Science, SciFi, Technology

Kessler-resistant real-life force-fields?

Idle thought at this stage.

The Kessler syndrome (also called the Kessler effect, collisional cascading or ablation cascade), proposed by the NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in low earth orbit (LEO) is high enough that collisions between objects could cause a cascade where each collision generates space debris that increases the likelihood of further collisions.

Kessler syndrome, Wikipedia

If all objects in Earth orbit were required to have an electrical charge (all negative, let’s say), how strong would that charge have to be to prevent collisions?

Also, how long would they remain charged, given the ionosphere, solar wind, Van Allen belts, etc?

Also, how do you apply charge to space junk already present? Rely on it picking up charge when it collides with new objects? Or is it possible to use an electron gun to charge them from a distance? And if so, what’s the trade-off between beam voltage, distance, and maximum charge (presumably shape dependent)?

And if you can apply charge remotely, is this even the best way to deal with them, rather than collecting them all in a large net and de-orbiting them?

Science, Technology

You won’t believe how fast transistors are

A transistor in a CPU is smaller and faster than a synapse in one of your brain’s neurons by about the same ratio that a wolf is smaller and faster than a hill.




CPU: 11nm transistors, 30GHz transition rate (transistors flip significantly faster than overall clock speed)

Neurons: 1µm synapses, 200Hz pulse rate

Wolves: 1.6m long, average range 25 km/day

Hills: 145m tall (widely variable, of course), continental drift 2 cm/year

1µm/11nm ≅ 1.6m/145m
200Hz/30GHz ≅ (Continental drift 2 cm/year) / (Average range 25 km/day)

Futurology, Software, Technology

Hyperinflation in the attention economy: what succeeds adverts?


Lots of people block them because they’re really really annoying. (Also a major security risk that slows down your browsing experience, but I doubt that’s the main reason.)

Because adverts are executable (who thought that was a good idea?), they also get used for cryptocurrency mining. Really inefficient cryptocurrency mining, but still.

Because they cost money, there is a financial incentive to systematically defraud advertisers by showing lots of real, paid-for, adverts to lots of fake users. (See also: adverts are executable. Can one advert download ten more? Even sneakily in the background will do, the user doesn’t need to see them.)

Because of the faked consumption (amongst other reasons), advertisers don’t get good value for money, lowering demand; because of lowered demand, websites get less money than they would under an efficient system; because of something which seems analogous to hyperinflation (but affecting the supply of spaces in which to advertise rather than the supply of money), websites are crowded with adverts; because of the excess of adverts, lots of people block them.

What if there was a better way?

Cut out the middle man, explicitly fund your website with your own cryptocurrency mining? Users see no adverts, don’t have their attention syphoned away.

Challenge: the problem I’m calling hyperinflation of attention (probably inaccurately, but it’s a good metaphor) would still apply with cryptocurrency mining resource supply. This is already a separate problem with cryptocurrency mining — way too many people are spending way too many resources on something which is only counting and storing value but without fundamentally adding value to the system.

Potential solution: a better cryptocurrency, one which actually does something useful. Useful work such as SETI@home or folding@home — if it must be a currency, then perhaps one where each unit of useful work gets exchanged for a token which can be traded or redeemed with the organisation which produced it, in much the same way that banknotes could, for a long time, be taken to a central bank and exchanged for gold. And the token could be redeemed for whatever is economically useful — a user may perform 1e9 operations now in exchange for a token which would given them 2e9 floating point operations in five years (by which time floating point operations should be 10 times cheaper); or the user decodes two human genomes now in exchange for a token to decode one of their choice later; or whatever.

A separate, but solvable, issue is that the only things I can think of which are processing-power-limited right now are research (climate forecasts, particle physics, brain simulation, simulated drug testing, AI), or used directly by the consumer (video game graphics), or are a colossal waste of resources (bitcoin, spam) — I’ll freely admit this list may be just down to ignorance on my part — so far as I can see, the only one of those which pairs website visitors with actual income would be the video games… but even then it would be utter insanity for the paid customers to have their image rendering offloaded onto the non-payers. The clear solution to this is the same sort of mechanism that currently “solves” advertising: automated auction by those who want to buy your CPU time and websites that want to sell access to your CPU time.

Downside: this will kill you batteries if you don’t disable JavaScript.

Futurology, Technology

Musk City, Antarctica

One of the criticisms of a Mars colony is that Antarctica is more hospitable in literally every regard (you might argue that the 6-month day and the 6-month night makes it less hospitable, to which I would reply that light bulbs exist and you’d need light bulbs all year round on Mars to avoid SAD-like symptoms).

I’ve just realised the 2017 BFR will be able to get you anywhere in Antarctica, from any launch site on Earth, in no more than 45 minutes, at the cost of long-distance economy passenger flights, and that the Mars plan involves making fuel and oxidiser out of atmospheric CO₂ and frozen water ice so no infrastructure needs to be shipped conventionally before the first landing.

Science, Technology

Railgun notes #2

[Following previous railgun notes, which has been updated with corrections]

F = B·I·l
B = 1 tesla

I: Current = Voltage / Resistance
l: Length of armature in meters

F = 1 tesla · V/R · l
F = m · a
∴ a = (1 tesla · V/R · l) / m

Using liquid mercury, let cavity be 1cm square, consider section 1cm long:
∴ l = 0.01 m
Resistivity: 961 nΩ·m
∴ Resistance R = ((961 nΩ·m)*0.01m)/(0.01m^2) = 9.6×10^-7 Ω
Volume: 1 millilitre
∴ Mass m = ~13.56 gram = 1.356e-2 kg
∴ a = (1 tesla · V/(9.6×10^-7 Ω) · (0.01 m)) / (1.356e-2 kg)

Let target velocity = Escape velocity = 11200 m/s = 1.12e4 m/s:
Railgun length s = 1/2 · a · t^2
And v = a · t
∴ t = v / a
∴ s = 1/2 · a · (v / a)^2
∴ s = 1/2 · a · v^2 / a^2
∴ s = 1/2 · v^2 / a
∴ s = 1/2 · ((1.12e4 m/s)^2) / ((1 tesla · V/(9.6×10^-7 Ω) · (0.01 m)) / (1.356e-2 kg))

@250V: s = 0.3266 m (matches previous result)

@1V: s = 81.65 m
I = V/R = 1V / 9.6×10^-7 Ω = 1.042e6 A
P = I · V = 1V · 1.042e6 A = 1.042e6 W

Duration between rails:
t = v / a
∴ t = (1.12e4 m/s) / a
∴ t = (1.12e4 m/s) / ( (1 tesla · V/(9.6×10^-7 Ω) · (0.01 m)) / (1.356e-2 kg) )

(Different formula than before, but produces same values)
@1V: t = 0.01458 seconds

Electrical energy usage: E = P · t
@1V: E = 1.042e6 W · 0.01458 seconds = 1.519e4 joules

Kinetic energy: E = 1/2 · m · v^2 = 8.505e5 joules

Kinetic energy out shouldn’t exceed electrical energy used, so something has gone wrong.

AI, Software, Technology

Automated detection of propaganda and cultural bias

The ability of word2vec to detect relationships between words (for example that “man” is to “king” as “woman” is to “queen”) can already be used to detect biases. Indeed, the biases are so easy to find, so blatant, that they are embarrassing.

Can this automated detection of cultural bias be used to detect deliberate bias, such as propaganda? It depends in part on how large the sample set is, and in part on how little data the model needs to become effective.

I suspect that such a tool would work only for long-form propaganda, and for detecting people who start to believe and repeat that propaganda: individual tweets — or even newspaper articles — are likely to be far too short for these tools, but the combined output of all their tweets (or a year of some journalist’s articles) might be sufficient.

If it is at all possible, it would of course be very useful. For a few hours, until the propagandists started using the same tool the way we now all use spell checkers — they’re professionals, after all, who will use the best tools money can buy.

That’s the problem with A.I., as well as the promise: it’s a tool for thinking faster, and it’s a tool which is very evenly distributed throughout society, not just in the hands of those we approve of.

Of course… are we right about who we approve of, or is our hatred of Them just because of propaganda we’ve fallen for ourselves?

(Note: I’ve seen people, call them Bobs, saying “x is propaganda”, but I’ve never been able to convince any of the Bobs that they are just as likely to fall for propaganda as the people they are convinced have fallen for propaganda. If you have any suggestions, please comment).


iOS or Android?

“What’s best” always depends on what you want to do. This is my impression of which of iOS and Android is better in different circumstances:

Lowest cost Android
Any specific single feature (best camera, dual-sim, FM radio, etc.) Android
Best build quality iOS
Easy to modify Android
Secure from other people modifying it without you knowing iOS
Smart Watch iOS
Smart Watch if you don’t like the Apple Watch Android
Virtual Reality Android
Voice control interface Android
MacOS integration iOS
Meaningful choice of web browsers Android