alt Hacker NewsData Has Weight but Only on SSDs
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The premise has a subtle error. NAND flash stores data by trapping electrons on floating gates, but those electrons come from the substrate — they are not created. The total electron count in the chip stays constant. What changes is the charge distribution across gates.
If anything, the energy stored in the electric fields of charged floating gates contributes a tiny amount of mass via E=mc², but this is orders of magnitude below the article's estimate and would apply to any capacitor, not just SSDs.
The more interesting physical question is whether the information itself has a thermodynamic weight. Landauer's principle says erasing one bit dissipates at least kT ln(2) of energy. By mass-energy equivalence, storing N bits in a maximally efficient reversible memory would have a mass contribution proportional to the information entropy. But this is around 10^-38 kg per bit — unmeasurable with any current technology.
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??
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.
You need one of these !
https://www.eejournal.com/fresh_bytes/how-do-you-weigh-a-pro...
Lights in video games are real, but only if you're using an OLED or CRT.
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.
Light bulbs in video games use real electricity.
Was expecting Boltzmann and entropy to be involved at some point :(
"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'!
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.
More appropriately data has a temperature.
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.
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.