D game... You’re given a floor plan at each level (with increased complexity/geometry) and you need to place the candle (light source) in a point where it will illuminate the whole floor.
I find that so interesting, as if these positions are an intrinsic mathematical property of the room. I wonder if there's a classification of rooms this way. What do rooms that have the same number of dark points have in common?
This theorem also has implications in the limits of using sound and light for surveillance. The government could ban homes with irrational angles in order to guarantee there are no dark spots for any kind of radiation surveillance.
The only constraint on the polygon is that the angles are rational multiples. There all kinds of crazy non-convex shapes that satisfy this constraint, which is why the result is noteworthy.
I think this is also interesting when it comes to physics. A dark "point" physically means that the electromagnetic fields permeate the entire room except over a finite set of Dirac delta functions. If you were to try and put something physical in the dark point, you'd quickly turn this into a quantum mechanics problem. I don't think the dark points matter in real life because confining yourself to a single point would require infinite momentum.
This theorem assumes perfect mirrors and Newtonian light. In real life, I predict that the entire room would be illuminated. There's a path of least action for the light to take, but there is a probability of taking other paths. Scattering is not precise. I would think that would add a fudge factor to the paths.
>Imagine a room made out of perfect mirrors, Eskin said. It doesn't have to be a rectangle; any weird polygon will do. (Just make sure the angles of the different walls can be expressed as ratios of whole numbers. For example, 95 degrees or two-thirds of a degree would work, but pi degrees would not.)
My impression was that it did not have to be a regular polygon.
Despite the headline I don’t see anything about deleting data. Just that it won’t try to recognize you.
That being said, I went on my profile to check and it was already set to No (don’t do facial recognition). Is this the default? Or is this actually an old thing that I disabled a long time ago.
It sounds to me like a primary use case of this would be... cheating...
Unlike other dating platforms, this one is integrated with your supposedly up to date profile. Being able to set up a low risk secret crush with a known friend seems likely to be popular to those interested in doing so.
That is to say, a person who wants to cheat has no problem having a Facebook profile, so there’s not a need for anonymity against being found by known acquaintances like you might expect on other platforms.
There's no way Facebook would allow someone to use Facebook Dating while their relationship status is set to "married" or "in a relationship." That leaves only alternate accounts as an option for someone using their dating to cheat, but I dont think Facebook has much of an alternate account culture.
Unless someone has an account for personal use and an account for "work" use that they cheat with? And their work friends list are all part of the pool for the Facebook dating protocol? That would get real messy.
Yeah, this is going to break up a lot of marriages, imo. People are going to get suspicious of their spouses facebook activity in a way that they aren't currently.
There are reasonable concerns about using genetic modifications to kill things like mosquitos, but why don’t we use this tech against invasive species which we want to be absolutely removed from an ecosystem?
It would be simple to solve that with a breeding population kept isolated. If the genetic modification wipes out the wild population, you reintroduce it.
For species that reproduce quickly, such as insects, this is reasonable.
That said the mosquito trick is that we can produce drones whose babies are also only drones with the same genetic malfunction. The number of drone-only mosquitoes expands exponentially until they are most of the males, then most of the population, and then in a couple of more generations, the population is wiped out for lack of females.
I'm not sure that this would work as well for a species that moves more slowly. Or whether we know how to do the trick for species other than mosquitoes.
This is also balanced by the fact that as far as we know, most any mosquito can fill most of the same roles in the food chains. We're mostly concerned with wiping out the few species that feed on humans and our pets/livestock. We could eradicate two or three species which carry West Nile, Malaria, Zika, Chickungunya, and a few other really bad diseases of humans, dogs, cats, songbirds, horses, and cattle that are spread by mosquitoes. Other species would still lay eggs, hatch, and get eaten or reproduce normally without threat to us.
Also note that despite the technique being proven in the lab, and the fact that mosquitoes kill a half-million people per year, we have not yet pulled the trigger and done it. Exactly for fear of the potential ecological consequences.
Very anemic effort, but I think Twitter also proactively suspended 200,000 accounts as well. The operation probably pivoted following the crackdown. Still it's a little difficult reconciling how low effort this is with the Chinese influence everywhere narrative.
>The ICPC’s preliminary research indicates that the information operation targeting the Hong Kong protests, as reflected in this dataset, was relatively small hastily constructed, and relatively unsophisticated. This suggests that the operation, which Twitter has identified as linked to state-backed actors, is likely to have been a rapid response to the unanticipated size and power of the Hong Kong protests rather than a campaign planned well in advance. The unsophisticated nature of the campaign suggests a crude understanding of information operations and rudimentary tradecraft that is a long way from the skill level demonstrated by other state actors. This may be because the campaigns were outsourced to a contractor, or may reflect a lack of familiarity on the part of Chinese state-backed actors when it comes to information operations on open social media platforms such as Twitter, as opposed to the highly proficient levels of control demonstrated by the Chinese government over heavily censored platforms such as WeChat or Weibo.
I'm really curious how Twitter attributed the campaign was state backed, something Facebook and Google did not claim. Were these accounts transparently VPNing from the mainland or was there something more sophisticated happening.
It might have some downsides, but let’s not forget about the daily torture and atrocities we experienced before the government started manipulating our memories.
In this case it’s just choosing an option that involves very large numbers because it’s learned that it’s opponent can’t handle large numbers. There’s no code injection
The SMB3 ACE is one of the most technically interesting glitches. The usual skips and saves are much more mundane.
My point here is that there is similarity between (some) human players and some AI players. Even the discussion whether exploiting a glitch is actually 'winning' also looks very similar.
Anywhere, for any reason. I work remotely and could do so comfortably on the train, so what's the rush? I'd rather spend more time and have a good experience than be treated like livestock at the airport.
How does one "work comfortably on the train"? Assuming you are using a computer, or even do anything else intellectual including reading, the constant vibrations and movement of the train places a very definitive strain on the eyes (because they have to constanly work to even be able to focus on what you're looking at) and makes it harder to concentrate. Many people experience the rocking effect where they get very sleepy. The internet connection will just inevitably end up being worse and less reliable, completely off in some areas. You don't have access to a great desk, to a great chair, you are constantly distracted by noises. Dependent on what your seating arrangement is, you can be distracted by your neighbors, even if they don't talk to you. There is very little space, you can forget getting up and stretching well or taking short walks to gather your thoughts. How does any of this amount to "comfortable work"? Have you tried working on a train? It is an illusion that one could comfortably work on one. Even reading a book comfortably might be a stretch on some of them.
No transport is free of movement or vibration, cars most especially. Far more get car and air sick than train sick. So unless you're advocating never travelling at all, I'm not sure what point you're making.
From my experience of all, train is probably the most comfortable of the lot, with the best seating, most desk space - you get a proper table and even a mains point. You don't get forced to breathe dry low oxygen air, and avoid the nasty taste of road fumes.
Biggest negative is the relative cost of train compared to all the other forms of transport, which speaks more of relative subsidy than inherent costs.
The point I am making, which is clear if you read previous comments I was answering to, is that travelling for a whole day in a train is not in any way an equivalent, productivity-wise, to travelling 3 hours by plane and then working the rest of the day in an office or a home.
There might be other reasons to take trains over airplanes, but "so I can comfortably work on it" is a very questionable one.
3 hours by plane also includes 2 hours traveling to and from the airport, an hour of security queueing, and another hour of navigating the airport, boarding, and picking up your luggage. All those extra stressful hours are not available for working. Now you've spent the better part of a day traveling, just how much are you going to get done "the rest of the day"?
Get TSA Precheck, carry your luggage on (easy for work trips IME), learn the typical transit time and latencies for security. I can leave my house at 4:30-4:45 for a 6 AM flight (boarding closes at 5:45), reliably make it, have breakfast on the flight, and walk off the plane directly to ground transport and be in fine shape to work a full day somewhere.
You can add hours of buffer time if you want (if you're flying to do an organ transplant, maybe that's a good idea); most people can take a 0.5% chance of missing their flight. (I've literally never missed one, though I've been a few minutes away from doing so a couple times, usually because of my own error, once because of unexpectedly long security lines, even for TSA Pre.)
Ideally there'd be a sleeper service so I could maybe do a little work in the evening, travel overnight, have a relaxed breakfast arriving ready for a full day. To me that's miles ahead of getting up 5 hours early with all the mucking about of getting there, checkin, baggage and what not involved in air travel, and almost as ridiculous on arrival.
Personally I've never had issue working on trains, and the many friends who use trains regularly seem to do work well enough too.
I guess it's subjective, but I've always worked well on trains with a laptop--certainly better than on any other form of transportation. You usually get a full sized table in front of you, and while granted it's not an Aeron chair, I find them comfortable enough.
I haven't experienced any issues with vibration or overwhelming sleepiness and haven't ever heard anyone complain about these things.
The other passengers and background noise are no less distracting than an open plan office, and it could even be much quieter if you have a cabin with just a few other passengers.
A good reliable internet connection is crucial, I agree. I think it should be manageable with proper planning.
Lots of people walk up and down the cars on long trips. You have to walk to get to the dining car, bathroom etc. It's certainly easier and more pleasant to walk and stretch on a train than a plane or a bus.
I have tried on multiple occasions, on anything from local trains to high-speed long-distance trains. Works very well for me. The landscape passing by is very calming and helps me focus.
That is interesting actually. You could argue that the tiny amount of leave Americans typically receive contributes to emissions. With people being unable to spare additional time for travel there is a strong disincentive to use any form of transport apart from flying.
However, one could also argue that the majority of the nation does not have the luxury to spend a single day traveling, so going by sleeper train is even better. I recently had a business trip to Switzerland and took the sleeper train from Berlin to Basel (9pm to 8am) where I arrived after a nice breakfast (in the train) so much more relaxed than after a hectic flight. Its more expensive but only because its basically hotel + trip.
Right, but the equivalent of trains that take multiple days are sleeper/red-eye flights of 5+ hours during which many people can catch up on some sleep.
I've taken that train as well and while it's nice for routes of around that distance, I'm not sure how it would be beneficial if you had to sit on it for days. That wouldn't be much of a sleeper trip.
Maybe not the majority, but certainly many millions of people in all kinds of jobs could conceivably work remotely for a day or two while traveling by train and lose less productive time than they would by taking a plane.
Also, if we really had bullet trains that could do 200+ MPH, you could have cross-country express trains that take less than 24 hours, so it wouldn't even have to be multiple days.
This is a point light in the middle of a regular polygon right? Why is this noteworthy? Is it that the light settles on all points evenly? Is it in spite of some sort of phase cancellation thing?