Harder Drive: Hard drives we didn't want or need (2022) [pdf] | Hacker News Reader

Harder Drive: Hard drives we didn't want or need (2022) [pdf]

tom7.org

98 pointsa02231125 comments

There's a fantastic associated YouTube video that talks through these too: https://www.youtube.com/watch?v=JcJSW7Rprio

It's a rabbit hole that had be fascinated for quite a while.

For those who might not be aware, early computer memory relied on essentially the same principle:

https://en.wikipedia.org/wiki/Delay-line_memory

I have a crazy idea. The round trip travel time of light to the moon and back is about 3 seconds, and we did leave a mirror up there. At modern modulation rates and with multiple frequencies of light in use at the same time (aka different color lasers), a lot of data can fit into that 3 second window.

A memory made of the vacuum of space. The lightest hard drive ever.

Sure. You can also do radio moonbounce, which radio hams routinely do.[1] About 2.5 secs of lag. It takes a sizable antenna. You could probably use that as a delay line. Noisy, so error correction will be necessary.

Laser moonbounce is harder to do than radio.[2] Early systems used so much laser power that they had to be equipped with radars to turn the system off if aircraft were in the area. Later systems with safer lasers could detect single photons with a 40cm telescope and transmit a 2KHz signal.

[1] https://en.wikipedia.org/wiki/Earth%E2%80%93Moon%E2%80%93Ear...

[2] file:///home/john/Downloads/SLR2000_Eyesafe_and_autonomous_single_photoelectro.pdf

This seems more like the airplanes problem than my problem...

The judge is unlikely to agree with you.

But I already have an insanity defense, based on the fact I was using the retroreflectors on the moon for data storage.

Would you have a working link to that second PDF?

Here are some SLR2000 papers that are more easily accessible.[1][2]

Doing this with low-power lasers requires rather good receiving optics.

There has been a major breakthrough in laser data transmission - the first cat video has been sent by laser to and from a spacecraft. "At the time, Psyche was traveling 19 million miles (31 kilometers) from Earth, about 80 times the distance between Earth and the Moon. Traveling at the speed of light, the video signal took 101 seconds to reach Earth, sent at the system’s maximum bit rate of 267 megabits per second."[3]

[1] https://ilrs.gsfc.nasa.gov/lw15/docs/papers/SLR2000,%20The%2...

[2] https://ilrs.gsfc.nasa.gov/lw13/docs/presentations/adv_degna...

[3] https://arstechnica.com/space/2023/12/a-cat-video-highlighte...

Radio link?

Being the moon is not geostationary this doesn't seem very useful.

Also between atmospheric distortion and dust/micro meteorites you'll going to need to be very careful on your error encoding choices.

No spoilers, but I think you would enjoy this short story: https://qntm.org/transi

"The same principle" as the first of the harder drives. There are several drives presented.

Dupe of https://news.ycombinator.com/item?id=30974165

Tom7 content deserves being posted every day though.

Wish Lorem Epsum became a real phrase as well.

Epsum didn't lorem self.

I think this is a candidate for best two sentence combo ever written:

So we have 1 million chainsaws per second, for 335.36 hours, which is 1.215 × 10^12, a configuration known as tera-wield. This requires expert juggling skills.

The straightfaced and unhinged nature of the chainsaw section reminds me of Hitchhiker's Guide to the Galaxy, and probably some Kurt Vonnegut stuff. I love this style of writing.

I would nominate this one

> Tetris is an inventory-management survival-horror game with 19 principal characters, each with its own story arc

Not a 2 sentence combo. Also, for the confused, there are 19 characters if you consider non-trivial rotation to be switching between different characters.

Google calendar fs, using Google calendar to store data in events, was inspired by this. Any others?

it's not directly inspired by tom7, but there's pifs: https://github.com/philipl/pifs

Tom7 is the goat. Love his videos.

Figure 1 is somehow beautiful in it's chaotic dis/organised structure, a representation of the whole internet, something which us humans now so heavily rely on

ipv6 yadda yadda yadda

Nice grapixhs

Reply on news.ycombinator.com