Re: This story makes no sense...
"I'm not sure I like the way this thread is going"
Yeah, it's sew seamy. There's something about it I can't pin down.
OK, I'll zip it now... didn't mean to needle anybody.
110 posts • joined 12 Aug 2014
As a lad in the early 80s, we had a microwave with that exact way of notifying you when it was done. My teenage ears were much more sensitive than they are today, and I did a bit of disassembly and snipping to quiet the monster.
I now have a microwave with a similar feature, but my hearing has got to the point where the shrill BEEPs don't bother me as much. But I've no idea why a less piercing tone, somewhere around middle C, could not be used... surely, someone has done a careful study to determine the optimal alert tone frequency, and I have every confidence it is a few octaves below both the '80s microwave and my current microwave.
This point also has come up in discussion of US Sen. Elizabeth Warren's claims to have a Native American ancestor five generations back (i.e., 1/32 of her ancestry). She (foolishly, in my opinion) allowed Twatter taunts from the Orange Lord to persuade her to get and release a genetic test, which showed something more along the lines of it being 1/1024 of her ancestry. At the time, it was mentioned that even a properly "advanced" genetic test might miss a five-generations ancestor, for basically the reasons you suggest : you might get a good bit of DNA from that person, or nothing noticeable.
I wondered about this. It suggests Facebook would be (much) more profitable if it charged its users rather than selling their information.
Of course, what they would actually do is to charge users _and_ sell their information. (They have a fiduciary obligation to their shareholders, after all.)
I get the probability of having three identical numbers on six rolls as (5*4)*19^3/20^5 = 4.3%. Not all that surprising.
In any case, they did use the same die, so any weighting would have affected them identically.
Proper analysis of die bias would be interesting here... best method I can think of would be to float it to see which side comes up, but failing that, what occurs to me is to compute a unit vector for each of the twenty sides pointing out from the center to that face; then throw the die a bazillion times (long or short-scale bazillion, your choice) and add the vectors to see if they cancel. If it's biased, you should get a vector pointing toward the face that it's biased for.
Maybe I've just had cheap D20s and D12s, but I've not seen one that looks like a "casino" die (transparent so that inner weights are harder to hide, and any spots/numbers filled in with material of density similar to the rest of the die.) I'm sure somebody makes more verifiably unbiased D&D dice, though.
Serious answer : you can orbit just about anything.
The Earth has a density of about 5.5 gm/cm^3, and a low orbit around it takes about a hundred minutes. Same is true for _any_ object of that density. Bennu is about 12000 times smaller than Earth, but if it had the same density, you'd just orbit at about 1/12000 the speed (orbital speed would be about 60 cm/s) and still complete about one orbit every hundred minutes.
Your average asteroid has a somewhat lower density than that, though, more like 3 gm/cm^3. Orbital period runs as the inverse square root of density, so the orbital period would be only slightly longer than 100 minutes and speed only slightly less than 60 cm/s.
Also note that this is for an orbit really near the surface, which is easier for a roundish object such as the earth (disregarding equatorial bulge and atmosphere) than it would be for a small, irregular rock such as Bennu. If you need a speed of 60 cm/s near the surface (250 m from the object's center), then an orbit that is, say, a hundred times further out (25 km) would require a tenth that speed, or 6 cm/s. You'd have to do some very gentle maneuvering; exceed orbital speed by about 40% at any point, and you reach escape speed. But I suspect our friends at NASA are, in fact, being careful about that.
That image (which is of the _far_ side, incidentally; if it were the _dark_ side, it wouldn't be sunlit) is interesting. A small bit of measurement tells me the moon appears about six times larger than the earth (despite actually having a quarter the diameter). It must have been taken at a point about 16000 km from the moon, and about 400000 km from the earth.
I think it must have been taken by the Chinese Queqiao probe, sent up to the Earth-Moon L2 point earlier this year (to serve as a communications relay to the far side for an upcoming lander). I can't come up with anything else that would have had that viewpoint.
If you're an historian, 1 AD was preceded by the year 1 BC, and 1000 AD was 1999 years after 1000 BC.
If you're an astronomer (or, I submit, any sensible human being), the year +1 was preceded by the year 0, and the year 1000 was 2000 years after the year -1000. The solar eclipse that occurred (according to astronomers) on Oct 13 -982 also occurred (according to historians) on 13 Oct 983 BC. Both are accepted schemes within their disciplines, and fortunately, there's not much room for confusion. If you enter a year as -982 or 983 BC in the astronomy software I wrote, the code can figure out which year you "really" meant without ambiguity.
I can grudgingly accept the idea that the 20th century ran from 1901 Jan 1 to 2000 Dec 31, but only if you will accept the idea that the 1900s span from 1900 Jan 1 to 1999 Dec 31. Or that a date in 1980 would be both at the start of the '80s and at the end of the 198th decade.
The limit on resolution isn't in the sensor (those are about as good as they're going to get). It's in the optics. It's why astronomers want to make a hundred-meter telescope, and why spy satellites have mirrors a few meters across. Unless you rewrite the laws of physics, it's the only way to increase resolution.
I suppose the mini-satellites could do some signal interception. They're quite small; I'd expect it to be a challenge to add anything unrelated to their stated purpose... but I could imagine it being done, or a few special-purpose sats slipped in among the 12000. That would just be a technical challenge; getting detailed images of people from orbit with ten-cm optics is blocked by fundamental physics.
Looking at the catalogue of orbital elements for "tracked" objects,
it has 17547 objects in it today, most of them junk (first object listed is Vanguard 1, from 1958). The lowest objects are as small as ten centimeters; as you go up, the size limit increases (it's hard to track something that small in a higher orbit). Add higher-orbiting objects that aren't catalogued, and you could reach 50K without much trouble.
My guess would be that the 500000 object count has to involve some extrapolation and sampling; it's not an actual enumeration. It's not as easy to verify as the 17547 count, but it seems in line with what we know about the larger objects that are individually tracked.
In re "acquiring escape velocity" : if you have a way in which two objects at orbital speed can collide and somehow accelerate one of them to escape speed, call your patent attorney. (Actually, don't bother; I believe that inventions that claim to generate energy from nowhere are usually non-patentable, and that's what you'd have here.) The usual result of orbital collisions is just lots of shrapnel and a lot of kinetic energy being converted to heat.
The 17000-odd objects get observed frequently, from many countries. Your suspicion of my nation's government is obviously sensible. But even a stopped clock is right twice a day.
"But we're detecting it at light years, which would imply a signal strong enough to be used at interstellar distance."
We're detecting _echoes_ from Mercury at interplanetary distances. Big difference. Radar detection drops as the _fourth power_ of distance; move an object ten times further away, and it collects 1/100 as many radar photons, and then you lose another factor of 100 on the way back. (Which is why almost all radar distance/range rate measurements are done on near-earth objects, only a few times further away than the moon; it takes a _big_ object for such measurements to work over longer distances, and _huge_ amounts of power.)
This is also why the folks tracking artificial satellites use radar for low-earth objects and optical observations for objects in higher orbits. At least for publicly released data, the US military satellite surveillance folks can track objects only a few centimeters across in low-earth orbit, about 350 km away. But an object orbiting as far away as the moon would have to be a few tens of kilometers across to return a similar signal.
If you were on a background star when the big interplanetary radars pinged (for example) Mercury, I _think_ you would get a series of pulses. You'd only see it once, though; the next time we pinged Mercury, it would have moved and some other aliens would get the signal.
@Kane : you laugh, but...
Some years back, there was a play titled "The Madness of George III". When a movie was made based on it, the title was changed to "The Madness of King George". It was felt that had the III been kept, some American moviegoers might think they'd missed episodes I and II.
I write software for astronomers. The range of formats we have to deal with is astonishing, including negative years, times given in decimal days or hours or minutes or in Julian Day or Modified Julian Day or years/days since beginning of the year. I eventually decided that rather than train the users, I needed a library function that could parse just about anything humans threw at it :
I have the advantage here that astronomers (usually) stick to year/month/day order. I have the disadvantage that astronomers may be interested in what the sky looked like in, say, 9 AD, so a date such as 9/7/5 could be the fifth of July in 9 AD, or the seventh of September in 5 AD... which is why I urge people to use three-letter month abbreviations and four-digit years : 0009 Sep 5. Put that in any order, and it'll make sense.
I am in the position of both writing the software and having to document it and support users. So an extra few hours of effort adapting code to users pays off in less time spent explaining what I did. In my first job, I only wrote code and it was some other schmuck's job to support it; I must confess that this made me much more casual about usability. Dealing with angry customers wasn't my department.
You jest, but I do wonder if you may be on to something here.
I would submit to the Court that encryption has been subject to weapons export restrictions under US law in the past. In effect, it is already the stance of the US Government that encryption is a weapon. Further, the language of the Second Amendment (the bit about "a well-regulated Militia") makes it clear that the intent of its authors was to ensure the ability of citizens and individual States to resist tyranny. Communicating without governmental eavesdropping is clearly important to that ability.
From the linked article :
"...the final blow to my friend AS203729 was dealt on the 68th move. Making me the first winner of a board game conducted done over a public internet routing protocol."
As I recall, Battleship is usually played with each player launching a "salvo" of five shots, and being told in reply something along the lines of: "You got two hits on destroyers, one on my battleship, two misses." It sounds as if this game is being played with single shots, which should simplify the whole process.
I read an interesting article a while back about an effort to determine an optimal strategy for Battleship. It's a tough game to analyze, with a huge decision tree.
"...batteries die, power grids go down, but slide rules need neither."
I keep meaning to put my slide rule and tables of logarithmic and trigonometric functions into a little glassed-in case, with a small hammer and sign reading "break glass in case of power failure".
On the off chance that you're serious here:
Our littering habits are a serious problem in low-earth orbit, and somewhat so in the geosynch belt. Something really ought to be done about this (not having ASAT tests make more shrapnel would be a nice start). Danger at other altitudes is minimal, because Space Is Big.
The second stage will be in an heliocentric orbit, just inside that of the earth (but touching it at aphelion). Its orbital period should be roughly 8/9 of a year, meaning there's a chance we'll see it in eight years and mistake it for a near-earth asteroid (that sort of thing has happened several times already, once with the SIV-B stage from Apollo 12, which came back to earth's neighborhood for a bit in 2003.)
But compared to the amount of rocks already in heliocentric orbit, we're in no danger of having things get cluttered up there.
I'm in a similar position. I'v never been on Facebook, but people have given FB my e-mail address so that I could receive an invitation to "be their friend". Examining their data, I'm sure FB has noted that many live in a particular part of the world, they lean in a particular direction politically, a bunch are interested in a particular area of science, and that they cluster around a particular age. You could make some reasonably solid guesses about where I live, my political leanings and scientific interests, etc. just from that data, none of which was willingly provided by me.
I'd be quite interested to know what data Facebook accumulates on non-users and, specifically, what non-users can do to restrict use of that data. It would be great if journalists from a tech news site investigated those questions and shared what they learned with us.
I've never had a Facebook account. But people have given Facebook my e-mail address so that FB can send me an invitation to "be their friend". I've long assumed that FB therefore knows a long list of people who wanted me to "be their friend" and has done their best to profile me based on my supposed associates.
Lacking a FB account, though, I have no way to control what FB knows about me, or even to _know_ what FB knows about me. In some ways, having an account would actually give me more control over the situation than I currently have. Which, I need hardly add, is bonkers.
"...All that for a substance which you can get from biting your nails."
Hmmm... I wonder if synthetic rhino horn could be made from human fingernails, at a price low enough to compete with poachers? I suspect there would be no end of people willing to contribute their trimmings.
Some lying to the horn dealers might be required ("oh, yes, this came from a for-real, genuine rhino!"), but I'd say it would be in a good cause.
"...So is 22nd of July 'Pi Approximation Day' in DD/MM countries then?"
I will be making a pie (Key Lime) for my family to celebrate today. I don't expect to get them to join me in singing a few rounds (which are, of course, the traditional music for Pi Day, similar to carols for Christmas).
My wife and daughter do not, in general, really get into the holiday spirit; Pi Day is more part of their nerdly husband/father's cultural heritage. But they'll eat the pie.
But a couple of years ago, my wife made some quite tasty quiches for 22/7. A quiche is, of course, "approximately" a pie.
Possibly (another) good argument for improving space surveillance capabilities. It would be good in any case to track the smaller stuff; if your payload is hit by an object a few centimeters across, it can ruin your day quite as thoroughly as one ten centimeters across. Quite aside from non-US companies, being able to launch and track smaller satellites would help everybody.
Allowing/encouraging smaller payloads would actually improve the space debris problem, in that smaller objects decay faster. (Of course, smaller payloads would also mean you could launch more of them, so the net benefit/drawback might go either way.)
@AC recommending Autocrypt : thank you. Looks as if they're doing exactly what I describe, except (a) keys are offered through headers rather than in the message body, which makes sense and (b) they've thought through the bits I'd cavalierly waved aside (how to handle group e-mails, for example, and what to do if somebody loses their key or has multiple devices.)
However, they explicitly state (as I did) that this is "opportunistic" encryption, without all messages encrypted at all times and without a way to authenticate you're who you say you are. It'll make life more difficult for spooks, but not impossible. The idea is not to let the perfect be the enemy of the good. Seems a worthy goal.
"...The issue is you need a key your recipients will trust - encryption without authentication is of little use."
You have a lot of company in that sentiment. The scheme I describe is -- as I said -- imperfect. All it means is that if I e-mail firstname.lastname@example.org and get an encrypted reply, further traffic can be read by me and whoever replied.
Yes, yes, I know... the NSA, GCHQ, etc. may have intercepted the original e-mail and replied, spoofing Bob's e-mail address. I'll think I'm talking to Bob, but I'm really not. But most of us aren't up against the NSA. (Though you and I may be, after they read these comments.)
The fact that my front door won't resist a battering ram doesn't mean I don't lock it (current e-mail is more analogous to leaving the door open with a "Welcome Thieves" sign). If I'm an NSA target, I'll make sure "Bob" is really "Bob" through some other means, such as talking with him to ask if he got any of my mails. (Actually, if I'm _that_ important a target, I'll have to assume any electronic devices have been hacked from the get-go and will have to resort to paper-and-pencil one-time pads... no matter how paranoid you get, it's hard to keep up.)
I've wondered about this.
At the very least, I'd like to have an option wherein each (unencrypted) e-mail I send says at the bottom: "My public key is..." Suitable e-mail clients recognizing that line would ensure that replies were sent encrypted with that key, and included the public key of the person I'd e-mailed.
At that point, encryption is established at both ends and subsequent messages are end-to-end encrypted.
Yes, I realize this is highly imperfect. The first message I send isn't encrypted. Nobody is authenticated; I don't know if my correspondent is a dog. (Various things could be "bolted on" to implement perfect forward secrecy and to tell people your private key has been compromised; I've left that out for simplicity.) However, Grandma wouldn't have to know she's using this scheme, and it's immensely better than the current idiocy of doing absolutely nothing.
A benefit of such a scheme is that it would result in a lot of end-to-end encrypted communication. At present, use of such is probably rare enough to be a useful flag to three-letter agencies: they may not know what you're saying, but it's probably something "subversive". If E2E was everywhere, they might have to engage in actual police work.
Measuring star positions to determine your position in space won't do it. Certainly not yet.
The GAIA astrometric satellite will, we expect, get parallaxes and positions to (roughly) the 20 microarcsecond level. That involves multiple measurements over a multi-year mission, but let's say a future instrument could get to that level of precision. Let's also say that you have some stars within, say, four light-years; those are the reference points from which you're measuring your position. In that case, your positional accuracy is the distance subtended at a distance of four light years by a 20 microarcsec angle, which is... um... I'm getting about 4000 km. Better than I would have expected, actually. But the pulsars would still be the way to go.
Sadly, interstellar travel is still a ways off. But I _could_ imagine optical methods working within the solar system: image three asteroids with known positions (quite well known already, and about to become better due to GAIA), measure their position relative to background stars, and you could have positioning competitive to pulsar timing methods.
Dunno about the "proper" Latin names for an eleventh and twelfth month, but this may be of interest to calendar pedants :
(As part of Julius Caesar's calendar reform, two months were inserted between November and December in 46 BC. "It has been suggested that their names were Undecember and Duodecember, but that is doubtful, as this would mean that the names of the last four months were derived from the Latin words for nine, eleven, twelve, ten – in that order." Note that this was a one-off event; the Roman calendar required occasional leap months, but that hadn't been done for a while. The extra two months were to get things back on track.)
So... JFMAMJJASONUDD. But if we wanted logic, we'd have switched to the French Republican calendar.
@aqk - no. See https://www.projectpluto.com/temp/2017u1.htm#alt_ideas . Yours is debunked idea #2. (If it's any consolation, some professional astronomers had the same thought at first.)
BTW, definitely this galaxy, at 26 km/s incoming speed. From anyplace else, we'd be talking hundreds of km/s (and probably wouldn't have noticed it).
@Destroy All Monsters :
"...I would have expect a bit more [speed] somehow."
That's 26 km/s at infinity. Look at it from the sun (really, the solar system barycenter) a few centuries back, and it would be barrelling toward you at 26.07 +/- 0.10 km/s. A few centuries from now, it'll be going away at the same speed. As it went by the Sun, it went much faster. Further details at (warning, I'm author of the linked page)
I've long tended to grab two socks from the drawer in the morning without really checking to see if they match. SWMBO objected to this behavior. I caved in (always a good idea on minor issues; choose one's battles carefully, etc.) and have since taken a moment or two to ensure a match. But I did explain to her that my previous behavior was just in memory of (seemingly countless) probability problems as a lad such as:
Eddie has five red socks, three black socks, and two white socks. If Eddie grabs two socks in the morning at random, what's the probability that he'll grab two socks that match?
"...So, these emoji things are not standardised in terms of appearance?"
Not at all. The Unicode consortium provides charts with example glyphs at
Each chart contains boilerplate that says, among other things :
"The shapes of the reference glyphs used in these code charts are not prescriptive. Considerable variation is to be expected in actual fonts."
You threw me there for a bit. I immediately converted that mentally to being enough water to cover nine million km^2 to a depth of one meter or metre (a (metric) ton(ne) of water is one cubic meter, so a square kilometer a meter deep would be 1e+6 cubic meters or tonnes of water.) The United States have roughly that area. This is a big storm, but I don't think it could cover the US to a depth of one meter. I think this is the article you had in mind:
Fortunately, it's more like 9e+12 _gallons_, or 34e+12 liters or however you want to spell it, or 34e+9 cubic meters of water. You were only wrong by a factor of 300... not quite wrong enough to qualify you for high elective office, but close.
(The URL says 'tons'; the article says 'gallons'. Note that while the corrected figure wouldn't cover the US in a meter of water, it _would_ cover Wales in about 1.5 metres of water... that being the unit of area more appropriate to this site anyway.)
Had some visiting youngsters tell me a few days back that in schools where cellphones are banned, kids set them to ring at a high frequency, such that they can hear them but annoying older people can't. I could imagine kids communicating with Morse code pitched high enough to get past teachers.
As with the ISS and a lot of other satellites, one can get data on when and where to look at
You do have to be reasonably careful to give the site a decent idea as to where you are on our green planet, of course.
As they note, the actual brightness is unknown at this point (I don't know, for example, if the object has even emerged from its cube; if it hasn't, it would probably be in faint-star realm.) Unlike, for example, the Iridium satellites, the orientation is essentially "tumbling randomly", so you might get bright flashes if one of the facets flashes toward you and not if it doesn't.
Especially as it's a student project, there's some risk that it won't deploy at all and will remain a cube rather than a tetrahedron. Still a Platonic solid, though.
If you _do_ spot it, please post a report here so the rest of us have some clue what to expect...
Or maybe the mass. But if you tell me the object has about a twelfth the mass of the Sun, and a twelfth of its radius, then you're also telling me it has a density 144 times that of the Sun, or about 200 times that of water.
An object the size of Saturn (which _would_ be about a twelfth of a solar diameter) isn't big enough to cause fusion to happen; you've got to be a fair bit bigger than Jupiter to do that. I think a twelfth of a solar mass is in the right ballpark, enough bigger than a brown dwarf to produce at least some light, but perhaps at low enough density to not show up when transiting a larger, more energetic star.
@User McUser :
"...But that's pretty much all they get with HTTPS; the rest of the connection info, including the requested URI, is encrypted"
Thank you; that's what I was looking for in my query above.
It sounds as if using my ISP directly to access Wikipedia, Google, etc. tells my ISP I'm pretty much like any other Internet user. If I want to access a site associated with sedition, blasphemy, pornography, and acts contrary to the laws of Dog and man, I should go through Tor or a VPN and accept the slowdown implicit in that.
"...If they know the domain, and the exact time of the connection, they can shifty off and demand further info"
True enough. I'm thinking in terms of protection from marketing of data by my ISP and other large corporations. If my government really takes that level of interest in me, I'm not sure there really is a defense. (Though I agree, it should be made as difficult as possible for them. Personally, I lead a boring life and can't think of anything I've done on-line that needs to be private. But it's my duty, as a patriotic American, to help my country (and yours) not slide further into totalitarianism.)
OK, go easy on me; this is well outside my realm of expertise :
"...[Even with HTTPS, your ISP] can still learn a heck of a lot about your request such as the base domain. It can see that you've requested, for example, wikipedia.org, even if it can't see which page <strikeout>your</strikeout> you're connected to"
I interpret this to mean that, when I ask for https://www.xyz.com/randompage.html?etc,
the ISP will know I've requested something from xyz.com, but won't know it was randompage.html?etc.
If my ISP knows that I access Wikipedia, DuckDuckGo, etc., _but not what exactly I was after_, I don't mind all that much. I suppose what I'd then wish to have is the ability to tell my browser that certain sites go through my ISP, and everything else through a VPN.
I'd even be willing to fork over money to my ISP if they would, internally, VPN any of the traffic I _did_ send through them. That is to say, Google, etc. would know that a page had been requested, but not that the request had come from me. Seems to me the ISPs might wish to do that anyway, since they are now (in theory) competitors with Google for learning everything about you. (Though I suppose they may set up deals: "we'll tell you who asked for that page if you'll tell us which page they asked for.")
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