Mass of Magnetic Information
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
Nope, no weight is added. The information is stored by rearranging the
magnetic material, not by adding to it.
Hope this helps,
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.
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
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
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.
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.
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.
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Update: June 2012