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Does data have weight?
- Thread starter Zwhaler
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Technically, there is a change in weight. Data is stored in flash in the form of trapped electrons. The device that it is plugged into when data was being written will either drain or store electrons at specific locations on the semiconductor when new data is written. So for example, a document that is basically represented by all 1's (or on-bits) will have charge stored on all the sites where as a document that is all 0's charge removed from all the sites. Electrons do have a weight. It's just so small that you can't measure them in any conventional way. So no, you can't feel any difference. However, there is technically a change in weight.
Case closed?
Nope, not at all.
Flash memory is indeed a change in the charge state of a given transistor, but all that takes place is the promotion of an electron from one region to the next. The entire device must remain charge-neutral, and thus no net gain in mass occurs.
As far as Stored Data goes, data stored on a hard disk is merely a collection of on/off switches (yes, I know it's an oversimplification, but it works for this purpose). Therefore, since the transmitted data arrives as a set of instructions that tells which switches are to be flipped (do me a favor, and think binary with me here) and is NOT stored as photons, but as switch positions, Stored Data has no actual physical weight, until it is transmitted and becomes photons again.
True enough, but the physicist in me has to point out that photons are massless, and so even if they were absorbed there would be no gain in mass.
True enough, but the physicist in me has to point out that photons are massless, and so even if they were absorbed there would be no gain in mass.
ignoring relativistic mass
True enough, but the physicist in me has to point out that photons are massless, and so even if they were absorbed there would be no gain in mass.
but...a photon has zero resting mass, but as it gains speed it picks up momentum. how can a photon be massless when it has the ability to possess momentum?
No. The bafflement in this thread baffles me. Hard drives are sealed. No matter goes into or out of them; data is simply a different arrangement of the material already there. Has no one ever attended a science class?
--Eric
Actually, they're not sealed. There's a tiny hole (that generally says not to block it) that lets in air so the heads can ride on a cushion of it. That's why things like Microdrives say not to operate them over a certain altitude- the air isn't dense enough to float the heads over the platter and you end up with a head crash.
When a hard drive dies it loses 21 grams. This suggests that data does indeed have mass.
Magnetic polarization is a compelling theory on data storage. I will have to research that up on Wikipedia.
I remember reading a whole article about the 21 grams thing, pretty interesting, although I think it's all BS.
Well, how far into quantum mechanics must we go?
After all, photons have nonzero energy and energy is equivalent to mass according to Einstein's famous relation. The problem here is that we are using two different definitions of the word 'mass'.
The old definition of mass, called "relativistic mass," assigns a mass to a particle proportional to its total energy E, and involved the speed of light, c, in the proportionality constant:
m = E / c^2. (1)
This definition gives every object a velocity-dependent mass.
The modern definition assigns every object just one mass, an invariant quantity that does not depend on velocity. This is given by
m = E0 / c^2, (2)
where E0 is the total energy of that object at rest.
The first definition is often used in popularizations, and in some elementary textbooks. It was once used by practicing physicists, but for the last few decades, the vast majority of physicists have instead used the second definition. Sometimes people will use the phrase "rest mass," or "invariant mass," but this is just for emphasis: mass is mass. The "relativistic mass" is never used at all.
Note, by the way, that using the standard definition of mass, the one given by eqn (2), the equation "E = m c^2" is not correct. Using the standard definition, the relation between the mass and energy of an object can be written as
E = m c^2 / sqrt(1 - v^2/c^2), (3)
or as
E^2 = m^2 c^4 + p^2 c^2, (4)
where v is the object's velocity, and p is its momentum.
In one sense, any definition is just a matter of convention. In practice, though, physicists now use this definition because it is much more convenient. The "relativistic mass" of an object is really just the same as its energy, and there isn't any reason to have another word for energy: "energy" is a perfectly good word. The mass of an object, though, is a fundamental and invariant property, and one for which we do need a word.
only one thing wrong with you explanation there. 1 and 0 are based on what the magnetic direction is on the bytes on the a hard drive so boils down to electron spin. the hard drives total charge is for all intense purposes neutral.
Storing data in a charged form like what you are saying is great and easy way to lose it. The reason they say do not put magnetics near hard drives (or in the old days floppies) is because you screw up the orientation of a bunch of the bites on there and which direction they are facing.
Sure. The thing is that it's a tad blurry, as it was a 1/30 sec exposure at 360mm... Looks good on a 800x600 but not-so-good at a larger size.