Tag Archives: xkcd

Beam me up… how many lasers would it take to take down the moon

XKCD‘s Randall Munroe is, I reckon, the smartest guy on the Internet. Hands down. His What If Blog continues apace, and continues to blow my mind with its diversity.

If you want your mind blown – check out this comic called “Drag” from a couple of weeks ago.

Today he’s hypothetically putting a laser dot on the moon – turns out it’s pretty difficult, and doing it properly will have some deadly results…

Make sure you find out what led to this point…

Ok, let’s mount a megawatt laser on every square meter of the surface of Asia. Powering this array of 50 trillion lasers would use up Earth’s oil reserves in approximately two minutes, but for those two minutes, the Moon would look like this:

a field of megawatt lasers covering asia fires at the moon

The Moon shines as brightly as the midmorning sun, and by the end of the two minutes, the lunar regolith is heated to a glow.

a man in a hat suggests trying more power.

Ok, let’s step even more firmly outside the realm of plausibility.

The most powerful laser on Earth is the confinement beam at the National Ignition Facility, a fusion research laboratory. It’s an ultraviolet laser with an output of 500 terawatts. However, it only fires in single pulses lasting a few nanoseconds, so the total energy delivered is about equivalent to a quarter-cup of gasoline.

Let’s imagine we somehow found a way to power and fire it continuously, gave one to everyone, and pointed them all at the Moon. Unfortunately, the laser energy flow would turn the atmosphere to plasma, instantly igniting the Earth’s surface and killing us all.

Also, check out what happens if the population of the world rocks up at Rhode Island and all jump at the same time.

Also, just for fun… there’s a really small paragraph of text on the XKCD home page that reads:

We did not invent the algorithm. The algorithm consistently finds Jesus. The algorithm killed Jeeves.
The algorithm is banned in China. The algorithm is from Jersey. The algorithm constantly finds Jesus.
This is not the algorithm. This is close.

Here’s the fun answer about why it’s there.

How to hit a baseball travelling at the speed of light

It seems obvious that you can’t do this. XKCD does the math (or physics) to demonstrate that not only is it impossible, it’s also fatal for pitcher, batter, and probably the entire city…

“After about 70 nanoseconds the ball arrives at home plate. The batter hasn’t even seen the pitcher let go of the ball, since the light carrying that information arrives at about the same time the ball does. Collisions with the air have eaten the ball away almost completely, and it is now a bullet-shaped cloud of expanding plasma (mainly carbon, oxygen, hydrogen, and nitrogen) ramming into the air and triggering more fusion as it goes. The shell of x-rays hits the batter first, and a handful of nanoseconds later the debris cloud hits.”

mushroom cloud

It’s not all bad news though. The batter gets on base.

A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered “hit by pitch”, and would be eligible to advance to first base.

I love this stuff. The XKCD “What If” blog is tackling similar questions on a weekly basis. Like trying to figure out how much power Yoda could generate via the Force.

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YouTube Parties: Social gatherings 2.0

YouTube Parties. Have you been to one? Some dinners at our place in recent times have turned into such occasions. Especially because of the awesome power of the Apple TV… Anyway. At a YouTube party each guest shares one of their favourite YouTube clips hoping that it’s new and mind blowing. It’s pretty much the reason I blog. And it’s the reason you should send me any terrific clips you come across. Because I wouldn’t want to lose any of my 2.0 street cred.

Anyway. XKCD demonstrates the tension beautifully.

So. Got anything good to share? Lets have a Social Gathering 2.0 2.0. A virtual meeting of the minds. A sharing of treasures.

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On wikipedia philosophy really is the starting point of knowledge

One of the things I’m increasingly realising as I engage in more critical interaction with people’s thoughts (particularly in scholarship, but also on the Internet and in person) is that it is one’s presuppositions, or philosophical framework, that produces one’s conclusions. It’s true in just about all areas and it’s one of the reasons (essentially operating alongside confirmation bias) that trying to change people’s minds online is entirely pointless.

You can take almost every conclusions somebody draws about the world back to that underlying framework. So you’d expect to see this born out in the way articles are linked in wikipedia (the web of interlinked connections between articles in wikipedia is, in my opinion, the most useful thing about it). And you do. According to this new webapp thingo by Xefer. Which illustrates the truth that all articles will eventually link to Philosophy. Which is kind of like my fairly ancient game 6 Degrees of Wikipedia.

“This sounded like a reasonable assertion, one that makes a certain amount of sense in retrospect: any description of something will typically use more general terms. Following that idea will eventually lead… somewhere.”

Like everything good on the Internet,this concept began in the hovertext of an XKCD comic.

Via FlowingData

Life imitates webcomic

Somewhere in my archives there’s a story about people putting the ideas put forward by XKCD into some sort of real life application. Well. Here’s another example (previous examples include adults filling their lounge room with colourful balls to make their own ball room).

Somebody did this. And you can follow the progress of the eBay robot on Twitter, and read about the source code here with an update here

  • It runs every day at 8pm (although it was earlier today because I was testing it)
  • It gains $1 every day, and has a 1 in 3 chance of buying an item on any particular day. This means that it will save up money to buy some (slightly) more expensive items.

The method it uses to select items:

  • It has a bunch of top-level categories it looks in.
  • For each of these categories, it searches for the term “Free shipping”, specifying both pay-now and buy-now, sorting by newest listings, with a maximum of 100 items returned per category.
  • For each of these items, it filters on buy-now price. It tries to spend at least 50% of its savings.
  • For each of the surviving items, it looks up the individual auction details to find its shipping information so it can filter on free shipping. Despite searching for the term ‘free shipping’ to start, only a small number of items have this.
  • At this point I have a list of items that match the price requirements, and can be bought with a credit card buy-now.
  • I then sort this list by ‘rarity’ – doing a search for the item title, and finding the item that returns the least results. As the objective here is to buy strange and esoteric things, rarity is preferred.
  • Finally I buy the rarest item and subtract its cost from the bots savings.

Sounds fun, right? The guy responsible made a couple of changes yesterday:

  • It now tries not to buy in categories it’s bought from before. No more stamps! (probably)
  • It biases towards auctions with more expensive shipping costs – If you check out the trademe listings, you’ll see there’s quite a lot of items for $1-2, but the more interesting things typically have higher shipping.
  • The ‘only bid every 3 days’ rule is gone. Now it will wait until it has at least 20 items that it can possibly buy before making a bid. This is strongly dependent on how much money it has, so it should come to about the same thing.


So far he’s bought some watch batteries, some stickers, and a casio watch. Hooray.

Sticking around: the disproportional impact of a stick figure cartoon

I <3 XKCD. It’s my regular dose of geeky humour rendered in high definition stick figurey goodness. Millions of other people like it too. In fact, XKCD is arguably the world’s most influential blog. The forum 4Chan might cause more havoc, but XKCD readers tend to use their powers for good. Remember Tetris Hell? That was an XKCD comic. Within hours a reader had made it playable.

In this comic ninjas visit an open source software guru:

Shortly afterwards… ninjas confronted the guy at a conference.

After this comic:

This guy created a ball room in his house using this calculator that another reader created.

Here’s an article tracking XKCD’s influence.