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* Posts by Bill Gray

98 posts • joined 12 Aug 2014

Page:

Chinese biz baron wants to shove his artificial moon where the sun doesn't shine – literally

Bill Gray

Re: Eight times brighter than the Moon?

"...Yes, but that's the dark side of the moon!"

Oddly enough, that's the _bright_ (as well as far) side of the moon, the one that's mostly mountains rather than mostly maria.

1
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Rookie almost wipes customer's entire inventory – unbeknownst to sysadmin

Bill Gray

Re: New contractor

Hadn't heard of that person being referred to as P45. I occasionally refer to him as the Orange Lord, or as He-Who-Must-Not-Be-Named-While-Eating.

4
2

First low-frequency fast radio burst to grace our skies detected at last

Bill Gray

Re: Uh, am I the only one

"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.

5
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US Declaration of Independence labeled hate speech by Facebook bots

Bill Gray

Re: George III

@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.

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Software changed the world, then died on the first of the month

Bill Gray

Re: Data format parsing

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 :

https://projectpluto.com/update8d.htm#time_entry

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.

6
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British egg producers saddened by Google salad emoji update

Bill Gray

Re: inclusion and diversity

"...Won't somebody think of the chickens, they've crossed many roads for us."

I dream of a world where chickens can cross the road without having their motives questioned.

7
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US Senator Ron Wyden to Pentagon: Encrypt your websites

Bill Gray

Re: Here's an Idea

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.

1
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Router admin? Bored? Let's play Battleships using BGP!

Bill Gray

Re: But but but...

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.

5
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Das blinkenlights are back thanks to RPi revival of the PDP-11

Bill Gray

Re: How noisy are the cooling fans?

"...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".

7
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Navy names new attack sub HMS Agincourt

Bill Gray

"Sure, all we need to do is lift 50,000 of pure water plus detectors into orbit and find some way to shield it against the trillions of neutrinos coming from the sun."

No problem. We'll do it at night.

16
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SpaceX finally Falcon flings NASA's TESS into orbit

Bill Gray

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.

9
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The first rule of maths class: Don't start a fight club

Bill Gray
Coat

Re: Trigonometry

Wait a sec... maybe I'm obtuse, but I've got a different angle on this, to some degree.

(Aren't you glad the above series of puns was finite?)

I did enter a pun contest once. I submitted ten puns, figuring that surely at least one would win. But no pun in ten did.

9
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Intel outside: Apple 'prepping' non-Chipzilla Macs by 2020 (stop us if you're having deja vu)

Bill Gray
Coat

Re: Spelling

That pun was the pits.

21
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Fleeing Facebook app users realise what they agreed to in apps years ago – total slurpage

Bill Gray

Re: Not an FB user. Can I delete my personal data?

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.

Oh, wait...

4
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Bill Gray

Re: I'm (not) sorry

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.

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Space, the final blunt-tier: Binary system ejected huge 'spliff' asteroid, boffins reckon

Bill Gray

Nope. A circular orbit has e=0. A parabolic one has e=1 (most comets are in something close to that). The earth's orbit has e=0.017, just a little non-circular. Anything with e>1 is hyperbolic. `Oumuamua has e=1.19. Infinite e would require infinite velocity.

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Horn star Sudan, last male northern white rhino, dies aged 45

Bill Gray

"...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.

3
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It's Pi day: Care to stuff a brand new Raspberry one in your wallet?

Bill Gray

Re: Dates

"...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).

https://projectpluto.com/temp/pi_rounds.pdf

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.

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Sneaky satellite launch raises risk of Gravity-style space collision

Bill Gray

Re: What About All The Other 194* Countries Who Might Want Their Own Satellites?

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.)

2
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Who can save us? It's 2018 and some email is still sent as cleartext

Bill Gray

@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.

2
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Bill Gray

Re: "e-mail I send says at the bottom: "My public key is"

"...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 bobdoe@example.com 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.)

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Bill Gray

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.

2
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NASA is pretty pleased with its pulsar-sniffing intergalactic GPS tech

Bill Gray

Re: Very impressive.

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.

0
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Engineer named Jason told to re-write the calendar

Bill Gray

Re: July and August must Go!

Dunno about the "proper" Latin names for an eleventh and twelfth month, but this may be of interest to calendar pedants :

http://www.tondering.dk/claus/cal/roman.php

(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.

3
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Interstellar space rock screams through Solar System

Bill Gray

Re: Another galaxy? Another star system?

@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).

2
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Bill Gray

Re: Interstellar space rock screams through Solar System

@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)

https://projectpluto.com/temp/2017u1.htm#speed .

3
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Capacitor maker zapped with price-fixing charge

Bill Gray

Re: What pisses me off about this @Doug

@PNGuinn :

https://en.wikipedia.org/wiki/Capacitor_plague

Improperly formulated electrolyte was causing gas to form, which built up in pressure until the caps blew their tops and spewed goo.

5
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'We think autonomous coding is a very real thing' – GitHub CEO imagines a future without programmers

Bill Gray

Re: the giants' shoulders

If I have not seen as far as others, it is because giants were standing on my shoulders.

(Not an original sentiment, but it does resonate with me some days.)

2
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Bill Gray

Re: Aircraft? Never get off the ground...

"They laughed at Galileo, and they laughed at Einstein. But they also laughed at Bozo the Clown."

Yes, sometimes a seemingly dumb idea (like aircraft) actually turns out to work. But I think this autonomous coding is more in the Bozo category.

2
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What is the probability of being drunk at work and also being tested? Let's find out! Correctly

Bill Gray

Socks in a drawer

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?

1
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Massive iPhone X leak trashes Apple's 10th anniversary circus

Bill Gray

Re: Apple has redrawn the poo emoji

"...So, these emoji things are not standardised in terms of appearance?"

Not at all. The Unicode consortium provides charts with example glyphs at

http://www.unicode.org/charts/

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."

0
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US focuses eyes in the sky as Hurricane Harvey starts to slam into Texas

Bill Gray

Re: "Harvey Dumps 9 TRILLION Tons of Water" at Washington Post

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:

https://www.washingtonpost.com/news/capital-weather-gang/wp/2017/08/27/texas-flood-disaster-harvey-has-unloaded-9-trillion-tons-of-water/

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.)

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.. ..-. / -.-- --- ..- / -.-. .- -. / .-. . .- -.. / - .... .. ... then a US Navy fondleslab just put you out of a job

Bill Gray

Re: meanwhile...

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.

9
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Russia launches non-terrifying satellite that focuses Sun's solar rays onto Earth

Bill Gray

Tracking info freely available

As with the ISS and a lot of other satellites, one can get data on when and where to look at

http://heavens-above.com/

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...

25
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Astroboffins spot tiniest star yet – we guess you could call it... small fry

Bill Gray

The radius is wrong.

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.

7
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Defend yourself against ISP tracking in an Trump-era free-for-all

Bill Gray
Pint

Re: What is metadata, exactly?

@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.

0
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Bill Gray

Re: Is this true?

"...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.)

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Bill Gray

Is this true?

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.")

0
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Ransomware scum have already unleashed kill-switch-free WannaCry‬pt‪ variant

Bill Gray

Re: Possibly not an intentional kill switch

@Norman Nescio : "...The single lookup of the unusual domain name was possibly a poor implementation of this [sandbox detection] technique."

I read the Malwaretech log (excellent description of why you'd look for a nonexistent domain to determine if you're sandboxed) and thought:

OK, so the virus writer should check a randomly generated domain, instead of a fixed one. That way, they can't all be registered, your virus can't be kill-switched the way this one was, and your virus can still tell if it's being run in a sandbox.

Except the folks creating sandboxes might take the precaution of checking the domain. Instead of returning a valid result for any garbage domain, check to see if it's been registered first. Suddenly, the virus can no longer tell that it's running in a sandbox.

Except then, the virus author checks four or five valid domains; if they all return identical results, you know you're running in a sandbox. (Reading further, I see that this method is actually used in some cases.)

Except that _then_, the sandbox authors do some revisions so that seemingly accurate results are returned that are actually remapped by the sandbox code.

This is all outside my area of expertise. Still, I could see a nearly endless cycle of fix/counter-fix going on here.

0
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User loses half of a CD-ROM in his boss's PC

Bill Gray

@Little Mouse : "A typical CD is only just able to hold itself together at those speeds IIRC."

Seemed unlikely to me. But Wikipedia says that as of 2004, the maximum speed of a CD was about 10400 RPM, or about 173 revolutions/second. For a 6-cm radius, that works out to a centrifugal acceleration (*) of about 7000 gees.

Now that I think about it... if it _wasn't_ close to the point of ripping things apart, it would make sense to try to get it to go faster.

(*) Yes, I know, there's "no such thing as centrifugal force." Sort of. You knew what I meant, though.

3
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Feel guilty for scoffing Easter chocolate? Good news: Scientists have made NEGATIVE mass

Bill Gray

@james 68 Sorry, just got 'round to noticing this!

I think the issue is that the earth's gravity would attract a "normal", positive mass, but would repel this exotic "negative" mass. (F=GMm/r^2; G=gravitational constant, M=earth's mass, and r=distance from the center of the earth are all positive, both for a "normal" mass and this "exotic" one; but the latter has opposite sign, causing the sign of F to flip.)

So the earth's gravity causes a repelling force on the negative-mass object... which causes it to be attracted. It is, effectively, a double negative cancelling out.

You're right that it's a serious question, in the added sense that the answer is (to both of us, and I'm pretty sure to physicists in general) unclear and may remain that way until an actual experiment is done.

Come to think of it... when I suggested that a positive mass would attract a negative mass, which would in turn repel the positive mass, so that they would accelerate across the universe, I figured it wouldn't help for spacecraft propulsion unless you got (say) moon-sized masses of each. But if you take a spacecraft and add a matching amount of negative mass, so that their net mass is zero, and you push it... does the acceleration (force/mass) tend toward infinity as the mass approaches zero? Inquiring minds _definitely_ want to find out!

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Bill Gray

I briefly thought it might float up. But such is not the case.

The gravitational force between the "negative mass" and the earth is proportional to the product of their masses. Normally, that force (GMm/r^2) would be a positive quantity. Here, it would be a negative quantity.

The _acceleration_ produced by that force would be what you get when you divide force by mass. For the negative mass, that divides out to be a positive quantity, and the atoms in the experiment fall to the floor at the usual 9.8 m/s^2.

The only odd thing here is that the earth is pushed away, admittedly very gently, by the negative mass. In theory, if you got a big mass m and a corresponding object with mass -m and put them next to each other, the one with mass m would be repelled by the negative mass and the one with mass -m would get attracted, and they'd go rushing off across the cosmos. I was about to say that I don't see where the energy would come from... but come to think of it, the one with positive mass gains energy mv^2/2, and the negative mass guy ends up with "negative energy" -mv^2/2. All of which seems very weird. But if one stipulates the concepts of negative mass and energy, it seems to be mathematically and physically consistent, albeit weird.

2
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RF pulses from dust collisions could be killing satellites

Bill Gray

Re: Slow

@nagyeger: "...'Most' orbital impacts are going to be 10-14km/s..."

Low-earth orbital speed is 8 km/s, relative to the earth's center. Most satellites, and therefore I assume most dust, is in lower/medium-inclination orbits, about 30 degrees for US launches, about 50 for launches from the former USSR, etc. All that stuff will indeed be moving, relative to each other, a bit slower. (Though if you're headed across the equator going south in a 30 degree inclination orbit, and hit a speck coming north from a similar orbit, 8 * (2 * sin(30)) = 8 km/s.)

Anyway. You raise an interesting point: satellites in higher (polar and near-polar) inclination orbits, such as some recon and communication satellites, ought to hit dust particles, on average, a little faster. Therefore, they ought to see these unexplained electrical failures more often.

On the other hand... since not as much stuff is in those orbits, they'll spend a good chunk of time going over the poles, in areas where the dust is less common. That'll work in the other direction, making them _less_ likely to fail.

However, when they _do_ fail, it should be more likely to happen at lower latitudes. If an analysis of failures showed that tendency, it would support this theory that dust impacts matter. I was going to suggest checking the frequency of failures in still higher orbits, but those are above the Van Allen belts, are in sunlight almost all the time instead of a bit over half the time, and therefore have other factors that wouldn't be easy to consider.

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Nuh-uh, Google, you WILL hand over emails stored on foreign servers, says US judge

Bill Gray

...The US cannot be trusted with data.

Errmmm... which government can be?

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Opportunity rover gets bored of spot it's explored since 2014

Bill Gray

Re: This article needs some translation to english

Were I writing that press release, I'd be keeping in mind that its goal is to ensure attention is paid to the Mars program and that funding continues. I'd phrase it in ways that the average voter or elected official would understand. I'd avoid use of metric units that might make me seem like some godless furriner, and stick with good ol' American units. To make the press release seem less elitist, I'd put in a reference to a sport for Real Men such as football.

You, as (I'm assuming) a non-American, just don't matter as far as the writer of that press release is concerned.

I've never seen a Russian or Chinese space agency press release, but it does seem to me that the ESA releases (which have their own issues) don't appear to be quite so narrowly Eurocentric. Once Brexit is accomplished and the UK is on its own for space affairs, I assume any press releases from the new British Space Agency will measure things in the height of Big Ben or something like that.

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PACK YOUR BAGS! Boffins spot Earth-size planet most likeliest yet to harbor alien life

Bill Gray

Re: mass vs density

@D@v3: we're 70% _surface_ water, but by volume... if you assumed we average six km of water on the surface, and have about a 6000 km radius, that'd make us about 1/3 % water by volume.

@LeeE: as I described, those numbers indicate something denser than _lead_, not just for the core, but for the entire planet. It'd need a core of something really unusual, like mercury or gold or osmium or uranium -- and a whopping big core, too, and still need some heavy stuff around it.

The radius was determined by seeing how much the star's brightness dropped when the planet went in front of it (which wasn't much; the planet is a _lot_ smaller than the star, so it blocked barely enough light to be noticeable.) The mass was determined by measuring the radial velocity of the star relative to us: when the planet is moving away from us, the star is moving (very slightly, because it's a lot heavier) toward us, and when the planet moves toward us... you get the idea; measure the difference in speed between "moving toward" and "moving away", combine with an estimate of the star's mass and the distance between the star and planet, and you can get a mass for the planet.

These are all fussy measurements we couldn't even have done a couple of decades ago, and we're still at the point where the errors are a good percentage of the quantities being measured. The most likely scenario is just that the radius was underestimated by, say, 10% (which would drop the density by 30%) and/or the mass was overestimated by a bit.

Standard practice in a scientific paper would have been to say something along the lines of "the radius is 1.4 +/- 0.2 times that of the earth, with a mass 7.0 +/- 2.1 times that of the earth." The sigmas probably got dropped in the press release.

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Bill Gray

Re: Even if we could get there, somehow

Seven times the mass, but 1.4 times larger. So a surface gravity 7/(1.4^2) = about 3.5 times ours. Still something where you'd want to put arch supports in your shoes.

But also a density 7/(1.4^3) = about 2.5 times ours, or a bit over 12.5 gm/cc. Iron comes in at 7.87, lead at 11.36. I haven't read the Fine Paper to see what error bars they give, but I'll take a guess that the planet is a little bigger and a little lighter than the given values, enough so to bring that density to a more reasonable value. Either that, or it has a core made of mercury (13.55) or gold (19.32) or uranium or something similarly exciting.

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Will the MOAB (Mother Of all AdBlockers) finally kill advertising?

Bill Gray

Re: A stupid question

True, and I'd not use it on a mobile (pay-per-byte) device. If you want to shovel a few megabytes of ads at me at home, and are okay with the fact that they'll all go to /dev/null, I'm OK with that.

It occurs to me that I don't know if this is a situation where I pay two cents to download El Reg ads, and El Reg profits by five cents. In which case, of course, if El Reg is willing to pay me three cents to do it, I'd be willing to scale it up so we can both profit.

I'm assuming I'm missing something. I'd expect somebody would have tried to implement something like this, just to provide a way to visit sites that insist you turn ad-blocking off (i.e., "oh, yeah, I'm taking all your ads... no need for you to know they're all getting binned.")

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Bill Gray
Megaphone

Re: TV Ads

At least in the US, there are indeed rules that would stop you from doubling the volume. There is (or at least, there was last I heard) a maximum permitted volume. However, there's nothing stopping you from running at that maximum volume all the time, resulting in a "shouty" effect (hence icon).

It does seem as if perhaps suitable logic could be added to use this to recognize and suppress at least that particular sort of advertisement...

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Bill Gray

A stupid question

("Stupid" = "don't really know much about how on-line advertising works")

OK, so I've got uBlock Origin installed. Without it, El Reg (for example) is a mess. But I'd be happy to support El Reg.

If, hypothetically, uBlock Origin (or similar blocker) were set to say: "on the following sites, download all the advertising but don't show it", do those sites profit?

Or would the blocker need to be modified to say: "on those sites, download the advertising and follow the links for a few ads picked at random, just to make sure El Reg profits and the ad tracking folks get some weird results"?

I'd assume one or both of the above would also suffice to get around sites that insist you turn off your ad blocker. I also realize that to work effectively, you'd have to trust scripts to the degree that a non-blocking browser would, i.e., more than I'd like to.

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