scientific question on computer mass

[yellowcat]

this may help answer a question i asked at a dinner party but i did not know the answer

if you buy a computer and weigh it
then install shed loads of software
will it's mass increase?

cheers

[The Texan]

why would it increase the weight of your pc? are you assuming your hard drive would actually weigh more when you install programs on it? I dont know for sure, but I doubt that....

[bagggi]

aaahhhh.....

nope.

thats why its called software. hardware-weighs, software-dont weigh.

its kinda hard to explain.

to understand this, you have to come down to real basics of computers.

take a hard disk. hard disk has sectors on it. it has values which "change" from zeros to ones. now you install an operating system. the operating system is designed to read these sectors of the hard disk. thats how it comes to know how much hard disk space has been used.

when you install something it just changes the value on the hard disk. now the operating system "understands" this as space used.

so you see, you are now adding any "weight" on it, you are just changing the "values"

thats all.

[hexadecimal]

software is an electrical charge. all software is, is electricity aranged in a certain way... energy has no mass.

problem solved

but if you leave the cd witht he software in your computer when you weigh it.. yes the mass will change SLIGHTLY

[nihil]

Hmmm,

By loading a lot of software you are running the computer. The fans will suck in dust from the environment, which will cause the weight to increase slightly in practical terms.

However, if you just turned the computer on and left it at the logon screen, the fans would still be turning, but no software was loaded and the same increase in weight would occur.

So, if you wanted to be really pedantic you could argue that the weight would increase, but there would be no direct causal link to the software.

Best weight increase I have seen was when I was fixing an old Compaq Pressario 486/66. I popped the case and found that a 2.5" wolf spider had taken up residence

[er0k]

nihil.. you have far too many posts

[dmorgan]

Ha HA!

energy has no mass.

Energy does have mass, but go into that and we are talking Einstien's general relativity.
just had to throw that in there.

[nihil]

Don't be afraid, er0k and myself are working on a digitally remixed version of the Phlogiston Theory to handle the new observations and technology.

[sec_ware]

Hi

Einstien's general relativity.

Actually, we are talking his special relativity , E^2 = (m c^2)^2 + (p c)^2,
which simplifies to E=m c^2 for p=0

So, this is my feeble attempt on a scientific explanation ...

Does the energy content of the harddisk change?

As said by baggi, installation of software changes the "values" of
so-called "bit-cells" from 0 (no magnetic transition within the "bit cell")
to 1 (magnetic transition within the "bit cell") or vice versa.

In each "bit cell", there are lots of "grains" (due to the need of error reduction) -
each "grain" is a little magnet, whose magnetisation can be flipped via the write
head of the harddisk. See for some pictures[1].
Thus, installing software flips the magnetisation of "grains" in a particular
manner, such that the "bit cell" has or has not a magnetic transition, hence
representing the installed software in a chain of 0 - 1 - 1 - 1 - 0 - 0 - ...


Now, does the overall energy (or "mass" if you wish) change?


Szenario A: "groundstate"

Assume the harddisk is in a state 0 - 0 - 0 - 0 - 0 - 0 - ... this corresponds
to the fact that all "grains" have the same magnetisation (almost at least),
hence there are no magnetic transitions (or magnetic interfaces), ie there is no
boundary at which at the "left" there are "grains" with a "negative" magnetisation,
and at the "right" there are "grains" with a "positive" magnetisation. This
state is a state of minimal energy E_0 (creating magnetic interfaces cost energy!).

Now if you switch some of the 0 to 1, like to 0 - 1 - 1 - 0 - 0 - 0 - ..., you
have created two magnetic transitions (two magnetic interfaces), which requires
energy. The overall energy of the harddisk has been increased from E_0 -> E_0 + 2 * E_I,
where E_I is the energy required to build an interface


Szenario B: "reality"

In reality the state of the harddisk corresponds to an almost random chain
0 - 1 - 1 - 0 - 1 - 0 - ... Installing software will
alter this chain to another chain, which again, is usually almost random.
Overall, the energy content of the harddisk thus will not change.
(I have used "almost" and "usually" consiously )

Cheers


[1¨http://www.hitachigst.com/hdd/resear...ge/pm/pm1.html

[fourdc]

I would think ones weighed more than zeros.

If you save documents in smaller fonts would it save space and weight?

We need to get to the bottom of this. I'd research it but I'm still trying to find out if the light in the fridge really goes out when I shut the door.