One casual comment towards the end of recording Linux Out Loud Bill dropped a bomb on Wendy and me: ‘Data has weight.’ Matt was, unfortunately, absent that day and was spared this idea, but my brain? Already halfway down the rabbit hole. I dove into electrons, floating gates, E=mc², and (nearly) every heated Reddit thread on whether your full SSD secretly gains a few femtograms.
Bottom Line Up Front: The science says yes… kind of, but like any good tech enthusiast, I had to question it all. This is a bit of a nutty blathering and should not be taken seriously. It is meant as a fun musing about the idea that data has mass. I am not a scientist that performed the necessary experiments to prove or disprove any of the following claims. I do not have the equipment (if they even exist) to test and verify this theory either. So, assuming the source material is correct and electrons indeed have mass, SSDs do get heavier with more data.
Storage Technology
Solid-state drives (SSDs) are a type of non-volatile storage that rely on NAND flash memory to store data without moving parts. At the core of an SSD are billions of memory cells arranged in a grid-like structure, with each cell capable of holding one or more bits of information depending on the NAND type (SLC for 1 bit per cell, TLC for 3 bits per cell, which is common in consumer SSDs).
Hard disk drives (HDDs) use spinning platters and magnetic heads to store data. Data is stored by flipping the magnetic polarity on the platters as they spin around at 5400 RPM or more which merely rearranges existing atoms.
How NAND Flash Cells Hold Information
Each NAND flash cell is essentially a modified transistor, specifically a MOSFET (metal-oxide-semiconductor field-effect transistor) with an additional “floating gate” or, in modern 3D NAND, a charge trap layer. This isolated structure is sandwiched between insulating layers of oxide, allowing it to trap and retain electrical charge (electrons) even when power is off.
For more detail on this check out this site: https://www.extremetech.com/computing/how-do-ssds-work
Storing Data: To write data, a high voltage (around 15-20V) is applied to the control gate above the floating gate. This causes electrons from the transistor’s channel (the substrate) to “tunnel” through the thin oxide barrier via a quantum mechanical process called Fowler-Nordheim tunneling. The electrons get trapped in the floating gate, creating a negative charge. The presence and amount of this charge shift the cell’s threshold voltage—the voltage needed to turn the transistor on during a read operation.
In a single-level cell (SLC), there are two states: minimal/no trapped electrons, typically representing a ‘1’, erased state vs. a specific number of trapped electrons, representing a ‘0’, programmed state.
In multi-level cells like TLC (triple-level cell), the cell can hold 3 bits by using 8 distinct charge levels (0 to 7), each corresponding to a different number of trapped electrons (000, 001, up to 111). The exact number of electrons per level varies by technology, but in modern NAND, the difference between levels might be as little as 10-100 electrons due to miniaturization.
Older nodes used thousands, but current 3D NAND is far more efficient.
Reading Data: A lower read voltage is applied to the control gate, and the system measures how easily current flows through the transistor (source to drain). If the threshold voltage is low (few electrons), it reads as one value; if it reads high (more electrons), another. For multi-level cells, multiple reference voltages are checked to pinpoint the exact charge level.
Erasing Data: To reset a cell, a high voltage of opposite polarity tunnels the electrons back out of the floating gate, returning it to the erased state (usually all ‘1’s). Erases happen in large blocks (4-16 MB) because cells are wired in series strings.
Retention: The insulating oxide layers prevent the electrons from leaking out quickly, allowing data to persist for 10+ years under normal conditions. Over time, wear from repeated program/erase cycles (limited to ~1,000-100,000 per cell depending on type) can degrade this insulation, which is why SSDs use wear-leveling algorithms in their controllers to distribute writes evenly.
Addressing the Weight Question
HDDs, or more amusingly called, “spinning rust”, store data by flipping the magnetic polarity of tiny domains on the platter to north/south poles which represent 0/1. This rearranges existing atoms without adding or removing mass, it is just a change in orientation. There’s a minuscule energy difference that equates to a mass change via E=mc², but it’s on the order of 10^-18 grams for a full drive, utterly negligible.
https://physics.stackexchange.com/questions/31326/is-a-hard-drive-heavier-when-it-is-full
For SSDs, it’s different because data storage involves actual electrons being added to (or removed from) the cells during programming/erasing. Electrons do have mass: about 9.11 × 10^-31 kg each. When you write data, you’re typically programming more ‘0’s (adding electrons) from the erased state, all ‘1’s, which is fewer electrons. The electrons are supplied via the power connection, so yes, the drive technically gains mass as you fill it with data.
https://datarecovery.com/rd/does-a-full-hard-drive-weight-the-same-as-an-empty-hard-drive
The next obvious question is, by how much? We can crunch the numbers for a common, hypothetical, 1TB TLC SSD:
- 1TB = (about) 8 trillion bits.
- 3 bits per cell → ~2.67 trillion cells.
- Modern NAND might use ~100-400 electrons per level difference with 7 level differences. These exact charge levels are not public, this is best guess. For a conservative max-charge estimate per cell (full ‘000’ state in TLC), let’s use ~1,000 electrons.
- Max total electrons added: ~2.67 × 10^12 cells × 1,000 = ~2.67 × 10^15 electrons.
- Total added mass: ~2.43 × 10^-15 kg, or about 2.43 picograms (2.43 × 10^-12 grams), or 2,430 femtograms.
This is the theoretical maximum if every cell is fully programmed, real data, however is a mix. Average added mass is less (half that for random data). It’s so small that no scale on Earth could detect it, and factors like dust, temperature expansion, or even the drive’s plastic casing flexing would dwarf it. Some sources flip the convention (claiming drives get lighter), but that’s based on outdated or incorrect assumptions about ‘0’ vs. ‘1’ states. The net effect is a tiny increase when adding typical data.
Final Thoughts
In short, Bill wasn’t (theoretically) wrong, data does have weight but only on SSDs and they do get ever-so-slightly heavier when you write data, unlike HDDs. The difference, however, is practically zero. This is more of a fun physics trivia than anything measurable. If you’re visualizing electrons piling up like tiny weights, that’s accurate on a quantum scale!
So yeah, your SSD gets a femtogram heavier when you dump a bunch of Linux ISOs on it. But wait! Plug in your laptop, fire it up, and watch the magic: thanks to E=mc², the whole rig is technically heavier when powered on than when it’s dark and dreaming in sleep mode. Capacitors charged, RAM churning, fans spinning (if your machine has them), all that stored energy adds mass equivalent to… a few stray atoms’ worth of cosmic irony. Your computer isn’t just computing; it’s reluctantly participating in relativity. Congrats, you’ve gained the weight of pure theoretical physics. Now go fill it with more data and pretend the scale noticed.
References
https://www.extremetech.com/computing/how-do-ssds-work
https://electronics.stackexchange.com/questions/505361/how-many-excess-electrons-are-in-a-modern-slc-flash-memory-cell
https://physics.stackexchange.com/questions/31326/is-a-hard-drive-heavier-when-it-is-full
https://datarecovery.com/rd/does-a-full-hard-drive-weight-the-same-as-an-empty-hard-drive
https://www.sciencefocus.com/future-technology/does-a-usb-drive-get-heavier-as-you-store-more-files-on-it
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