93 stories · 2 followers

## Phone Numbers Monday January 23rd, 2017 at 3:55 PM

popular
123 days ago
wreichard
121 days ago
Earth
toddgrotenhuis
122 days ago
me IRL
Indianapolis
Brstrk
123 days ago
#4 is for whenever I have to enter a number and think I'll be bombarded with robocalls, unless the call starts with a magic package, in which case it's forwarded to my laptop to wake it up.
Covarr
123 days ago
Moses Lake, WA
tsuckow
122 days ago
chrisrosa
123 days ago
this in a nutshell
San Francisco, CA
CallMeWilliam
123 days ago
voicemail is terrible.
alt_text_bot
123 days ago
Texting should work. Unless the message is too long, in which case it gets converted to voicemails, and I think I'm locked out of my voicemail.
123 days ago
You're my new favorite bot.
Aissen
123 days ago
@adam8797 Author here. Glad you like it! I forgot it was still running ! You probably don't need it anymore since on mobile you can long press images to see the alt text now.
samuel
122 days ago
Heh, this is a great bot. Keep it!
Aissen
121 days ago
@samuel I have no intention to stop it for now, it just runs itself :-)

## Life Goals Tuesday October 25th, 2016 at 3:59 PM

popular
211 days ago
Brstrk
213 days ago
- Learn to cast Xyzzy
Covarr
213 days ago
play SimCity 2000 without using the "porntipsguzzardo" cheat code.
Moses Lake, WA
zippy72
213 days ago
I never knew that existed. Now I will have to see if I can find a Sim City 2K disk again and try it out :)
ryanbrazell
213 days ago
I take issue with the last one ... you're not really trying if you're not getting punched.
Richmond, VA
alt_text_bot
214 days ago
I got to check off 'Make something called xkcd' early.

## Coffee Sunday October 9th, 2016 at 8:08 AM

Covarr
229 days ago
Step 1: Go to starbucks
Moses Lake, WA
Brstrk
229 days ago
Oh. So that's why my workplace's coffee taste funny.
rtreborb
229 days ago
If I had to count the number of times someone gasped when I mentioned I don't drink coffee...
tedder
231 days ago
Uranus
darastar
231 days ago
This is me. I'm not a coffee drinker and feel awkward trying to make it.
foilman
231 days ago
Same here! Luckily there's usually someone around who knows what they're doing.
Cthulhux
231 days ago
This must be fake, there's no hilarious amount of caramel in it.
Fledermausland
231 days ago
I guess this is why those god-forsaken coffee pod abominations are a thing.
Los Angeles, California, USA
alt_text_bot
231 days ago
Remind me to order another pack of coffee filters from Dyson. Man, these things are EXPENSIVE.

## Work Monday October 3rd, 2016 at 5:00 PM

wreichard
234 days ago
This goes along with one of what I think of life's best hidden lessons: if you assume that things around you are the way they are for some reason, you learn amazing things.
Earth
brico
234 days ago
A curiously bureaucratic and teleological vision from Randall; I look at these and see evolution, not design. The gooseneck lamp goes back well over a century. And the glass tumbler and the wooden table with aprons are even older forms.
Brooklyn, NY
Brstrk
235 days ago
No mention on any documentation processes. Some heroes just go unsung.
duerig
235 days ago
He missed designing for manufacturability. "This shape was chosen because it is easy to stamp out of sheet metal." or "These two parts snap together in order to eliminate two screws."
duerig
235 days ago
Also, I found out how they make plastic soda bottles recently. First, a test-tube shaped piece of plastic is cast. Then before it has cooled, they stick it at the opening of a mold and blow air through it until the sides conform to the shape of the mold. For large bottles (2-liter), they have a rod that automatically pushes the bottom of the tube down deeper into the mold as air is blown in. It is like automated glassblowing with plastic, done countless times over and over for a disposable bottle.
infini
235 days ago
supernormal design as jasper morrison and naoko fukusawa would call it
Asia, EU, Africa
dukeofwulf
235 days ago
Related: "I, Pencil." http://www.econlib.org/library/Essays/rdPncl1.html
Covarr
235 days ago
An artist spent several minutes deciding what objects to put on this table.
Moses Lake, WA
ossiander
235 days ago
I could see this.
magicseth
235 days ago
On point
mburch42
235 days ago
My life.
reconbot
235 days ago
Truth behind objects
New York City
alt_text_bot
235 days ago
Despite it being imaginary, I already have SUCH a strong opinion on the cord-switch firing incident.

## Politifact Wednesday July 27th, 2016 at 2:08 PM

Brstrk
303 days ago
Sometimes I want to see some strips acted out in live-action. Can you imagine how silly politifacts could be?

Also, this: http://xkcd.com/585/
Covarr
303 days ago
Time for an all out war between PolitiFact and Snopes.
Moses Lake, WA
chrisamico
303 days ago
That thing where a site built by your friends ends up in XKCD.
Boston, MA
cbenard
303 days ago
#humblebrag
wreichard
303 days ago
Truth.
Earth
alt_text_bot
303 days ago
"Ok, I lit the smoke bomb and rolled it under the bed. Let's see if it--" ::FWOOOSH:: "Politifact says: PANTS ON FIRE!"

# Sun Bug

How many fireflies would it take to match the brightness of the Sun?

Luke Doty

Not that many! I mean, it's definitely one of those gigantic numbers with lots of zeroes, but in the grand scheme of things, there aren't as many zeroes as you might expect.

Our first question: Where does firefly light even come from?

Fireflies may look like they're full of glow-in-the-dark goo, but the light they give off actually comes from a thin layer on their surface.[1]You can see some diagrams of the organs here and here. Lots of insects have glowing surface patches, and some of those patches have been studied carefully to calculate their brightness. A 1928 paper on beetles called "headlight bugs"[2]Such a great name. found that their glowing patches, which were a little over a square millimeter in area, emitted about 0.0006 lumens of light. Fireflies have luminous organs (bright patches) that are about the same size as those of headlight bugs,[3]See this paper on some common American fireflies. and their organs tend to have a similar peak brightness per area, so this figure is a good guess for the brightness of a firefly's lantern.

Firefly lights aren't "always-on." They blink on and off, with patterns that vary from species to species and situation to situation. These flashes carry information, some of which you can decode using this delightful chart.[4]You can also use LEDs to mess with firefly patterns, which feels strangely invasive.

To get the brightest light, let's assume we're using a species with a mostly-on duty cycle—like a headlight bug. How does its 0.0006-lumen light output compare to the Sun?

The Sun's brightness is $$3.8\times10^{28}$$ lumens, so by simple division, it would take $$3\times10^{31}$$ of those fireflies to emit the same amount of light. That's a surprisingly small number; adult fireflies weigh about 20 milligrams, which means $$3\times10^{31}$$ fireflies would only weigh about a third as much as Jupiter and 1/3000th as much as the Sun.

In other words, per pound, fireflies are brighter than the Sun. Even though bioluminescence is millions of times less efficient than the Sun's fusion-powered glow, the Sun can't afford to be as bright because it has to last billions of times longer.[5]If you like Fermi problems—and silly equations—there's an interesting route you can take to this answer without doing any research on fireflies or the Sun at all. Instead, you can just plug this equation into Wolfram|Alpha: (5 billion years / (4 hours/day * 3 months)) / (1% * (speed of light)^2 / (3200 calories/pound)).

Let's walk through it: The first half—the numerator—is a guess for the ratio between how long the Sun has to keep glowing compared to how long a firefly does. I took a wild guess that fireflies have to light up for a few hours each night for one summer, while the Sun has to last another five billion years. The second half—the denominator—is a guess as to the ratio between the stored energy in a pound of firefly vs a pound of star. Nuclear fusion converts about 1% of the input matter to energy, so from E=mc2, the stored energy is c2 kg/kg, whereas animal matter (say, butter) is about 3,200 food calories per pound. The result should tell us the ratio between a firefly's brightness per pound and the Sun's. And the answer we get says that the fireflies are a few thousand times brighter—which is roughly what we got from working through it the other way!

It's true that we got lucky with some of our guesses, but since we made errors in both directions, they tended to cancel out. This kind of thing works more often than it seems like it should!

But wait! A mass of fireflies that big would run into problems. Besides the obvious problems with gathering that many animals in one place, the fireflies would block each others' light. The inner fireflies would be hidden behind the outer ones, and the total brightness would be limited.[6]But the light from the core fireflies wouldn't just vanish. After bouncing around a few times, it would be absorbed by neighboring fireflies, which would get warmer. This is sort of like how radiation makes its way out of the Sun's core—but in the case of the fireflies, they'd die from the heat before the process got very far.

Since the only light that matters is the light at the surface, we could imagine arranging the fireflies in a hollow sphere, with their lanterns pointing outward. Or, to make thing simpler, we could imagine a single giant firefly. How big would it need to be?

Since we know our firefly will need to give off about $$3\times10^{31}$$ times as much light as a normal firefly, it will need a glowing patch $$3\times10^{31}$$ times larger. Since surface area is proportional to length squared, our firefly will have a body length $$\sqrt{3\times10^{31}}=5\times10^{15}$$ times longer than a normal firefly, which would make it about the size of the Solar System.

Since mass is proportional to length cubed, our firefly would weigh $$\left( 3\times10^{31}\right)^{\tfrac{3}{2}}=1.6\times10^{47}$$ times as much as a normal firefly, which works out to about half as much as the entire Milky Way galaxy.

Such a firefly would immediately collapse under its own weight and become a black hole. In fact, given the distribution of galaxies in our universe, there's an upper limit to how large black holes can grow, and this firefly would be bigger than that limit. That means our firefly would become the largest black hole in the universe. It would give off a lot of light as it devoured our galaxy, and then, eventually, it would give off none at all.

Black holes last a long time, but they eventually evaporate through Hawking radiation. When the black hole era of our universe comes to an end, black holes will evaporate one by one, with the smallest evaporating faster. Since our firefly's black hole would be the largest one in the universe, it would be the last to evaporate—a final outpost of irregularity in a universe fading toward heat death.

We should probably add that to the identification chart, just in case.

popular
310 days ago