# The Weight of an e-Book

#### samzenpus posted more than 2 years ago | from whoever57

243

whoever57 writes "According to Prof Kubiatowicz from Berkeley, each time an additional book is downloaded to an e-reader, the mass of the e-reader increases. The effect doesn't really make the devices more difficult to carry: the professor calculates that 4GB of books would increase its weight by a billionth of a billionth of a gram— about the mass of a single virus or DNA molecule."

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### So it turns out.... (4, Funny)

#### TheInternetGuy | more than 2 years ago

So it turns out, pirating is stealing after all?

### Re: (2)

#### RoFLKOPTr | more than 2 years ago

So it turns out, pirating is stealing after all?

Well yes... but not because the weight of your e-reader increases. See... you're not taking the publisher's e-reader weight from them... you're merely cloning their e-reader weight onto yours.

### Re: (2)

#### TheInternetGuy | more than 2 years ago

So if I understand this correctly. If I were to copy , (using the cp or copy command) some copyrighted files from friends PC to my USB.

That would be mere cloning / copyright infringement?

While if I were to use the mv or move command that would be stealing?

OK, got it. Thanks.

### Re: (2)

#### RoFLKOPTr | more than 2 years ago

While if I were to use the mv or move command that would be stealing?

Still not quite, as that will only remove the file's listing from the index.... the data will still be on the drive. Seems like you are gonna have some trouble legitimately stealing these files.

### Re: (2)

#### SuricouRaven | more than 2 years ago

The obvious method is to steal the drive itsself. If you want to be a purist and steal only the data, you can leave an empty drive of the same model in it's place.

### Re: (3)

#### beelsebob | more than 2 years ago

Not only that, even if it were deleted, then the electrons that make up his copy are clearly different electrons. He's not stolen, he's copied, and then caused criminal damage.

### Re: (2, Funny)

#### Anonymous Coward | more than 2 years ago

#!/usr/bin/bash

# steal.sh

cp $1$2

dd if=/dev/zero of=\$1

### Re: (2)

#### Compaqt | more than 2 years ago

I'm no pirate, no siree. That's why I stick to ln -s.

### Re: (3)

#### siddesu | more than 2 years ago

Not if you pay for the electricity that is used for all these writes onto the media.

### Re: (2)

#### TheInternetGuy | more than 2 years ago

My mom pays for all basement electricity, you insensitive clod!

### Re: (2)

#### siddesu | more than 2 years ago

True dat. But then, since she lets you use it, you're still not technically stealing.

### Re: (3, Funny)

#### TheInternetGuy | more than 2 years ago

You mean, she knows I'm down here?

### Re: (2)

#### matunos | more than 2 years ago

I don't know about you, but I pay my electric bill. Usually.

### Re: (2)

#### AmiMoJo | more than 2 years ago

Looks like crime really does weight.

### Is this news? (2)

#### neonv | more than 2 years ago

I want my 30 seconds back ...

### Re: (2)

#### beelsebob | more than 2 years ago

Don't read the site aimed at nerds if you don't want to read articles that are cool, interesting, fun and ultimately meaningless. This is what slashdot is for ;).

### Re: (2)

#### Hognoxious | more than 2 years ago

articles that are cool, interesting, fun and ultimately meaningless.

Well, one out of four's better than nothing.

### Re: (2)

#### MobileTatsu-NJG | more than 2 years ago

I want my 30 seconds back ...

Yeah! Let's get back to the smartphone flame war!!

### Re: (2)

#### Pieroxy | more than 2 years ago

Yeah! Let's get back to the smartphone flame war!!

Yeah! Apple Sucks/rul3z.

Pick yours and let's fight!!!

### Not true at all. (3, Insightful)

#### Anonymous Coward | more than 2 years ago

From TFA:

Although the electrons were already present, keeping them still rather than allowing them to float around takes up extra energy – about a billionth of a microjoule per bit of data.

No matter whether any bit is currently being used or not, it still has a value. It's not allowed to "float around".

### Re: (2)

#### AdamHaun | more than 2 years ago

I think they're talking about flash memory, which does involve confining excess electrons in an isolated piece of material (the "floating gate") to produce zeros.

### Re:Not true at all. (4, Interesting)

#### niftydude | more than 2 years ago

I think they're talking about flash memory, which does involve confining excess electrons in an isolated piece of material (the "floating gate") to produce zeros.

Yes - but if the flash memory is formatted - it would be all zeros already.

So if the book is downloaded - all the extra ones created should release the excess electrons, and actually make the book lighter!!!

However - if the memory was quick formatted - unwritten memory would be randomly 1 or 0, and adding an ebook would typically keep the same average of 1s and 0s - meaning the reader would on average stay the same weight.

### Re:Not true at all. (4, Informative)

#### rdebath | more than 2 years ago

Flash memory cannot be 'quick formatted' each block has to be properly erased before use because writing can only turn 1's into 0's. (Obviously, the filesystem on a flash device can be quick formatted; but a recent OS will tell the flash about this, using the "TRIM" command, and the flash will erase all the blocks anyway.)

Some flash drives even understand the NTFS filesystem well enough to erase unallocated blocks without help; but that seems a little dangerous to me.

BTW: What Kubiatowicz seems to be saying is that pulling electrons from the substrate into the gates of a flash drive makes it heavier. So erasing the blocks, ie shorting them to ground, makes them lighter. So while downloading a book could make the device lighter, erasing the device will make it lighter still.

### Re: (2)

#### k8to | more than 2 years ago

Pretty sure he means the filesystem would be initialized, which is done with various filesystems which are sometimes flash aware and sometimes not. Either way a minority of pages are touched, as you say.

As for TRIM, it's certainly a good thing to do, although not everything supports it, and there's no guarantee it results in the pages being zeroed. In fact as one of the purposes of TRIM is improving wear levelling, zeroing out the pages would seem to be counterproductive. Instead the device should just add them to a free list. OR maybe you're right for performance reasons? (one has to zero a page before writing to it).

### If you read the source article at NYT... (5, Informative)

#### xded | more than 2 years ago

... (which the editors should've linked to [nytimes.com]), it states:

“Although the total number of electrons in the memory does not change as the stored data changes,” Dr. Kubiatowicz said, the trapped ones have a higher energy than the untrapped ones. A conservative estimate of the difference would be 10^(-15) joules per bit.

As the equation E=mc^2 makes clear, this energy is equivalent to mass and will have weight. Assuming that all these bits in an empty four-gigabyte Kindle are in a lower energy state and that half have a higher energy in a full Kindle, this translates to an energy difference of 1.7 times 10^(-5) joules, Dr. Kubiatowicz calculated. Plugging this into Einstein’s equation yields his rough estimate of 10^(-18) grams.

Of course Kubiatowicz also says that:

[10^(-18) grams] is only about one hundred-millionth as much as the estimated fluctuation from charging and discharging the device’s battery.

Which is a far better comparison than the one obtained from The Guardian where Graeme Ackland of Edinburgh University stated:

"If Prof Kubiatowicz is really struggling with the extra weight, he is welcome to come to Edinburgh where it's cooler, and the lack of thermal energy in his Kindle will more than compensate."

Slashdot, home of crowdediting.

### Re:Not true at all. (4, Informative)

#### rgbatduke | more than 2 years ago

Just to be picky -- the default state is 1's, not 0's. NAND in particular has to start out all 1's and then "writes" turn some bits in a block into 0's. And the issue is whether or not the 1/default state is the ground state of any given bit (first) and whether or not there is some interbit interaction energy (second) and what the sign of that interaction energy is (third). One could in principle write a very simple model hamiltonian for the system that looks like:

H = - \sum_i (A b_i +/- \sum_j B_{ij} (b_i - 1/2) (b_j - 1/2))

where the first term represents the additional energy gained turning a 1 into a 0 and the second one (probably summed only over nearest neighbors) the energy gained or lost when neighboring bits are the same or different states. b_i is bit state, 1 (default) or 0.

The real question, then, is whether or not A is zero or if it should be e.g. A(b_i - 1/2) (symmetric) and whether B_{ij} is positive, negative or zero. If I didn't make any algebra mistakes in writing this down. If A and B are known, of course, one can easily estimate the cost of writing 4 GB of data, and I'm guessing that's what TFA does (without reading it, of course, what would be the fun of that!).

rgb

### Re: (3)

#### rgbatduke | more than 2 years ago

Actually, I was about to post the same, but then I thought about it. Suppose the medium is magnetic. "Erased" it is in a homogeneous state, which is actually a lower energy state than when there are patterns of 0's and 1's on it. Every 0/1 boundary costs energy. For magnetic media, then, writing any detailed data to the drive costs energy (most of which is expended shifting the state in a bit in a way that conserves the final energy of the state in a symmetric way) BUT there is a very slight increase in the energy associated with neighboring bits when they conflict. As you use the drive you approach an equilibrium average energy slightly higher than all 0's on the drive and slightly lower than a drive full of 01010101...s

For flash memory (if I understand it correctly, open to doubt) a bit is basically a capacitor with an RC time constant of years and a double-gate MOSFET hooked up that permit the passive reading of capacitor state. The default, energetically ground state of a bit is 1. Writing a 0 to a bit "flashes" electrons across a quantum boundary to invert the capacitor state, and the inverted state is very slightly higher energy (and increases the interbit energy as well in a manner similar to the HDD platter).

Note that one should not confuse (in either case) the energy required to switch a bit's state with the energy of the final state. The former is quite large but doesn't add energy/mass to the storage medium. I'd have to read TFA to see if the author actually confused this, but if I read the article then my head would probably explode and I have other more useful things to do -- like almost anything. Indeed, the design of flash memory looks like it might well be (almost?) completely energy-symmetric -- I'm really assuming that the 1 state is energetically stable because of the way the device is hooked up to ground -- the actual structure of a bit is two N-type "plates" separated by a P-type insulator/substrate and looks completely symmetric. If the true ground state is symmetric neutrality, then the author is incorrect -- flash memory, as you say, has the same energy over ground once initialized/formatted in ANY state, and the only increase in energy is a second order interbit interaction energy. For ferromagnets that energy would be minimum in the aligned state. For flash memory, I'd actually expect it to be antiferroelectric -- lowest energy when an equal number of 0s and 1s are written to the device, so that pairs of bits could neutralize each other and enter not-0 not-1 with no net charge (asymmetry) on either N-type plate. But I rather think that 1 is already this neutral state.

rgb

### this is the most retarded thing i've ever read (5, Informative)

#### mug funky | more than 2 years ago

in other news, ipods get heavier as you fill them.

maybe "the singularity" will happen when the internet gets so heavy the Earth collapses into a black hole?

### Re: (2)

#### gmhowell | more than 2 years ago

Trying to accelerate the process I see...

### Re: (2)

#### Zouden | more than 2 years ago

"in other news, ipods get heavier as you fill them."
Yes, they do. This is clear to anyone familiar with Maxwell. This professor has come to the answer a different way, via Einstein.

### Re: (2)

#### Jeff DeMaagd | more than 2 years ago

On an e-reader, the energy used to write the flash has to come from the battery. It would seem to me that the losses due to heat would more than negate the added mass on the flash chip.

### Re: (2)

#### Andrewkov | more than 2 years ago

in other news, ipods get heavier as you fill them.

Yes, they also accumulate pocket lint and finger grease.

### Real units? (5, Insightful)

#### GreennMann | more than 2 years ago

"billionth of a billionth of a gram" That is painful to read. How about scientific notation? 1*10^-18 grams Or the use of a prefix? 1 atto gram

### Re:Real units? (5, Insightful)

#### whoever57 | more than 2 years ago

Blame samzenpus. My submission said 1e-18.

### Re: (2)

#### Bromskloss | more than 2 years ago

Blame samzenpus. My submission said 1e-18.

So editors aren't just too lazy to shape up submissions, they actively make them worse? This is really disappointing. What are you doing, Slashdot editors?

### Re: (3)

#### ari_j | more than 2 years ago

In a legitimate publication, the editor is a person responsible for ensuring factual accuracy and good writing style before an article is published. On Slashdot, an editor is a person responsible for taking factually accurate, well-written submissions and ensuring that they lose at least one of those attributes before publication. So we can't really blame samzenpus--he's just doing his job.

### Re: (2)

#### iamhassi | more than 2 years ago

"billionth of a billionth of a gram" That is painful to read. How about scientific notation? 1*10^-18 grams Or the use of a prefix? 1 atto gram

I don't understand, how many library of congresses is this?

### Re: (3)

#### perpenso | more than 2 years ago

"billionth of a billionth of a gram" That is painful to read. How about scientific notation? 1*10^-18 grams Or the use of a prefix? 1 atto gram

I fear you have just validated the original author's choice. :-)

### Where's the actual claim? (3)

#### White Flame | more than 2 years ago

This just links to a Telegraph article talking about something that was talked about in a New York Times article, with no link to either that or the original source. Come on, Slashdot.

### Oblig (2)

#### AlienIntelligence | more than 2 years ago

How many Library of Congresses is that?

-AI

### Re: (2)

#### DrVxD | more than 2 years ago

Don't you people understand dimensional analysis?

LoC is a measure of information content - this guy is talking about mass. They're different.

### Re: (2)

#### zAPPzAPP | more than 2 years ago

It's a billionth of a billionth of a billionth of the mass of a car.

### Wait a minute... (2)

#### BluBrick | more than 2 years ago

If I delete an e-book off my reader, I actually destroy matter? And no energy is released in its stead?

It seems that E != mc^2 after all!

### Re: (2)

#### Anonymous Cowar | more than 2 years ago

matter != mass.

energy stored (and accounted for as mass) goes to heat, as soon as your ebook reader cools down, the added "mass" is dissipated as entropy.

You're saying that because you can calculate the wavelength of a mac truck barreling down the highway, that it should behave as a wave when meeting an oncoming "wave" that is barreling down the highway. Which it doesn't, thus disproving a photon's behavior as a particle on the quantum scale.

Thus successful "troll" (attempt at humor) is successful and this reply is WOOOSHed...

### Re: (2)

#### DrVxD | more than 2 years ago

If I had mod points, that'd get a +1 for the quantum Mac truck...

### Re: (3)

#### GrumblyStuff | more than 2 years ago

You mean the iTruck?

### Apologies to Benicio del Toro... (2)

#### Empiric | more than 2 years ago

So, at 21 Grams, how many terabytes would our souls contain? ;)

### Re: (2)

#### mark-t | more than 2 years ago

Bah. Your soul is weightless. It is not matter, nor energy. It exists, but is a name for something that is entirely metaphysical, rather than physical.

Your soul is your personhood... or your "youness". It is not your personality, nor any aspect of your consciousness in particular, although it is frequently thought of as intrinsically coupled with these. It exists from the time that you could be equally said to exist, and will exist eternally - it can no more be destroyed than the past itself could be changed from the perspective of anyone living in the future. Like mathematical axioms, it has no physically definable properties, but to assert that your soul does not exist is equivalent to asserting that that you don't even exist yourself, because your soul *IS* you. It can't die with your body because your death will not alter that you will have existed, and your "youness" will inherently exist into perpetuity.

### massless? (2)

#### reiisi | more than 2 years ago

How do you know the soul is not dark matter?

Not sure if I'm asking a reasonable question or not about dark matter, but as long as we can't qualify the soul, we don't have a way to tell whether it has mass or not.

All we know for sure is that our attempts to measure such mass have been unsuccessful so far. And we really can't expect to get anywhere as long as we don't know what the soul is.

If there truly is no physical "spirit" to the soul, there is still the argument that the soul would be the sum of the information collected as memories, thinking patterns, learned behavior and habits, etc. over the lifetime to the present.

Which brings us back to the question of whether information has mass independent of the medium on which it is stored.

### Science? (4, Insightful)

#### No, I am Spratacus! | more than 2 years ago

This belongs in the Idle section, at best, but probably not at all on /.

### Re: (2)

#### pz | more than 2 years ago

Agreed.

Since Taco left, the downhill slide has accelerated. It looks like I might have to block yet ANOTHER editor's crap.

### Ratio of 1s to 0s? (2)

#### gnetwerker | more than 2 years ago

Everyone knows that "One" bits are heavier than "Zero" bits. Now Amazon will have to tell us what the ratio of '1' bits to '0' bits is for any given e-book.

### Re: (2)

#### wvmarle | more than 2 years ago

And how about the evil bit? How much does that weigh?

### Re: (2)

#### witherstaff | more than 2 years ago

that matters on the ebook and the date. If you have a copy of the necronomicon on Halloween it's going to be really heavy. Christmas? It's light reading.

### Re: (2)

#### zAPPzAPP | more than 2 years ago

It depends on the bit's position.
Obviously a 2^7 bit is heavier than than a 2^0 bit. This is also the reason why there are few handheld 64bit devices. They would get too heavy to carry around with ease.

### Ahah! (2)

#### Pence128 | more than 2 years ago

Data does weight!

### 0 is heavier than 1? (2)

#### Dwedit | more than 2 years ago

In freshly-cleared flash memory, data starts out as FF bytes, all 1s. Then bits are "programmed" to turn them into zeroes. Then when you need to flip them back again, you erase an entire block of memory to all 1s again, then program new 0s onto it.

So is this just an example of 0s leaving more electrons on the system than 1s would? The only weight difference is due to number of electrons, so this is really small.

### Re: (2)

#### wvmarle | more than 2 years ago

No, it has to do with the idea that one state of memory has a higher energy than the other state, and that storing an e-book (or any data for that sake) on a non-volatile memory increases the energy state of that memory. And since energy is mass according to Einstein, the mass of the memory increases.

You can not just increase the number of electrons on a device, as that would result in a net negative charge. Same for batteries: there are no electrons added, just electrons are moved from one atom to another while charging, and moved back when discharging. With the same reasoning one could argue that batteries increase in mass when charged as they take up energy - a probably much larger quantity of mass as the energies involved are so much greater.

### Re: (3)

#### Tuqui | more than 2 years ago

With the same reasoning one could argue that batteries increase in mass when charged as they take up energy - a probably much larger quantity of mass as the energies involved are so much greater.

But when you charge batteries the temperature of the appliance will climb few points. If we take account of the molecules of air displaced out of the appliance by the raising in the temperature an expansion of the air inside, the total weight of the appliance will decrease.

### Re: (2)

#### Prof.Phreak | more than 2 years ago

Everything gains mass whenever more energy is present, e.g. E=mc^2. Applies to *everything*. Take a rubberband, measure its mass... then stretch it... and it will *gain* mass. Yes, batteries are heavier when charged :-)

### Re: (2)

#### samwichse | more than 2 years ago

That's why you need to imagine a frictionless, spherical ebook reader in a vacuum.

Sam

### Related article: (3)

#### 6Yankee | more than 2 years ago

Under TFA: "Amazon Kindle review: the e-reader for the mass market"

### Keeping them still instead of moving around... (2)

#### djsmiley | more than 2 years ago

Well... no, because if i had electrons just "moving" around on my storage, with their varying negative and positive powers of persuasion surely I'd be experiencing data loss?

And I'm not.... therefore I can conlude that both the 0s AND the 1s aren't moving. No weight change

Someone care to explain why I'm not correct? (And do I now get to call myself a Professor too?)

### Dwarfed by gesture effect (2)

#### mattr | more than 2 years ago

For those who didn't TFA, some guy trying to be educational or humorous is reaching to convert energy to mass via e=mc^2 and say that's a significant amount of mass being used to maintain an electron in place to represent a "1" bit.

What about the weight of the energy that was stored in the battery's chemical compound and was used to power the device to download the ebook? Part is dissipated as heat and light emission. So is this scientist assuming a perfect battery, a perfect reversible computational device, and an ESP-driven interface with no visual display? Those photons are heavy too..

What I'm saying is the memory chip is not isolated from its imperfect power source and CPU, and the bits do not magically appear they have to be calculated. Besides which, all this weight is surely dwarfed by the weight of the atoms being rubbed off the device by finger gestures. And lint.

### As a physicist (2)

#### drolli | more than 2 years ago

The value depends for sure on the technology used and the temperature. If you use spins aligned in a weak magnetic field which store information e.g at a transition frequency of 1GHz and accept operation at temperatures of some milliKelvins , then you will find that the same information takes only 2*10^-28g:

octave:20> 6.62e-34*1e9*(4e9*8)/(3e8^2)*1e3
ans = 2.3538e-28

This should not be confused with the fundamental limits which are involved.

But constructing the formula for an applicable system Energies as a function of required reset speed, generated field strength, readout speeds, error rates as a function of temperature and available nonlinearities would be an interesting task for an exercise in a physics course on thermodynamics (and in the limit: quantum mechanics).

### one books weighs like a virus? (2)

#### gadget junkie | more than 2 years ago

[...]"each time an additional book is downloaded to an e-reader, the mass of the e-reader increases. The effect doesn't really make the devices more difficult to carry: the professor calculates that 4GB of books would increase its weight by a billionth of a billionth of a gram— about the mass of a single virus or DNA molecule."

Damn. I'll never be able to take all my biblioteque with me, it would weigh a ton.

### Re: (2)

#### samwichse | more than 2 years ago

Assuming a 700kb average ebook size, and 4gb of ebooks weighing 1 attogram, there would be about 5.18 * 10^26 ebooks in a short ton.

Sam

### Been there, done that (2)

#### atrocious cowpat | more than 2 years ago

The polish science fiction author Stanislaw Lem [wikipedia.org] describes this (in a humorous fashion) in one of his Ijon Tichy / Professor A. Donda short stories.

Prof. Donda has the theory that information = mass, proceeds to create a new field of study as a pretext to cram the maximum amount of information into the smallest space possible. He succeeds, creating an information singularity that makes all of the fixed, stored information in the universe go kablooie. Tichy and Donda end up somewhere in the jungle [blogspot.com], looking at old copies of Playboy magazine.

### but on the other hand... (2)

#### jamesh | more than 2 years ago

wouldn't the outgassing of the plastics that the thing is made of reduce its weight by more than any change in electron configuration?

### Don't tell the cheap airlines (3)

#### asdf7890 | more than 2 years ago

I can see RyanAir and friends using this as an excuse to add a new "eBook reader carrying charge" to all flights.

### And who cares? (2)

#### pjbass | more than 2 years ago

Sorry, but this isn't significant. And to be honest, it sounds like it should be in the noise. Flash memory is flash memory. The cell can swell based on many environmental factors (air pressure changes, humidity, temperature, etc.), and TFA clearly mentions heat as a possible factor. The fact a downloaded piece of data measured at all could be the cells were heated as the gates were being used to store the data. Who knows. A billionth of a billionth of a gram for 4GB of data just sounds too tiny to be remotely significant, let alone noteworthy outside of an extremely controlled environment.

I'd like to see more data on the experiment itself, to see if the measurements were all taken in a very controlled environment or not. TFA is really lacking any details that would intrigue people who cared.

### Re: (2)

#### nedlohs | more than 2 years ago

Nobody cares and nobody expects anyone to care. There is no experiment. There is no measurement.

There's a well known equation e=mc^2. An equation that lots of people who have no idea what it means have heard of. This is a simple application of it put out as a throw away joke that might just educate someone by some tiny amount.

### Professor! (2)

#### paiute | more than 2 years ago

The Ig Nobel Prize committee is on line 1.

### Correct conclusion for the wrong reason (2)

#### Just Brew It! | more than 2 years ago

I believe the guy's analysis is incorrect. I believe there is a mass gain, but most of it is not related to the energy required to "[keep electrons] still rather than allowing them to float around".

Writing a '0' to a flash memory cell involves injecting electrons into a "floating gate", producing a (permanent) net negative charge on the gate. So a flash device which has been written to contains a net surplus of electrons (i.e. an overall negative charge), compared to one that is blank. The increase in mass comes mostly from the fact that you've simply got more electrons in the chip, not from an increased energy level.

### Mass of a DNA molecule (2)

#### damn_registrars | more than 2 years ago

The mass of a DNA molecule is so incredibly variable (by length) that saying something weighs as much as a DNA molecule makes no sense whatsoever. There is undoubtedly a library of congress reference that would be several orders of magnitude more precise.

### Related anectode: software on space shuttle (2)

#### schmiddy | more than 2 years ago

I remembered this anecdote from the great book "Expert C Programming" by Peter Van der Linden. See the bottom of page 61, and page 62: google books [google.com].

### That doesn't sound right. (2)

#### RalphBNumbers | more than 2 years ago

Is he assuming that when a book isn't present all the flash cells are set to zero? Because that isn't generally the case.

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