Search found 910 matches

by mfb
Thu Mar 30, 2017 10:18 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9656
Views: 1402490

Re: Coding: Fleeting Thoughts

:hy: If the two instances of x are different values, then changing the order of the operations doesn't necessarily help. You can still get large rounding errors, or even NaN/other stuff if they are too close to zero. A different number format? Finding the mathematical cause of the cancellation and u...
by mfb
Thu Mar 30, 2017 8:00 pm UTC
Forum: Science
Topic: Is terraforming Uranus and Neptune possible?
Replies: 19
Views: 1141

Re: Is terraforming Uranus and Neptune possible?

Removing the gas might need the Sun's output of a year, but fusing the hydrogen in it produces orders of magnitude more, and the core could be interesting for resources if the inner planets are not sufficient any more. Who knows that an advanced type-2 civilization wants? Cold and dark is probably n...
by mfb
Thu Mar 30, 2017 7:46 pm UTC
Forum: Mathematics
Topic: Futurama Puzzle Game
Replies: 5
Views: 941

Re: Futurama Puzzle Game

That is an interesting question. Of course, in the episode the problem was fixed by adding two people who hadn't swapped yet, which adds enough available swaps to always make it solvable. That could be an approach. Make some random arrangement using only N-2 people, then find a solution using all N...
by mfb
Thu Mar 30, 2017 7:33 pm UTC
Forum: Science
Topic: Storing Nuclear Waste on the Moon
Replies: 57
Views: 3544

Re: Storing Nuclear Waste on the Moon

Even if we completely ignore the historical decays and suddenly stop all coal power plants, we'll get the radioactivity of all nuclear accidents together from coal in 40 years. I completely agree on the health-and-safety merits of nuclear power relative to coal, but this statistic feels slightly di...
by mfb
Wed Mar 29, 2017 11:59 pm UTC
Forum: Science
Topic: Storing Nuclear Waste on the Moon
Replies: 57
Views: 3544

Re: Storing Nuclear Waste on the Moon

Lets also remember for a second that a significant amount of nuclear waste is produced by coal-fired power stations, and Im not sure about modern power stations or "clean coal" but most of it is ejected into the atmosphere apparently. A 1,000 MW coal-burning power plant could have an unco...
by mfb
Wed Mar 29, 2017 10:30 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1002: "Game AIs"
Replies: 240
Views: 60138

Re: 1002: "Game AIs"

I was asking about SC, and the SC AI duodecimus mentioned in particular. I know that computing power in general can be an issue, but it does not have to.
by mfb
Mon Mar 27, 2017 3:21 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1002: "Game AIs"
Replies: 240
Views: 60138

Re: 1002: "Game AIs"

Is computing power an issue?
How much does the AI learn in terms of strategy, and how much is it manual strategy input from humans?
by mfb
Sat Mar 25, 2017 10:05 pm UTC
Forum: Science
Topic: Storing Nuclear Waste on the Moon
Replies: 57
Views: 3544

Re: Storing Nuclear Waste on the Moon

This series of documentaries on the dangers of storing the waste on the moon is an eye-opener: https://en.wikipedia.org/wiki/Space:_1999 "Documentaries" nuclear waste stored on the Moon's far side explodes, knocking the Moon out of orbit and sending it, as well as the 311 inhabitants of M...
by mfb
Sat Mar 25, 2017 9:27 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1815: "Flag"
Replies: 49
Views: 3477

Re: 1815: "Flag"

Sableagle wrote:
mfb wrote:The official time of the country shall be 5:48 PM.

GMT - 6 hours and 12 minutes, to annoy everybody?
No, that would change.

The time zone is dynamic, it is GMT+(17:48-GMT). To always have 5:48 PM local time.
by mfb
Fri Mar 24, 2017 5:25 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1815: "Flag"
Replies: 49
Views: 3477

Re: 1815: "Flag"

The official time of the country shall be 5:48 PM.
by mfb
Mon Feb 20, 2017 9:58 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1801: "Decision Paralysis"
Replies: 29
Views: 2832

Re: 1801: "Decision Paralysis"

Take the left car. You won't get into the right car at the driver's side.
Unless this is in the UK, then take the right car.
by mfb
Sat Jan 28, 2017 4:06 pm UTC
Forum: News & Articles
Topic: The Thread To Remind Me We're Living In The Future
Replies: 1369
Views: 172850

Re: The Thread To Remind Me We're Living In The Future

The publication seems to be based on the reflectivity as main indicator, but there are other options that could explain it.

Here is an article at nature.com questioning the claims.

Looks like whatever they had didn't survive the depressurization, nothing about that is mentioned in the publication.
by mfb
Fri Jan 27, 2017 12:19 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1002: "Game AIs"
Replies: 240
Views: 60138

Re: 1002: "Game AIs"

I, for one, welcome our new robot overlords. Anyone know how the best poker bots are performing these days? I know starcraft AIs are still hopeless against humans. I think computers do well in heads up poker, but in a contest a year ago humans still won. Computers will probably beat us at that soon...
by mfb
Tue Jan 17, 2017 1:13 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0893: "65 Years"
Replies: 210
Views: 48135

Re: 0893: "65 Years"

Astronauts have better than average healthcare and they were selected for not having any health problems when they became astronauts. I don't know if the graph takes that into account. 6 left: Harrison Schmitt, 81 Charles Duke, 81 David Scott, 84 Alan Bean, 84 John Young, 86 Buzz Aldrin, 86 <- will ...
by mfb
Fri Nov 18, 2016 9:31 pm UTC
Forum: Science
Topic: Expected oldest person in history
Replies: 33
Views: 5535

Re: Expected oldest person in history

Gaussian? Where do you expect a Gaussian? The distribution looks like an exponential decay.
Eebster the Great wrote:The fact that Calment lived so long suggests the distribution is not Gaussian
It is very weak evidence. A constant ~2/3 per year mortality is perfectly compatible with a single person reaching 122.
by mfb
Sat Oct 08, 2016 12:19 pm UTC
Forum: Science
Topic: Expected oldest person in history
Replies: 33
Views: 5535

Re: Expected oldest person in history

A recent study (NY times) suggests that 115 (+- a few years) is an upper limit on the human lifespan, and that Jeanne Calment was a huge outlier, with a probability of at least one person reaching 125 below 1/10000.
by mfb
Mon Jun 06, 2016 6:41 pm UTC
Forum: Science
Topic: Expected oldest person in history
Replies: 33
Views: 5535

Re: Expected oldest person in history

I wonder about this specific point. For example: Jeanne Calment's hip surgery at 114 seems to have been her first encounter with modern medicine. Up to that point, she was just healthy and didn't need much medical care at all. She might have enjoyed indirect benefits, from cleanliness standards or ...
by mfb
Mon Jun 06, 2016 6:15 pm UTC
Forum: Logic Puzzles
Topic: Escape the Frictionless Circle
Replies: 136
Views: 20706

Re: Escape the Frictionless Circle

Momentum is still perfectly conserved in special relativity.
Also, the block flies apart long before you reach relativistic velocities. Also, you fly apart long before the block does.
by mfb
Mon Jun 06, 2016 6:14 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1690: "Time-Tracking Software"
Replies: 29
Views: 4305

Re: 1690: "Time-Tracking Software"

Alt text: 'List of helicopter prison escapes' and 'List of sexually active popes' are both entertainingly long, but sadly there's no 'List of helicopter prison escapes involving sexually active popes.' Needs a time-tracking software. The last potentially sexually active pope in the list (!) died 18...
by mfb
Thu May 19, 2016 7:17 pm UTC
Forum: Science
Topic: Expected oldest person in history
Replies: 33
Views: 5535

Re: Expected oldest person in history

I wouldn't trust all those unverified claims . Assuming the verification of the birth date is not related to the age reached (for 114+), we can use the confirmed list to estimate death rates, and see if the unconfirmed cases have the same distribution. Longer tails there would be a strong indication...
by mfb
Thu May 05, 2016 12:04 am UTC
Forum: Science
Topic: Engines big enough....
Replies: 28
Views: 4080

Re: Engines big enough....

But we can't magically generate additional continents to launch, on any timescale. Earth does that naturally over geological timescales. A space elevator provides a way to launch stuff to space without wasting energy if you find some clever way to store and redistribute energy over the trip well be...
by mfb
Wed May 04, 2016 11:50 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1676: "Full-Width Justification"
Replies: 64
Views: 9365

Re: 1676: "Full-Width Justification"

&nbsp; = non-breaking snake's place
by mfb
Sun Feb 21, 2016 12:39 am UTC
Forum: Logic Puzzles
Topic: Escape the Frictionless Circle
Replies: 136
Views: 20706

Re: Escape the Frictionless Circle

@jasondrake: That approach is so much easier: Go to one side of the block. You are probably warmer than the block. You emit radiation roughly isotropically, but the block will absorb some part and emit it isotropically again. In total, you get a bit of net thrust, and you move (block first)....
by mfb
Sun Feb 21, 2016 12:32 am UTC
Forum: What If?
Topic: What-If 0145: "Fire From Moonlight"
Replies: 157
Views: 24413

Re: What-If 0145: "Fire From Moonlight"

And if Randall's numbers are correct, that the lunar irradiance is 1/400,000 that of the sun, then yes indeed a lens 400,000 times the size required by a solar one would work as far as I'm concerned. It does not, as the what-if describes, and has been pointed out numerous times in this thread now. ...
by mfb
Sat Feb 20, 2016 8:25 pm UTC
Forum: Science
Topic: Engines big enough....
Replies: 28
Views: 4080

Re: Engines big enough....

Every rocket leaving Earth orbit alters the orbit of Earth. That's about 50 probes so far, with a typical mass of a few tons each. Let's say they all all had a mass of 5 tons (optimistic) and all left with 5 km/s in the same direction (very unrealistic). That gives a total speed change of Earth of 0...
by mfb
Sat Feb 20, 2016 8:14 pm UTC
Forum: Science
Topic: is Chicago ever the "front" of the planet?
Replies: 30
Views: 4509

Re: is Chicago ever the "front" of the planet?

At the day of an equinox, the point that is "the front" (in heliocentric coordinates) is at a latitude of +- 23.5 degrees. At the summer and winter solstices, it is at the equator. In between, it is in between. If you are at 23.5° N or S and "at the front", 3 months later you hav...
by mfb
Sat Feb 20, 2016 2:48 pm UTC
Forum: Logic Puzzles
Topic: Escape the Frictionless Circle
Replies: 136
Views: 20706

Re: Escape the Frictionless Circle

@Jeff_UK: You cannot start such an orbit, unless you spin in the opposite direction very fast (or let the block spin). But it would not help, conservation of momentum (both linear and angular) is still exact in special relativity.
by mfb
Sat Feb 20, 2016 2:46 pm UTC
Forum: Science
Topic: Problems in medical research:Tracking outcome switching
Replies: 90
Views: 7432

Re: Problems in medical research:Tracking outcome switching

The fact that it happens frequently in some scientific disciplines doesn't make it better. It does not happen in particle physics, for example. Probably because particle physics requires multi-million dollar machines be built, that takes potentially a decade and involves hundreds of researchers. Wh...
by mfb
Wed Feb 17, 2016 11:53 pm UTC
Forum: Science
Topic: Problems in medical research:Tracking outcome switching
Replies: 90
Views: 7432

Re: Problems in medical research:Tracking outcome switching

'Cheap in comparison' does not remotely mean 'cheap'. Yes, but it is like throwing a new car away because you would have to buy a steering wheel to use it. If you are fine with "just making it public" instead of a peer-reviewed publication, it is even cheaper (just the costs of writing th...
by mfb
Wed Feb 17, 2016 11:47 pm UTC
Forum: Science
Topic: LIGO Gravity Waves: Questions and Answers
Replies: 49
Views: 5768

Re: LIGO Gravity Waves: Questions and Answers

With the practical caveat that the earlier the waves were generated the more redshift they have and thus the longer they are and thus the longer your detector needs to be. With, presumably, no upper bound. And face it, when you need a detector of mutiple light years long then you're going to have v...
by mfb
Wed Feb 17, 2016 11:45 pm UTC
Forum: What If?
Topic: What-If 0145: "Fire From Moonlight"
Replies: 157
Views: 24413

Re: What-If 0145: "Fire From Moonlight"

A parabolic mirror, with the flammable bit in the focus point would probably be more efficient, yeah. You'd just need a horribly large one, because the moon is a crappy reflector. Pretty much any solar stove design scaled up to ridiculous degrees should suffice. It does not, for reasons explained b...
by mfb
Tue Feb 16, 2016 10:33 pm UTC
Forum: Science
Topic: Problems in medical research:Tracking outcome switching
Replies: 90
Views: 7432

Re: Problems in medical research:Tracking outcome switching

While I totally agree that a null result is valuable information, science does not happen in an academic vacuum. Try to think about it from an economic perspective for example. In most cases a positive result has a far better likelihood to lead to some way to make money from it. In the eyes of the ...
by mfb
Tue Feb 16, 2016 9:43 am UTC
Forum: Mathematics
Topic: Combinatorics : Castle, rooms and doors
Replies: 14
Views: 2332

Re: Combinatorics : Castle, rooms and doors

Yeah, just figured that out as well.
Was confused by the odd 3, but once you consider a "direction", it works nicely.

An interesting connection.
by mfb
Tue Feb 16, 2016 12:24 am UTC
Forum: Mathematics
Topic: Combinatorics : Castle, rooms and doors
Replies: 14
Views: 2332

Re: Combinatorics : Castle, rooms and doors

I tried to make a connection between 3-colorings and doors, using the colors at the corners and the vertices between the colors as walls. The numbers match but I don't see an intuitive connection yet.
by mfb
Tue Feb 16, 2016 12:20 am UTC
Forum: Science
Topic: Problems in medical research:Tracking outcome switching
Replies: 90
Views: 7432

Re: Problems in medical research:Tracking outcome switching

Outside of a purely academic context null results are in most cases not equally useful. Finding that drug X can cure Y is much more useful than finding that it can't. It is a more desirable result, but the use of the study is the test of the drug. If it is positive: great. If it does not have a mea...
by mfb
Tue Feb 16, 2016 12:16 am UTC
Forum: Science
Topic: LIGO Gravity Waves: Questions and Answers
Replies: 49
Views: 5768

Re: LIGO Gravity Waves: Questions and Answers

Gravitational lenses are not things lensing gravity waves, they are gravity lensing the light from a distant object. They are lensing gravitational waves in the same way. They are lensing everything massless in the same way. Because the gravitational waves emitted from the big bang 13.82 billion li...
by mfb
Tue Feb 16, 2016 12:03 am UTC
Forum: Science
Topic: "Miracles" of science idea for a XKCD panel
Replies: 6
Views: 1965

Re: "Miracles" of science idea for a XKCD panel

This article is relevant to the topic: http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html It explains how GPS would be totally broken if we did not know about general and special relativity. The article gets it completely wrong. The numbers there would be true if you would compare the...
by mfb
Sun Feb 14, 2016 1:20 pm UTC
Forum: What If?
Topic: What-If 0145: "Fire From Moonlight"
Replies: 157
Views: 24413

Re: What-If 0145: "Fire From Moonlight"

A rock in a crater on the moon has moonlight hitting it from a good portion of its viewlines (say 25%) and it exposed in that fashion for about 2 weeks at a time.(It is also exposed to sunlight, but that just make the argument stronger) It gets heated to about 100 degrees F. So that is an upper bou...
by mfb
Sun Feb 14, 2016 12:15 pm UTC
Forum: Science
Topic: LIGO Gravity Waves: Questions and Answers
Replies: 49
Views: 5768

Re: LIGO Gravity Waves: Questions and Answers

Lasers bouncing between mirrors attached to the end of fixed rods might be able to detect a passing wave, but the signal would be weaker than if the mirrors are not constrained. In LIGO, they are not constrained. The speed of sound is of the order of kilometers per second or less, with the ~100 Hz ...

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