[HN Gopher] Data Has Weight but Only on SSDs
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Data Has Weight but Only on SSDs
Author : LorenDB
Score : 53 points
Date : 2026-03-04 18:46 UTC (4 hours ago)
(HTM) web link (cubiclenate.com)
(TXT) w3m dump (cubiclenate.com)
| tliltocatl wrote:
| 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>2.43x10^-15</s> [my bad 1] 2.67x10^15 electrons is about 300uC
| - 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.
| zahlman wrote:
| TFA started out seeming well enough written but definitely
| turned LLM-padded in the middle. And yeah, I think you're right
| about the actual science.
| stackghost wrote:
| >2.43x10^-15 electrons
|
| I believe TFA reads 2.43x10^-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.
| jmalicki wrote:
| Neutrinos weight far less than electrons (but while NAND
| flash involves super weird physics it's not that weird)
| stackghost wrote:
| They do weigh far less, but a quantity of "10^-15
| electrons" is still impossible.
| alanh wrote:
| 10^-15 is not a negative number, just a small one.
| https://www.wolframalpha.com/input?i=10%5E-15+
| 1718627440 wrote:
| And it is less than one?
| JadeNB wrote:
| I think my favorite part of that comment is "documenting"
| that 10^(-15) is not negative by appealing to Wolfram
| Alpha.
| karmakaze wrote:
| Well you could have a virtual particle whose mass could be
| time-averaged.
| nickcw wrote:
| > 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!"
|
| From:
| https://tycho.parkland.edu/cc/parkland/phy142/summer/lecture...
| jmclnx wrote:
| 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 wrote:
| Was expecting Boltzmann and entropy to be involved at some point
| :(
| MengerSponge wrote:
| Yeah, I was motivated to go Wiki diving, where I just learned
| about the Shannon (unit).
| https://en.wikipedia.org/wiki/Shannon_(unit)
|
| Time to replace "I'm zero surprised" with "That's a zero
| Shannon event"
| nwellnhof wrote:
| 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.
| omgbear wrote:
| I think my network card does that.
| jerf wrote:
| 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/
| foobiekr wrote:
| this principle applies to a lot of things. signaling for
| example. optical links. oldschool optical links (OC48
| timeframe) did not feature scramblers and so a malicious
| packet could on occasion cause them to de-train and go out of
| sync since it's extended loss of light.
|
| long since fixed but a common problem.
| themafia wrote:
| More appropriately data has a temperature.
|
| https://en.wikipedia.org/wiki/Thermodynamic_beta
| antimatter15 wrote:
| 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 wrote:
| 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 wrote:
| Light bulbs in video games use real electricity.
| alanh wrote:
| "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'!
| erg0s4m wrote:
| So it has negative weight in this case.
| TazeTSchnitzel wrote:
| Lights in video games are real, but only if you're using an OLED
| or CRT.
| mrlonglong wrote:
| You need one of these !
|
| https://www.eejournal.com/fresh_bytes/how-do-you-weigh-a-pro...
| STARGA wrote:
| 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.
| bilsbie wrote:
| 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 wrote:
| I guess it's because the 1s weigh more than 0s? Which is
| counterintuitive because the 0s are chubbier.
| slicktux wrote:
| 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 wrote:
| Data has negative weight on punched cards or tape.
| 1970-01-01 wrote:
| Now do fiber and tell me the relativistic mass of my router so my
| ISP can charge me an overweight fee.
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