Data Has Weight but Only on SSDs

tliltocatl

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.

jmclnx

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.

epx

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

nwellnhof

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.

themafia

More appropriately data has a temperature. https://en.wikipedia.org/wiki/Thermodynamic_beta

antimatter15

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.

tlb

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.

stephbook

Light bulbs in video games use real electricity.

alanh

"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'!

TazeTSchnitzel

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

mrlonglong

You need one of these ! https://www.eejournal.com/fresh_bytes/how-do-you-weigh-a-pro...

bilsbie

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??

TurdF3rguson

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

slicktux

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!

dale_glass

Data has negative weight on punched cards or tape.

1970-01-01

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

SuperscalarMeme

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.

Nevermark

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.

SanjayMehta

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.

CalChris

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.