# iPod weighing more when full **URL:** \ **Category:** Factual Questions\ **Created:** [August 7, 2008, 2:33pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167 "2008-08-07T14:33:40Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [August 9, 2008, 3:54pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/61 "2008-08-09T15:54:10Z")
[QUOTE=spingears] They are not one’s or zero’s as you concieve them. They are simply positions in the solid state that are either on or off which are equivalent in meaning to 1’s and 0’s. [/QUOTE] WARNING! WARNING! Statements in this thread tread a fine line between valid scientific observations and the science of the whoosh. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [August 9, 2008, 5:31pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/62 "2008-08-09T17:31:34Z")
Let’s start at the beginning. The premise is that there are extra electrons added to the flash chip when it is programmed. What is now positively charged? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 9, 2008, 5:46pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/63 "2008-08-09T17:46:50Z")
[QUOTE=gazpacho] Let’s start at the beginning. The premise is that there are extra electrons added to the flash chip when it is programmed. What is now positively charged? [/QUOTE] Think of it this way: Some energy is given to a few electrons, enough to move them through an insulator, and away from the bulk of the transistor. Those electrons leave holes in the transistor, however, there is not a one-to-one correspondence of electrons to holes, because the electrons have been moved some finite distance away from the bulk of the transistor. So, the bulk has a slight positive charge, which gets cancelled by electrons from the battery, and then either from the battery being charged, or from free electrons in the surrounding area (your hand). Agreed, that this effect is slight, but I think it’s non-zero. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [August 9, 2008, 6:05pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/64 "2008-08-09T18:05:49Z")
[QUOTE=beowulff] Think of it this way: Some energy is given to a few electrons, enough to move them through an insulator, and away from the bulk of the transistor. Those electrons leave holes in the transistor, however, there is not a one-to-one correspondence of electrons to holes, because the electrons have been moved some finite distance away from the bulk of the transistor. So, the bulk has a slight positive charge, which gets cancelled by electrons from the battery, and then either from the battery being charged, or from free electrons in the surrounding area (your hand). Agreed, that this effect is slight, but I think it’s non-zero. [/QUOTE] The slight positive charge of the bulk is canceled by electrons in the floating gate. There are no extra electrons in the flash. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [August 9, 2008, 6:14pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/65 "2008-08-09T18:14:25Z")
Lets imagine a flash chip a micro controller and a battery powering these things in the vacuum of deep space. At some point the micro controller starts writing to the flash. What in this system is becoming positively charged as the flash chip is becoming negatively charged? ---
**Author:** ![Darryl\_Lict](https://avatars.discourse-cdn.com/v4/letter/d/7cd45c/32.png) [@Darryl\_Lict](https://boards.straightdope.com/u/Darryl_Lict)\ **Post date:** [August 9, 2008, 6:14pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/66 "2008-08-09T18:14:59Z")
[QUOTE=Squink] If technology hasn’t outstripped my understanding of magnetic storage, a one and a zero are differentiated merely by the direction of a magnetic field on the disc. If the north pole is up, it’s a one, if down, it’s a zero, or vice versa. While a disk with random 1’s and zero’s wouldn’t weigh any more than a disk with all 1’s or all zero’s, it might be possible to detect whether the data on a disc is randomized, or uniformly 1’s or 0’s, by measuring the resistance of the iPod to rotation in the earth’s magnetic field. All 1’s or 0’s will produce a stronger net magnetic field than would random data. [/QUOTE] Technology has indeed outstripped your understanding. I’ve been out of the field for ages, but a long time ago IBM introduced PRML coding (Partial Response Maximum Likelihood, I believe). It has to do with the concept that you can stuff more bits closer together resulting in complex waveforms that are sampled with a high speed A/D converter and you can derive the information from an algorithm that uses past waveform sample information. From what I remember, you could pack increasingly larger amounts of data as the signal to noise ratio of the channel increases. OK, I’m hungover, so I may be full of shit. In any case, the effect of writing bits to a hard drive will not have an overall change in the magnetic signal, so I think in the case of a hard drive, there will not be a net change in weight of the hard drive. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 9, 2008, 6:42pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/67 "2008-08-09T18:42:34Z")
[QUOTE=gazpacho] Lets imagine a flash chip a micro controller and a battery powering these things in the vacuum of deep space. At some point the micro controller starts writing to the flash. What in this system is becoming positively charged as the flash chip is becoming negatively charged? [/QUOTE] Obviously, in an isolated system the total number of electrons doesn’t change. It’s only in a system that has access to free electrons (like in the real world), where the number increases after programming. ---
**Author:** ![Seeker\_of\_Truth\_and\_Beauty](https://avatars.discourse-cdn.com/v4/letter/s/f14d63/32.png) [@Seeker\_of\_Truth\_and\_Beauty](https://boards.straightdope.com/u/Seeker_of_Truth_and_Beauty)\ **Post date:** [August 9, 2008, 8:34pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/68 "2008-08-09T20:34:45Z")
Two pages and no mention of the jerks in iPod six? I’m somewhat disappointed. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [August 9, 2008, 8:50pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/69 "2008-08-09T20:50:39Z")
[QUOTE=beowulff] Obviously, in an isolated system the total number of electrons doesn’t change. It’s only in a system that has access to free electrons (like in the real world), where the number increases after programming. [/QUOTE] This is the real world we send things with flash into space and they work. Do the electronics work differently in space? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 9, 2008, 9:10pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/70 "2008-08-09T21:10:28Z")
[QUOTE=gazpacho] This is the real world we send things with flash into space and they work. Do the electronics work differently in space? [/QUOTE] There are plenty of free electrons in space, and besides, it doesn’t matter - who cares if the weight of a spacecraft is a few electrons heavier or lighter. You might have an easier time if you do some thought experiments about golf-leaf electroscopes, and what happens to the electrons in your body when you touch them… ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [August 9, 2008, 10:05pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/71 "2008-08-09T22:05:27Z")
[QUOTE=beowulff] There are plenty of free electrons in space, and besides, it doesn’t matter - who cares if the weight of a spacecraft is a few electrons heavier or lighter. You might have an easier time if you do some thought experiments about golf-leaf electroscopes, and what happens to the electrons in your body when you touch them… [/QUOTE] You might have an easier time if you can decide what is keeping the free electrons in the flash chip from migrating to the thing that is now positively charged since it gave up its electrons to the flash chip. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 9, 2008, 11:47pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/72 "2008-08-09T23:47:35Z")
[QUOTE=gazpacho] You might have an easier time if you can decide what is keeping the free electrons in the flash chip from migrating to the thing that is now positively charged since it gave up its electrons to the flash chip. [/QUOTE] Huh? They’re trapped by an insulator - that’s what makes a flash chip non-volatile. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [August 10, 2008, 12:57am UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/73 "2008-08-10T00:57:10Z")
[QUOTE=beowulff] Huh? They’re trapped by an insulator - that’s what makes a flash chip non-volatile. [/QUOTE] Not the electrons in the floating gate. The electrons in the bulk. The electrons in the ground wires on the chip and the electrons in the vdd wires on the chip. They will more from the more negative area near the trapped electrons in the floating gate to the more positive areas until there is no longer an electric field present in the conducting areas. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 10, 2008, 1:05am UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/74 "2008-08-10T01:05:01Z")
[QUOTE=gazpacho] Not the electrons in the floating gate. The electrons in the bulk. The electrons in the ground wires on the chip and the electrons in the vdd wires on the chip. They will more from the more negative area near the trapped electrons in the floating gate to the more positive areas until there is no longer an electric field present in the conducting areas. [/QUOTE] I completely agree. However, as I’ve mentioned earlier, I don’t think that if you move 10 electrons from the bulk to the floating gate, you generate 10 holes. Because the gate is physically distant, maybe you only get 8 holes, which leaves from for two electrons to take their place. These electrons will eventually be picked up from the outside of the iPod. ---
**Author:** ![Khampelf](https://avatars.discourse-cdn.com/v4/letter/k/8e7dd6/32.png) [@Khampelf](https://boards.straightdope.com/u/Khampelf)\ **Post date:** [August 10, 2008, 2:20pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/75 "2008-08-10T14:20:34Z")
[QUOTE=Musicat] WARNING! WARNING! Statements in this thread tread a fine line between valid scientific observations and the science of the whoosh. [/QUOTE] Well, someone did ask if internal electron wear could affect the weight, so there is an aspect of science friction to the discussion. And we’re ignoring the relative speed of the Ipod to the observer. As we approach c, every song starts sounding like the Ramones… Short and Heavy. ---
**Author:** ![RaftPeople](https://avatars.discourse-cdn.com/v4/letter/r/6f9a4e/32.png) [@RaftPeople](https://boards.straightdope.com/u/RaftPeople)\ **Post date:** [August 10, 2008, 4:35pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/76 "2008-08-10T16:35:30Z")
**beowulff** , fliping a bit in flash is just movement of electrons, no change in number. Charging a battery is just movement and using that charge is just movement. Where is the gain/loss of electrons? I just noticed the other posts, I’ll go back and read. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 10, 2008, 6:29pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/77 "2008-08-10T18:29:07Z")
[QUOTE=RaftPeople] **beowulff** , fliping a bit in flash is just movement of electrons, no change in number. Charging a battery is just movement and using that charge is just movement. Where is the gain/loss of electrons? I just noticed the other posts, I’ll go back and read. [/QUOTE] You don’t understand Flash memory, then. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [August 10, 2008, 7:34pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/78 "2008-08-10T19:34:39Z")
**Beowulff** , I’m trying to understand what you think is going on. Are you saying an IPOD with no data (all zeros) on it has no net charge, but after adding mp3s it will have a net negative charge? Or are you saying an IPOD with no data (all zeros) on it has no net charge, and after adding mp3s it has no charge, but then over time it will pick up electrons from the environment and gain a net negative charge? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 10, 2008, 7:49pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/79 "2008-08-10T19:49:37Z")
[QUOTE=ZenBeam] **Beowulff** , I’m trying to understand what you think is going on. Are you saying an IPOD with no data (all zeros) on it has no net charge, but after adding mp3s it will have a net negative charge? Or are you saying an IPOD with no data (all zeros) on it has no net charge, and after adding mp3s it has no charge, but then over time it will pick up electrons from the environment and gain a net negative charge? [/QUOTE] Actually, an iPod with no data is all ones. But, other than that, the latter. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [August 10, 2008, 9:38pm UTC](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167/80 "2008-08-10T21:38:11Z")
[QUOTE=beowulff] > [@ZenBeam](#): > > **Beowulff** , I’m trying to understand what you think is going on. Are you saying an IPOD with no data (all zeros) on it has no net charge, but after adding mp3s it will have a net negative charge? > Or are you saying an IPOD with no data (all zeros) on it has no net charge, and after adding mp3s it has no charge, but then over time it will pick up electrons from the environment and gain a net negative charge? Actually, an iPod with no data is all ones. But, other than that, the latter. [/QUOTE] Why would it do that? When the IPOD has no net charge, there’s no force attracting electrons, and once it started to gain a negative charge, electrons would be repelled. [Previous page](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167.md?page=3) [Next page](https://boards.straightdope.com/t/ipod-weighing-more-when-full/459167.md?page=5)