1473: "Location Sharing"

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1473: "Location Sharing"

Postby chris857 » Wed Jan 14, 2015 5:28 am UTC

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Alt: "Our phones must have great angular momentum sensors because the compasses really suck."

I get the uncertainty principle joke in the comic, but is the alt-text about the same thing (I'm tired, so maybe it isn't sinking in well).

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Re: 1473: "Location Sharing"

Postby Pfhorrest » Wed Jan 14, 2015 5:32 am UTC

Yes, it's pretty much the same thing. Your orientation (what a compass tells you) is the rotational equivalent to your position, and angular momentum is of course the rotational equivalent of your momentum, so the same problem applies. The more certain you are of how fast you're spinning, the less certain you are of where you're pointing, and vice versa.
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Re: 1473: "Location Sharing"

Postby rhomboidal » Wed Jan 14, 2015 5:44 am UTC

Hehe, I just turn on my phone's Heisenberg setting to take care of this for me.

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Re: 1473: "Location Sharing"

Postby dash » Wed Jan 14, 2015 6:14 am UTC

This is the best one I've seen in a long, long time.
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Re: 1473: "Location Sharing"

Postby PinkShinyRose » Wed Jan 14, 2015 6:54 am UTC

I thought that, while you cannot know both, it is possible to know neither. So couldn't phone manufacturers just be cheap with the compass?

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Re: 1473: "Location Sharing"

Postby azule » Wed Jan 14, 2015 7:46 am UTC

I don't know why you can't know both. How else does GPS work when you lose the signal for a few?
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Re: 1473: "Location Sharing"

Postby Eternal Density » Wed Jan 14, 2015 7:49 am UTC

Topical, my new leopad (Sorry I mean tablet) arrived yesterday so there was lots of location queries popping up.
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Re: 1473: "Location Sharing"

Postby lingomaniac88 » Wed Jan 14, 2015 8:16 am UTC

Well, you do have some degree of uncertainty due to floating-point arithmetic.
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Re: 1473: "Location Sharing"

Postby CharlieP » Wed Jan 14, 2015 8:57 am UTC

My main reaction to today's strip was to wonder how many people have only heard of the Heisenberg from Breaking Bad, and not his eponym.

Given the age of the target market, I bet lots of children first associated the names of Renaissance artists with mutated turtles, and I'm sure I had the same experience with other characters/performers in my youth but am struggling to think of examples first thing in the morning. Please chime in.
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Re: 1473: "Location Sharing"

Postby LockeZ » Wed Jan 14, 2015 9:46 am UTC

All I know about Heisenberg is that he made a blimp, but it blew up.

No, wait... he also sponsors a football trophy every year, right?

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Re: 1473: "Location Sharing"

Postby chalkie » Wed Jan 14, 2015 9:46 am UTC

azule wrote:I don't know why you can't know both. How else does GPS work when you lose the signal for a few?


The joke is a reference to Heisenberg's uncertainty principle :

Heisenberg - Quantum Mechanics, 1925-1927: The Uncertainty Principle. The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.

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Re: 1473: "Location Sharing"

Postby chalkie » Wed Jan 14, 2015 9:48 am UTC

Wait: Heisenberg was the cook, wasn't he?

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Re: 1473: "Location Sharing"

Postby Lazy Tommy » Wed Jan 14, 2015 10:08 am UTC

Pfhorrest wrote:Yes, it's pretty much the same thing. Your orientation (what a compass tells you) is the rotational equivalent to your position, and angular momentum is of course the rotational equivalent of your momentum, so the same problem applies. The more certain you are of how fast you're spinning, the less certain you are of where you're pointing, and vice versa.


What a smartphone compass tells you is based on measuring the ambient magnetic field. The perceived suckiness of smartphone compasses has a lot to do with how being inside a car distorts that field. (When magnetic compasses are installed in ships, there's an elaborate process of using small magnets to compensate for all the metal in the vicinity.)

GPSes in cars don't actually use the magnetic field. A TomTom or Garmin doesn't even have a compass, and smartphone navigation apps don't use the phone's compass, whether it's available or not; they use the first derivative of the GPS position to figure out in which direction you are moving, which is also why smartphone navigation apps don't get confused when you hold the phone in your hand and move it around while you're driving. (NOTE: don't hold the phone while you're driving, please! Pay attention to the road, and let a passenger fool around with the phone.)

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Re: 1473: "Location Sharing"

Postby azule » Wed Jan 14, 2015 10:12 am UTC

chalkie wrote:The joke is a reference to Heisenberg's uncertainty principle :

Heisenberg - Quantum Mechanics, 1925-1927: The Uncertainty Principle. The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.
IS that the joke? It's not stated anywhere. Maybe it's something similar. Doesn't the Principle only apply at the atomic level? Cell phones aren't atomic.
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Re: 1473: "Location Sharing"

Postby orthogon » Wed Jan 14, 2015 10:26 am UTC

Lazy Tommy wrote:What a smartphone compass tells you is based on measuring the ambient magnetic field. The perceived suckiness of smartphone compasses has a lot to do with how being inside a car distorts that field. (When magnetic compasses are installed in ships, there's an elaborate process of using small magnets to compensate for all the metal in the vicinity.)

I have big problems with phone compasses - when I hold the phone the compass swings wildly, but when I hand it to someone else, it works fine. My old HTC was particularly bad. Do I generate a magnetic field and my colleagues/friends don't? Is it to do with my blood group?

azule wrote:
chalkie wrote:The joke is a reference to Heisenberg's uncertainty principle :

Heisenberg - Quantum Mechanics, 1925-1927: The Uncertainty Principle. The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.
IS that the joke? It's not stated anywhere. Maybe it's something similar. Doesn't the Principle only apply at the atomic level? Cell phones aren't atomic.

Yes, that is the joke. The fact that it asks for momentum is the giveaway - if anything the app would ask for speed, but momentum is the quantity that participates in the Uncertainty Principle.

And, sure, the effect at the scale of a cellphone is imperceptible. It's a joke. See also At Home with the Heisenbergs.
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Re: 1473: "Location Sharing"

Postby CharlieP » Wed Jan 14, 2015 11:15 am UTC

Werner Heisenberg is pulled over by the police for speeding.

"Do you know how fast you were going, sir?"

"No, officer. But I know exactly where I am!"
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Re: 1473: "Location Sharing"

Postby LockeZ » Wed Jan 14, 2015 11:34 am UTC

azule wrote:Doesn't the Principle only apply at the atomic level? Cell phones aren't atomic.

Maybe yours isn't. Some of us like to stay on the cutting edge. My iPhone Nano may only have three quarters of a picosecond of battery life, but it's better than carrying around that giant brick you use.

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Re: 1473: "Location Sharing"

Postby azule » Wed Jan 14, 2015 12:30 pm UTC

:cry: I have big hands. :cry:
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Re: 1473: "Location Sharing"

Postby JohnMcL7 » Wed Jan 14, 2015 1:13 pm UTC

CharlieP wrote:My main reaction to today's strip was to wonder how many people have only heard of the Heisenberg from Breaking Bad, and not his eponym.

Given the age of the target market, I bet lots of children first associated the names of Renaissance artists with mutated turtles, and I'm sure I had the same experience with other characters/performers in my youth but am struggling to think of examples first thing in the morning. Please chime in.


Although I first learnt of Heisenberg in a physics class, when I think of the name it's the Heisenberg compensators in Star Trek that come to mind I guess because the idea amused me:

When asked by Time magazine in 1994, "How do the Heisenberg compensators work?" Michael Okuda replied, "They work just fine, thank you."

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Re: 1473: "Location Sharing"

Postby cellocgw » Wed Jan 14, 2015 1:14 pm UTC

rhomboidal wrote:Hehe, I just turn on my phone's Heisenberg setting to take care of this for me.


I believe you need the Heisenberg Compensator for maximum effect.
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Re: 1473: "Location Sharing"

Postby cellocgw » Wed Jan 14, 2015 1:15 pm UTC

LockeZ wrote:All I know about Heisenberg is that he made a blimp, but it blew up.

No, wait... he also sponsors a football trophy every year, right?


About all I could even attempt to add to that is -- The Thai-Tannic was sunk by a Heissenberg!
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Re: 1473: "Location Sharing"

Postby Lazy Tommy » Wed Jan 14, 2015 2:00 pm UTC

orthogon wrote:I have big problems with phone compasses - when I hold the phone the compass swings wildly, but when I hand it to someone else, it works fine. [...] Do I generate a magnetic field and my colleagues/friends don't? Is it to do with my blood group?

Yes, obviously. You should see a doctor right away. ;-)

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Re: 1473: "Location Sharing"

Postby orthogon » Wed Jan 14, 2015 2:06 pm UTC

Lazy Tommy wrote:
orthogon wrote:I have big problems with phone compasses - when I hold the phone the compass swings wildly, but when I hand it to someone else, it works fine. [...] Do I generate a magnetic field and my colleagues/friends don't? Is it to do with my blood group?

Yes, obviously. You should see a doctor right away. ;-)

Thanks, I will. I think I may have just discovered a new 21st Century, first world medical condition. Glaxo and friends will be rubbing their hands in anticipation. Do you think they'll name it after me? Or will it be called something like haemobiomagnetism syndrome? Should I avoid people with Electrosensitivity?
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1473: "Location Sharing"

Postby chalkie » Wed Jan 14, 2015 2:17 pm UTC

FTFY:
cellocgw wrote:
rhomboidal wrote:Hehe, I just turn on my phone's Heisenberg setting to take care of this for me.


I believe you need the Heisenberg Compensator for maximum effect.

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Re: 1473: "Location Sharing"

Postby algorerhythms » Wed Jan 14, 2015 2:33 pm UTC

rhomboidal wrote:Hehe, I just turn on my phone's Heisenberg setting to take care of this for me.

Careful about that. Last time I turned on that setting, my phone started cooking crystal meth and autodialed a Neo-Nazi gang.
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Re: 1473: "Location Sharing"

Postby chalkie » Wed Jan 14, 2015 2:36 pm UTC

azule wrote:IS that the joke? It's not stated anywhere. Maybe it's something similar. Doesn't the Principle only apply at the atomic level? Cell phones aren't atomic.


Actually I felt that in this comic the website represents scientists, the girl represents science itself, and the phone represents reality.
The scientists try to pin-down position & momentum, and at that point science forces reality to confound the scientists. </troll>

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Re: 1473: "Location Sharing"

Postby algorerhythms » Wed Jan 14, 2015 2:40 pm UTC

Thinking about it some more, though, she could click Allow on the momentum prompt, but it just means the website won't know her location anymore.
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Re: 1473: "Location Sharing"

Postby Klear » Wed Jan 14, 2015 2:53 pm UTC

I'll just leave this here...

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Re: 1473: "Location Sharing"

Postby Coyoty » Wed Jan 14, 2015 2:59 pm UTC

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Re: 1473: "Location Sharing"

Postby airdrik » Wed Jan 14, 2015 3:32 pm UTC

azule wrote:
chalkie wrote:The joke is a reference to Heisenberg's uncertainty principle :

Heisenberg - Quantum Mechanics, 1925-1927: The Uncertainty Principle. The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.
IS that the joke? It's not stated anywhere. Maybe it's something similar. Doesn't the Principle only apply at the atomic level? Cell phones aren't atomic.

I don't know about yours, by my cell phone is entirely composed of atoms, so it totally applies. It even uses sub-atomic particles in all of its calculations, so it most certainly cannot know both its position and momentum, otherwise it will promptly disconnect from any network services, format the hard drive clear its RAM/ROM and start sending out requests via bluetooth to find out its ID, what kind of a device it is and how to return to its factory settings.

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Re: 1473: "Location Sharing"

Postby PinkShinyRose » Wed Jan 14, 2015 4:44 pm UTC

You can have a vague idea of both, sufficient for most users of the phone. My phone navigation compass is horrible regardless of whether there's a huge chunk of metal nearby. It's only somewhat accurate inside a car, after driving for a bit (walking a while sometimes helps, but usually doesn't, I'm unsure about cycling as I generally only look at it intermittently on a bicycle.

EDIT: mounting a magnetic compass in an electronic device seems silly.

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Re: 1473: "Location Sharing"

Postby orthogon » Wed Jan 14, 2015 5:08 pm UTC

PinkShinyRose wrote:You can have a vague idea of both, sufficient for most users of the phone.


To put "vague" in perspective: by my calculations, if you know your position to 1mm accuracy, way better than current geolocation technologies, and you weigh* 60kg, you can know your velocity to within about 9x10-34m/s.

PinkShinyRose wrote:EDIT: mounting a magnetic compass in an electronic device seems silly.

I think it's quite hard to generate spurious magnetic fields strong enough to interfere with a compass, whereas vexatious electric fields are easy to generate by accident. I believe it has to do with the rate of drop-off of the near-field with distance: inverse-cube law for E-field and even faster for magnetic. I've never quite understood it, though.

*Let's not go there again.
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1473: "Location Sharing"

Postby Rachie » Wed Jan 14, 2015 5:09 pm UTC

I had a completely different interpretation of the comic. I saw the first panel as a nosy program trying to spy on the user's location, and getting denied. The program then tries to skirt around the answer by asking for momentum instead. Since momentum can be used to derive location as a form of inertial navigation, the program can trick the user into tracking by asking a seemingly benign question.

As for the highlighted buttons, I assumed this was either the program trying to intice the pressing of one button, a deliberately confusing toggle switch, or both. As a security paranoid person, not once did I ever consider someone would willingly allow this kind of tracking.

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Re: 1473: "Location Sharing"

Postby orthogon » Wed Jan 14, 2015 5:29 pm UTC

Rachie wrote:Since momentum can be used to derive location as a form of inertial navigation[...]

Only if it knows your initial location. (Actually, if it tracked you continuously for long enough, it could use the speed information to build up a picture of where there were roads, commercial and residential areas and even airports. By a process of elimination it might eventually be able to pin down your location).
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1473: "Location Sharing"

Postby gmalivuk » Wed Jan 14, 2015 5:32 pm UTC

Rachie wrote:I had a completely different interpretation of the comic. I saw the first panel as a nosy program trying to spy on the user's location, and getting denied. The program then tries to skirt around the answer by asking for momentum instead. Since momentum can be used to derive location as a form of inertial navigation, the program can trick the user into tracking by asking a seemingly benign question.

As for the highlighted buttons, I assumed this was either the program trying to intice the pressing of one button, a deliberately confusing toggle switch, or both. As a security paranoid person, not once did I ever consider someone would willingly allow this kind of tracking.
Considering how many programs do this kind of tracking without asking (apart from when you agreed to install it in the first place, when there's usually some kind of notification that it can check your location), you're probably already "willingly" allowing this kind of tracking whether you know it or not.

There are GPS spoofer apps, though, to feed false information to other apps that ask for it. Anyone tracking me likely thinks I spend a hell of a lot of time at the subway station nearest my house and very little time anywhere else.
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Re: 1473: "Location Sharing"

Postby Copper Bezel » Wed Jan 14, 2015 5:38 pm UTC

I have absolutely nothing to add to this discussion except to say that this is my single favorite non-What-If strip in months. "Laughing out loud" does not suitably convey my initial reaction.
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Re: 1473: "Location Sharing"

Postby Kit. » Wed Jan 14, 2015 5:49 pm UTC

PinkShinyRose wrote:My phone navigation compass is horrible regardless of whether there's a huge chunk of metal nearby. It's only somewhat accurate inside a car, after driving for a bit

Navigation compass should not use the magnetic compass inside the device, because it's not guaranteed that the device is oriented correctly.

Also, phone compass may need calibration to show anything meaningful at all. The easiest way to calibrate the compass is to open an app that uses the compass and to do this.

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Re: 1473: "Location Sharing"

Postby PinkShinyRose » Wed Jan 14, 2015 6:05 pm UTC

Kit. wrote:
PinkShinyRose wrote:My phone navigation compass is horrible regardless of whether there's a huge chunk of metal nearby. It's only somewhat accurate inside a car, after driving for a bit

Navigation compass should not use the magnetic compass inside the device, because it's not guaranteed that the device is oriented correctly.

Also, phone compass may need calibration to show anything meaningful at all. The easiest way to calibrate the compass is to open an app that uses the compass and to do this.

That makes sense when the phone is moving sufficiently to use a different data source, but it sucks when you're looking what direction you should walk in. Besides, if the phone is rotated, so is the screen...

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Re: 1473: "Location Sharing"

Postby Kit. » Wed Jan 14, 2015 6:19 pm UTC

Using the built-in compass in walking mode might be a good idea. But not in car mode with voice navigation.

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Re: 1473: "Location Sharing"

Postby PinkShinyRose » Wed Jan 14, 2015 6:41 pm UTC

Kit. wrote:Using the built-in compass in walking mode might be a good idea. But not in car mode with voice navigation.

I usually use on-board navigation when driving, so my phone navigation is for walking and cycling, usually without voice navigation (I find it easier to just stop and look at my phone once in a while when cycling). I also don't generally have voice enabled when driving, I just look at the screen for the next instruction, voice navigation tends to suck when you need to take turns in rapid succession (when you need the satnav most), so it's usually easier to just check at what road you need to end up.


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