thunk wrote:So what about Portwine Rocky?

It goes an a separate page, along with Gum and the Northern Marinara Islands.

- Fri Dec 02, 2016 11:43 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1767: "US State Names"
- Replies:
**59** - Views:
**10643**

thunk wrote:So what about Portwine Rocky?

It goes an a separate page, along with Gum and the Northern Marinara Islands.

- Sat Nov 26, 2016 2:42 pm UTC
- Forum: News & Articles
- Topic: Where Aren't They Now (Obituaries)
- Replies:
**187** - Views:
**28975**

Angua wrote:Zoboomafoo

But the lemur died two years ago.

- Sat Nov 12, 2016 3:51 pm UTC
- Forum: Mathematics
- Topic: Three externally tangent circles sharing a single point of tangency
- Replies:
**19** - Views:
**4893**

Not exactly answering the last question, but as long as you can say things like: (1) If B is on a shortest path from A to C, and B is also on a shortest path from A to D, then either C is on the shortest path from A to D, or D is on the shortest path from A to C; and (2) If the distance from A to B ...

- Fri Oct 28, 2016 4:50 pm UTC
- Forum: Mathematics
- Topic: Finding a Quadrilateral for N Points
- Replies:
**20** - Views:
**4322**

For N=5, I think it works if we divide into cases based on the number S of sides of the convex hull of the points. For S=5 you should always be able to remove one side and extend two adjacent sides to meet, forming a quadrilateral. A detailed argument could involve the total exterior angles of a pen...

- Fri Jul 29, 2016 3:53 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1713: "50 ccs"
- Replies:
**46** - Views:
**6586**

I was figuring carbon copies.

- Thu Jul 28, 2016 4:27 pm UTC
- Forum: Movies and TV Shows
- Topic: Wander Woman
- Replies:
**71** - Views:
**10090**

Lawrence of Arabia and The African Queen are both WWI movies, although that may not be obvious to everybody. And there must be a slew of WWI aviation movies, going as far back as the 1927 Wings.

- Wed Jul 27, 2016 1:23 pm UTC
- Forum: Science
- Topic: Is the Hyperloop remotely possible?
- Replies:
**62** - Views:
**7205**

If you don't want passenger fatalities in event of cabin pressure loss, and you don't want your passengers to be wearing pressure suits, and you want the tube to be at 1 millibar, you will need to be able to repressurize the tube swiftly and safely. Or at least the segment containing your vehicle. I...

- Tue Jul 26, 2016 2:50 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1708: "Dehydration"
- Replies:
**109** - Views:
**12638**

Do I figure things correctly that nilane looks a lot like molecular hydrogen, that is, H_{2}?

- Fri Jul 22, 2016 11:54 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1710: "Walking Into Things"
- Replies:
**22** - Views:
**4192**

I do like the addition of "sky" to Randall's list: a useful reminder that one doesn't need devices (or collections of paper) to be distracted. I was certainly at risk a few days ago when we had a pretty impressive rai nb ow . Only a double rainbow, not any of the extreme forms mentioned i...

- Wed Jul 20, 2016 5:00 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1708: "Dehydration"
- Replies:
**109** - Views:
**12638**

HES wrote:What tree has a bowl?

A lava tree?

- Mon Jul 18, 2016 4:17 am UTC
- Forum: Science
- Topic: How do satellites not crash into each other?
- Replies:
**94** - Views:
**13064**

Right, but is that also the median in some sense? Let's see. The distance from the Earth on an elliptical orbit increases monotonically from perigee to apogee, and then decreases again. Half of the ellipse is on the Earth side of the minor axis, half on the other side, so the median points should b...

- Sat Jul 16, 2016 1:10 pm UTC
- Forum: Science
- Topic: How do satellites not crash into each other?
- Replies:
**94** - Views:
**13064**

But all those orbits will pass through the same (comparatively small) volume occupied by geostationary satellites every day, right? An inclined, eccentric geosynchronous orbit has to pass through the same altitude as the geostationary satellites, but it doesn't have to do so anywhere near the equat...

- Wed Jul 13, 2016 8:13 pm UTC
- Forum: Mathematics
- Topic: Trisecting an angle
- Replies:
**63** - Views:
**9682**

You mean that formula enumerates all constructible angles. A nonconstructible angle can be trisectable. For example 3*pi/7 is not constructible, but if we were presented with it, we could take its supplement 4*pi/7, and then bisect to get 2*pi/7, and then again to get pi/7.

- Wed Jul 13, 2016 7:37 pm UTC
- Forum: Mathematics
- Topic: Trisecting an angle
- Replies:
**63** - Views:
**9682**

Maybe it is that if an angle x is constructable, but x/3 is not constructible, then x is not trisectable, and that this formula implies that there are many such constructable but not trisectable angles, for example whenever a is not a multiple of 3 and b_{1} is one in the given formula.

- Wed Jul 13, 2016 3:37 pm UTC
- Forum: Science
- Topic: How do satellites not crash into each other?
- Replies:
**94** - Views:
**13064**

Geostationary orbits, written as GEO, should fit in the torus. Geosynchronous orbits, written as GSO, don't need to be equatorial, which is probably why the shell was proposed. But they don't need to be circular, either. Wikipedia mentions an Infrared Space Observatory at a geosynchronous orbit with...

- Mon Jun 20, 2016 12:48 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1696: "AI Research"
- Replies:
**12** - Views:
**3345**

What's "updog"?

(Is it anything like updoc?)

(Is it anything like updoc?)

- Thu Apr 14, 2016 4:29 pm UTC
- Forum: The Help Desk
- Topic: Diagnosing a Dead Dell Inspiron Touchpad
- Replies:
**9** - Views:
**5920**

Have you looked in the BIOS? Sometimes hardware can be enabled/disabled there.

- Wed Mar 16, 2016 3:34 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1655: "Doomsday Clock"
- Replies:
**64** - Views:
**11345**

Before the advent of mechanical clocks, one option taken was to start the reckoning of hours at dawn, and divide the day into twelve hours, and the night also into twelve hours. An hour of day would equal an hour of night only at the equinoxes. It wasn't too hard to make sundials for these hours. Wi...

- Sat Mar 12, 2016 11:51 pm UTC
- Forum: Mathematics
- Topic: does every unit length curve lie inside the semicircle?
- Replies:
**12** - Views:
**3255**

If you use that argument, you can't add the lengths from the two sectors together. Consider the path e-f-g-h defined as follows. Let theta be some small positive angle. Let e = (sin(theta), cos(theta)), f = (-sin(theta),cos(theta)), g = (-sin(theta),0), h = (sin(theta),0). This has a point on each o...

- Sat Mar 12, 2016 7:43 pm UTC
- Forum: Mathematics
- Topic: does every unit length curve lie inside the semicircle?
- Replies:
**12** - Views:
**3255**

I think the reasoning for Cradarc 's Claim 3 is faulty. Yes, the curve has to connect P, Q, and R, but you haven't shown that it has to do it within the sector. I think the following approach works, extending measure 's idea. Let S be a curve of length x. Let a and b be the two endpoints of S. Let R...

- Tue Mar 01, 2016 8:46 pm UTC
- Forum: General
- Topic: ITT: We make xkcd slightly worse.
- Replies:
**8627** - Views:
**1480436**

I think Sableagle is off by six orders of magnitude, converting 6 x 10^{6} g to 4.6 x 10^{12} cm^{3} can't be right for something with a density only slightly greater than water.

- Fri Feb 26, 2016 6:23 pm UTC
- Forum: Mathematics
- Topic: looking for a probability theorem
- Replies:
**3** - Views:
**1659**

Let x_1 and x_2 be independent standard normal random variables (mean 0, variance 1). Let y_1 be another normal random variable, with mean -0.1, variance 1, and y_2 = y_1. Then for all i,k, P(x_i > k) > P(y_i > k). But X = x_1+x_2 is a normal random variable with mean 0, variance 2, while Y = y_1+y_...

- Thu Feb 25, 2016 6:12 pm UTC
- Forum: Mathematics
- Topic: looking for a probability theorem
- Replies:
**3** - Views:
**1659**

I don't know of a general theorem, but you do need to state that the individual x_i are independent, and the individual y_i are independent. Otherwise there are counterexamples.