Editing 1473: Location Sharing

{{comic
| number    = 1473
| date      = January 14, 2015
| title     = Location Sharing
| image     = location_sharing.png
| titletext = Our phones must have great angular momentum sensors because the compasses really suck.
}}

==Explanation==
{{incomplete|First draft.}}

In this comic, [[Megan]] is visiting a website on her mobile phone. After loading it, the website {{w|Location-based service|asks for her location}}, which Megan permits the phone to give. The choice between allowing or denying a website or app access to certain information is common among smartphones. The term "location sharing" specifically refers to when a smartphone user shares their location with such an entity. An example is a weather app which would need your location in order to find the correct forecast.

Megan is then asked her {{w|momentum}}, which she denies. The joke is based off of the Heisenberg {{w|uncertainty principle}}, which, in quantum mechanics, states that one cannot accurately know both the location and momentum of any particle simultaneously. However, since Megan is not a microscopic particle, it doesn't make any sense (it's simply funny) to say the the app is trying to violate Heisenberg's principle.

The ramifications of the uncertainty principle being violated in this context are unknown, but the comic might be alluding to security problems that appear if an untrusted application is given access to momentum data generated by the gyroscope. Access to gyroscope data can be used for reading passwords entered into the on-screen keyboard or even guessing keyboard strokes on a keyboard lying on the same table as the phone.

It could also be an attempt to get [[Megan]] to unwillingly reveal her weight (mass to be more exact), as the her mass can be inferred by dividing the momentum by her velocity (the velocity can be obtained by observing the change of her location information in time). In order to be feasible, however, the location must be polled at least twice, not once, as at least two location points are necessary to compute the velocity. Also, although commonly used interchangeably, the mass and the weight are not the same things. The mass is a measure of mechanical inertia of the body, while the weight is the force on the object due to gravity. As such, the weight of the same body is different on the surfaces of different celestial bodies (planets, etc). The weight can be computed from the mass by multiplying the latter by the {{w|Gravitational acceleration|gravitational acceleration}} of the given planet (obviously, Earth in this case). The tendency to keep the body weight in secret is a common stereotype about females, as it is believed that females tend to obsess about controlling (and not revealing) their weight in order to comply with the perceived expectations of the modern Western male society which tends to find slim females more attractive.

The title text refers to the inclusion of {{w|gyroscope}}s in modern cell phones that measure angular momentum, mostly to detect when the phone is tilted, but also used in a few mobile games. Randall suggests the poor accuracy of the compasses in mobile phones (measuring the angular position) is due to the gyroscopes being too good. (If both the gyroscope and the compasses were completely accurate, it would violate the uncertainty principle). Modern phones also include varied technologies (such as GPS) to pinpoint the user's location, with varying degrees of accuracy.

There is no way to measure absolute momentum directly in a mobile phone (well, anywhere else either). This is done normally by differentiating the position in time (from GPS signal) or by integrating the accelerometer signal. In the first case you obtain the average speed, the second technique is subject to numerical error adding up in time.

The uncertainty principle has previously been referenced in [[824: Guest Week: Bill Amend (FoxTrot)]]. It has also been discussed in relation to the two comics [[1404: Quantum Vacuum Virtual Plasma]] and [[1416: Pixels]].

==Transcript==
:[Megan is holding her phone. Above her is the text she can see on the screen:]
:This website wants to know your location.
:[Two buttons are below this text. The first is white with a black frame and black text. The second (the chosen button) also has a black frame, but inside the frame is a black rectangle with white text. Around the chosen button are small lines indication rays.]
:Deny
:'''Allow'''


:[Megan is holding her phone.]


:[Megan is holding her phone. Above her is again the text she can see on the screen. She makes a comment this time.]
:This website wants to know your momentum.
:[Two buttons are below this text. The first (the chosen button) has a black frame, but inside the frame is a black rectangle with white text. The second is white with a black frame and black text. Around the chosen button are small lines indication rays.]
:'''Deny'''
:Allow

:Megan: Nice try.

{{comic discussion}}
[[Category:Comics featuring Megan]]