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Name: Chase
Status: Student
Grade: 9-12
Location: IN
Country: United States
Date: March 2009

Does an Ipod, MP3 player, or any other storage unit, gain weight when information (music, pictures, video) is added to the device?

Nope, no weight is added. The information is stored by rearranging the magnetic material, not by adding to it.

Hope this helps,
Burr Zimmerman

Hi Chase,

An Ipod, or any other electronic device does not gain weight as more data is stored. Similarly, your computer does not get heavier as you store more data in the hard drive, or RAM. This situation is no different than recording on a cassette tape, which also does not weigh more after you finish recording on it.

The question you need to ask someone who tells you that an Ipod DOES weigh more after storing data, is: where the heck could that extra mass come from? If the weight WERE to increase, that means that some extra mass had to come from somewhere, and flow into the Ipod... but from where? After all, the cable you connect to an Ipod as you are sending it an MP3 file, is solid wire, not a hollow tube that something could flow through and into the MP3's memory or hard drive! Since mass cannot materialize out of thin air, and since the MP3 player is fed its MP3 files via a solid wire connection (or even wirelessly), it is clear --even if one does not understand how a hard drive or flash memory works-- there is no way possible that the MP3 player (or other device) could gain weight as more data is stored.


Bob Wilson

None that anybody could confirm, Chase. All the same atoms are present in the box, but in slightly different configurations. So much for matter.

In theory, stored energy has mass too, according to special relativity, but... A lot of energy is used to switch states, but most of that gets turned into heat which exits the box. A little energy difference sometimes exists between the one state and the zero state of a stored bit (particularly for flash memory) but information tends to use equal numbers of ones and zeroes, whether it is music or silence. The entropy will vary according to information content: dense information will have many 1's and 0's tightly intermixed, but silence may have larger spaces uniformly filled with all 1's or all 0's or all 0101's or some such. Any repetitive pattern has less entropy than a random mess. And at a non-zero absolute temperature, allowing entropy to increase can release energy. So, I think a filled player may theoretically have infinitesimally _less_ mass than a wiped player. Slight surprise there.

However, the amount will be far far less than 1 millionth of the mass of the player, so there are many wandering, breathing, variable effects (such as drying surfaces and evaporating fingerprints and [temperature-expansion + air-buoyancy] and static electric charges pulling on the scale and aging and out gassing of the rechargeable battery) that will for the foreseeable future swamp out this difference, making it un-findable, and for all practical purposes non-existent.

Jim Swenson

The short answer is, NO. But I will try to give you the reason. At its very basics information from whatever source is a sequence of "Yes" / "NO" or "1" / "0". Everything else is just a longer string of such alternatives. In principle, these signals could be the recording of (a blob) / or (not a blob).

However, such a device would shortly become so heavy that it would collapse under its own weight. An aside: Having said that inkjet printers work on this principle. Anywhere from three to eight (or more) jets spurt / or do not spurt a miniscule droplet according to the (go/no go) command by the printer. You can feel the difference in the weight of a high coverage vs. text page.

The recording of music and/or video presents a different challenge. The number of "digitized" bits of information required to produce an audio or video is astronomical compared to the printing problem above. You would need a truck to carry a single song on an MP3!!

So there has to be a different mechanism for recording ("1's") and ("0"s). There are a number of ways of doing this. One way is to align a magnetic crystal to record either a ("1") or a zero ("0")according to whether it gets a signal of ("1") or ("0"). There are optical methods of doing the same operation, but the principles are the same. If the number of ("1")'s and ("0")'s are fast enough our brains perceive the content as a continuous stream of information.

Appropriate to your original question. The information that is transferred to a recorder/play back device depends upon electronic processes, not upon the transfer of mass of material, except in special cases.

Vince Calder

No, an electronic device does not gain weight when information is added. In general, "information" does not usually have any weight if the writing medium is already physically present. In electronic memory devices, when you add information, the random or nonsensical bits of the memory that are already there are changed to meaningful states. Not only is nothing physical added, nothing is even physically changed. The storage of information may be by magnetic or ferroelectric bits, which are associated with tiny amounts of ferroelectric or ferromagnetic materials. When information is changed, the magnetic domains may be magnetized, or the electric polarization may be changed, but no atoms or molecules are moved around or added.

Robert Erck

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