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The Weight of an e-Book 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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The Weight of an e-Book

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  • by TheInternetGuy ( 2006682 ) on Monday October 31, 2011 @01:25AM (#37891814)
    So it turns out, pirating is stealing after all?
    • 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.

      • 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.

        • 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.

          • 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.
          • 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: (Score:2, Funny)

          by Anonymous Coward



          cp $1 $2

          dd if=/dev/zero of=$1

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

    • by siddesu ( 698447 )
      Not if you pay for the electricity that is used for all these writes onto the media.
    • I don't know about you, but I pay my electric bill. Usually.

    • by AmiMoJo ( 196126 )

      Looks like crime really does weight.

  • I want my 30 seconds back ...

    • 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 ;).

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

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

    • I want my 30 seconds back ...

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

      • by Pieroxy ( 222434 )

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

        Yeah! Apple Sucks/rul3z.

        Pick yours and let's fight!!!

  • Not true at all. (Score:3, Insightful)

    by Anonymous Coward on Monday October 31, 2011 @01:30AM (#37891858)

    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".

    • by AdamHaun ( 43173 )

      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. (Score:4, Interesting)

        by niftydude ( 1745144 ) on Monday October 31, 2011 @03:06AM (#37892292)

        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. (Score:4, Informative)

          by rdebath ( 884132 ) on Monday October 31, 2011 @03:40AM (#37892400)

          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.

          • by k8to ( 9046 )

            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 a

        • by xded ( 1046894 ) on Monday October 31, 2011 @05:29AM (#37892832)
          ... (which the editors should've linked to []), 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. (Score:4, Informative)

          by rgbatduke ( 1231380 ) <<rgb> <at> <>> on Monday October 31, 2011 @05:44AM (#37892898) Homepage
          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!).

    • 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
  • by mug funky ( 910186 ) on Monday October 31, 2011 @01:30AM (#37891860)

    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: (Score:3, Funny)

      Your ideas are intriguing to me and I wish to subscribe to your newsletter.
      • by gmhowell ( 26755 )

        Your ideas are intriguing to me and I wish to subscribe to your newsletter.

        Trying to accelerate the process I see...

    • by Zouden ( 232738 )

      "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.

      • 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.

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

      Yes, they also accumulate pocket lint and finger grease.

  • Real units? (Score:5, Insightful)

    by GreennMann ( 1525279 ) <> on Monday October 31, 2011 @01:38AM (#37891904)
    "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? (Score:5, Insightful)

      by whoever57 ( 658626 ) on Monday October 31, 2011 @01:55AM (#37891986) Journal
      Blame samzenpus. My submission said 1e-18.
      • 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?

      • by ari_j ( 90255 )
        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.
    • "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?

    • "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. :-)

  • by White Flame ( 1074973 ) on Monday October 31, 2011 @01:47AM (#37891946)

    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.

  • How many Library of Congresses is that?


    • by DrVxD ( 184537 )

      Don't you people understand dimensional analysis?

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

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

  • 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!
    • 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
  • So, at 21 Grams, how many terabytes would our souls contain? ;)
    • by mark-t ( 151149 )

      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

      • 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 inf

  • Science? (Score:4, Insightful)

    by No, I am Spratacus! ( 2281684 ) on Monday October 31, 2011 @02:01AM (#37892030)

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

    • by pz ( 113803 )


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

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

  • Data does weight!
  • 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.

    • 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

      • by Tuqui ( 96668 )

        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.

        • 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 :-)

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


  • by 6Yankee ( 597075 ) on Monday October 31, 2011 @02:59AM (#37892272)

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

  • 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?)

  • 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

  • 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

  • [...]"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.
    • 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.


  • The polish science fiction author Stanislaw Lem [] 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 [], looking a
  • wouldn't the outgassing of the plastics that the thing is made of reduce its weight by more than any change in electron configuration?

  • by asdf7890 ( 1518587 ) on Monday October 31, 2011 @05:53AM (#37892938)
    I can see RyanAir and friends using this as an excuse to add a new "eBook reader carrying charge" to all flights.
  • 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

    • 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.

  • The Ig Nobel Prize committee is on line 1.
  • 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

  • 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.
  • 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 [].
  • 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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