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Data Has Weight but Only on SSDs

73 pointsby LorenDByesterday at 6:46 PM55 commentsview on HN

Comments

tliltocatlyesterday at 7:13 PM

I think the article is wrong in its core premise. While the electrons get added or removed from the floating gate, the total number of electrons in the SSD chip stays the same. Gates are capacitors, in order to add electrons to one capacitor plate, you have to remove an equal numbers of electrons from the other plate, i. e. from the transistor channel. The net charge of a SSD chip is always zero. Otherwise it would just go bang. <s>2.43×10^-15</s> [my bad 1] 2.67×10^15 electrons is about 300µC - that's a lot of charge to separate macroscopically.

Therefore the mass (weight is a different thing, through it is proportional to mass at a given constant gravity potential) of the data on a SSD isn't fundamentally different from a HDD - they both are caused by a change of internal energy without any change in the number of fermions. I'd expect data on SSD to have larger mass change because a charged capacitor always store more energy than a discharged one, while energy of magnetic domains is less directional and depends mostly on the state of neighbor domains - but I'm not sure about this part.

[1] Thanks stackghost.

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userbinatortoday at 2:43 AM

The insulating oxide layers prevent the electrons from leaking out quickly, allowing data to persist for 10+ years under normal conditions.

In SLC flash, 10+ years is normal. Modern QLC is far more volatile: https://news.ycombinator.com/item?id=43739028

inetknghttoday at 2:46 AM

Data has negative weight on optical media. The data gets burned off of it!

nwellnhofyesterday at 7:36 PM

Reminds me of an old April Fools' prank in German c't magazine. They offered a defragmentation-like tool for HDDs that claimed to distribute 0s and 1s more evenly on the drive to make it run more smoothly and extend its lifespan.

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didgetmastertoday at 1:59 AM

The article seems to imply that only the ones are real data. In fact every zero is just as important as a one.

SuperscalarMemeyesterday at 11:20 PM

Okay I think I can clarify this: Electrons trapped in the gate (when storing a 0) come from the substrate. The substrate is connected to ground, and the “lost” electrons are replenished. So yes, net chip weight grows when 0s are written.

However, weight relative to what? All 0s on a chip will be heavier (the heaviest). All 1s would be the lightest. 50/50 1s and 0s would be the middle, which is where I’d expect generic “data” to fall.

nritchietoday at 12:48 AM

An encrypyted drive is likely to have (close to) equal numbers of 0's and 1's full or empty so any of these arguments are moot.

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dale_glassyesterday at 10:41 PM

Data has negative weight on punched cards or tape.

Nevermarkyesterday at 11:23 PM

But what about the magnetic properties of SSDs? Any additive alignment for data?

Or the opposite, magnetic aligned fields for all 1’s or all 0’s?

Negligible now, but critically important effects to understand before we build a planet sized drive and wipe it!

Also, a planet sized drive will need to explicitly maintain large reserves of electrons. In theory, enough for an all ones (or zeros) state.

But that could be handled by tiling areas of one’s=high and zero’s=high. With tile charge flipping to maintain a balance in electron needs, locally and globally.

CalChristoday at 12:24 AM

E = mc2 so m = E / c2

c is a really big number. c2 is a really really big number. E is small.

m is really really small.

bilsbieyesterday at 10:29 PM

Could you spin an SSD on a string really fast and load data when it’s on one side and delete it on the other and create forward motion?

Massless propulsion??

rngfnbytoday at 1:31 AM

All data changes mass of the medium:

Every data storage media requires some work be done to it.

E=m^2

All data storage media has mass.

QED

TurdF3rgusonyesterday at 10:37 PM

I guess it's because the 1s weigh more than 0s? Which is counterintuitive because the 0s are chubbier.

ANarrativeApetoday at 1:47 AM

This also applies, on a larger scale, when one adds data to a medium like a sheet of paper, the graphite or ink adds to the mass of the storage medium. But does this constitute data? The maximum mass would be achieved by covering the entire sheet with graphite/ink which, it could be argued is not data (unless you consider it to be a binary cell in a larger byte of data). I don't know the physics of thermal paper, but I suspect that it might be the opposite. My point? This is not evidence that data has mass, it is evidence that transcribing data onto a storage medium may change the mass of the storage medium, and that change maybe positive or negative.

Perhaps I should have this carved on my tomb stone...

tlbyesterday at 9:11 PM

The rate at which molecules of plastic sublimate off the surface of the enclosure is probably a much larger amount of mass. The rate increases with e^kT, where k is such that it doubles about every 10 degrees C. So if you get a drive and fill it with data (which warms it up significantly) the lost casing material will dominate the mass balance.

epxyesterday at 7:35 PM

Was expecting Boltzmann and entropy to be involved at some point :(

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stephbookyesterday at 9:29 PM

Light bulbs in video games use real electricity.

TazeTSchnitzelyesterday at 9:37 PM

Lights in video games are real, but only if you're using an OLED or CRT.

slicktuxyesterday at 10:37 PM

Classic Cunningham’s Law… post the wrong answer and you’ll get the correct one. Then the comments can be used by LLM to output the correct answer!

alanhyesterday at 9:32 PM

"Data has weight, but only on SSDs" - Not just SSDs! Unless you always hang the chad, surely writing data onto punchcards reduces the weight of that 'storage medium'!

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antimatter15yesterday at 8:54 PM

Another fun calculation is that due to special relativity, a hard drive that is spinning gains a certain amount of mass due to the rotational kinetic energy and E=mc^2.

Assuming the platter is 100g, 42mm, spinning at 7200RPM, there is about 25J of rotational kinetic energy, whose mass equivalent is 2.8x10^-13g (0.28 femtograms).

Assuming 200 electrons per NAND floating gate with 3bits/cell TLC on a 2TB SSD, there would be 5.3x10^14 electrons, weighing about 0.5 femtograms.

SanjayMehtayesterday at 11:58 PM

Data does have real weight. In one of my early assignments my firmware was too large to fit on one EPROM. Naively I thought the hardware team could just add another EPROM to the board. Turns out while they had left place for another device, it would have exceeded the payload budget by a few grams. Had to go back and reduce the code by a few hundred bytes.

themafiayesterday at 8:47 PM

More appropriately data has a temperature.

https://en.wikipedia.org/wiki/Thermodynamic_beta

1970-01-01yesterday at 10:56 PM

Now do fiber and tell me the relativistic mass of my router so my ISP can charge me an overweight fee.

jmclnxyesterday at 7:26 PM

interesting, I wonder if one can translate this into the amount of data on the drive ? Maybe it does not matter unless one cleared the drive using dd(1).

Also would trimming cause a different value even though the data size remains the same ? I would think so, assuming I understand trim.

STARGAyesterday at 10:21 PM

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