Built on Facts

William Gibson revolutionized the world of science fiction with his dark and gritty but somehow impossibly cool cyberpunk novel Neuromancer. Dystopias have always been a staple of science fiction, but in this case the dystopia didn’t seem too horribly dystopic. Sure some computer might try to take over the world or some vat-grown ninja might shiv you in a space station, but it would sure be an interesting life even if it was short and weird. Gibson’s skill with language helped. The first line of the novel resonates in fiction circles to this day:

The sky above the port was the color of television, tuned to a dead channel.

Neuromancer was written in 1984. I think it’s a little funny that in the modern world of digital TV the color of a television tuned to a dead channel is in fact a solid bright blue. It’s probably not a coincidence. If your TV is showing a dead channel there’s probably something wrong with it. And if it’s broken, the manufacturer probably can guess that you don’t want to be looking at some frustrating color like red. If you’re going to be calling their support department you should probably have a nice blue sky in mind.

The sky itself blue due to the scattering action of the atmosphere. Carrying the explanation beyond that is something we’ll save for later, but for now it’s good enough to say that it is in fact the atmosphere that’s doing the scattering.

This is from the Wikipedia article on the sky, and you’ll notice that at this high altitude the blueness gets deeper and at high angles you have even less total atmosphere to do the scattering and so the blueness fades to black. So just how much atmosphere have you managed to get above at airline altitudes? Most of it. The cabin is pressurized for a reason.

The barometric formula gives a pretty good estimate of exactly how much. At typical airline altitudes you’re above more than 2/3 of the atmosphere. If you’re sufficiently clever you could estimate your altitude by judging how dark the blueness of the sky was. It wouldn’t be easy or very accurate, but you could do it.

I don’t fly often, but when I do I notice that most people keep their windows closed and do something boring like sleep the whole way. I think it’s a better idea not to do that. Open the window and take a look, and see what you can notice about this ocean of air we inhabit.

Comments

#1 Anonymous
November 7, 2008

“Necromancer was written in 1984″? 3rd paragraph.
Freudian slip? I always thought you physics geeks were a little weird.

Seriously ‘though… Thank you for your blog — I love and am amazed at the amount of work you seem to put into it (even if I am a liberal Dem).
#2 Chad Orzel
November 7, 2008

I think it’s a little funny that in the modern world of digital TV the color of a television tuned to a dead channel is in fact a solid bright blue.

Neil Gaiman riffed off this in his novel Neverwhere
(Chapter 20, second paragraph), writing “The sky was the perfect untroubled blue of a television screen tuned to a dead channel.”
#3 Eric Lund
November 7, 2008

I don’t fly often, but when I do I notice that most people keep their windows closed and do something boring like sleep the whole way.

I think you mean that people keep their window shades down–for obvious reasons you cannot open an airplane window.

Often the window shades are down because flight attendants insist on it. They think we’re eager to pay $5 to watch a mediocre movie or something. I agree that most such passengers are missing out on a good show. One of my games is to look down (if in daylight and skies are clear to partly cloudy) and try to figure out where I am. Mostly I have to work that out from roads and rivers, but not always–e.g., it’s easy to spot the Nebraska-Colorado border from the air if you know what to look for.
#4 Chris
November 7, 2008

I only put the shade down when there’s blinding light reflecting from the clouds.
#5 Eugene
November 7, 2008

I’m reminded of an On the Media story from January 2005 about the (mostly) dead technology represented by the “record scratch” sound effect. The intrepid reporter had no problem finding kids who couldn’t identify the needle-on-vinyl source of the sound. But like a colloquial expression whose etymology has been lost in the mists of time, everybody still knows what the record scratch “means.”
#6 Matt Springer
November 8, 2008

Thanks, #1!

Chad, that’s almost too bad. I thought I had a clever original observation! Oh well, if I’m going to be scooped it might as well be by Gaiman.
#7 Derek
November 9, 2008

Short time reader, first time commenter.

I was unaware of this book, but the premise seemed neat and I love dystopias, so I looked into it.

The end of the first chapter reads, “the neon dead, the holograms inert, waiting, under the poisoned silver sky.” That’s all the further I’ve gone into the book, but is it possible you attributed the wrong color? He talks a bit there about Styrofoam floating around in the sea; it’s more likely the sky would be swirling smoke.

But, you’ve apparently read the whole book – I have not. Either way, great blog, great post, thanks for turning me on to what will likely be a great book.
#8 Ryan
November 11, 2008

In 1984,the colour of a dead TV channel was that fuzzy snow type thing with all the grey and white dots buzzing araound, and the white nooise in the background. They didn’t have any digital blue channels or anyting like that.