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.
> So, assuming the source material is correct and electrons indeed have mass, SSDs do get heavier with more data.
That is definitely wrong! No way the source material has more electrons. The only way it could do that is by being charged.
Richard Feynman, The Feynman Lectures:
"If you were standing at arm's length from someone and each of you had one percent more electrons than protons, the repelling force would be incredible. How great? Enough to lift the Empire State Building? No! To lift Mount Everest? No! The repulsion would be enough to lift a "weight" equal to that of the entire earth!"
I believe TFA reads 2.43×10^-15 kg, not electrons. Unless SSDs are creating new and exciting physics, one can't have less than one electron, as it's an elementary particle.
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.
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.
Amusingly, that's unnecessary, but possibly not for the reason most people think. It's not because the hard drive hardware is oblivious to runs of 0s and 1s exactly... it's because it's actually so sensitive that it already is recording the data in an encoding that doesn't allow for long runs of 0s and 1s. You can store a big file full of zeros on your disk and the physical representation will be about 50/50 ones and zeros on the actual storage substrate already. Nothing you do at the "data" layer can even create large runs of 0s or 1s on the physical layer in the first place. See https://www.datarecoveryunion.com/data-encoding-schemes/
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.
"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.
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.
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.
That is definitely wrong! No way the source material has more electrons. The only way it could do that is by being charged.
Richard Feynman, The Feynman Lectures: "If you were standing at arm's length from someone and each of you had one percent more electrons than protons, the repelling force would be incredible. How great? Enough to lift the Empire State Building? No! To lift Mount Everest? No! The repulsion would be enough to lift a "weight" equal to that of the entire earth!"
From: https://tycho.parkland.edu/cc/parkland/phy142/summer/lecture...
I believe TFA reads 2.43×10^-15 kg, not electrons. Unless SSDs are creating new and exciting physics, one can't have less than one electron, as it's an elementary particle.
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.
Massless propulsion??
https://www.eejournal.com/fresh_bytes/how-do-you-weigh-a-pro...
Time to replace "I'm zero surprised" with "That's a zero Shannon event"
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.
https://en.wikipedia.org/wiki/Thermodynamic_beta
Also would trimming cause a different value even though the data size remains the same ? I would think so, assuming I understand trim.