How much does software weigh?

I've seen the anecdotes on the net, but seriously: surely everything
has a specific quantifiable weight even at an atomic / molecular
level. Interestingly enough (for me, at least), if saving software
cuts grooves into the hard disk or CD, then the disk or CD loses
weight as a consequence. So the act of storing software has a negative
impact on its own weight.

Hello davidbrent and thank you for your question.

Actually, no, software does not weigh anything.  When you save a
program or file on a disk, all you are doing is rearranging the
magnetic surface of the disk ie, you are not adding anything or taking
anything away

"If I take a blank computer disk and weight it on a scale, it will
weigh about 0.7 oz. If I spend hundreds of dollars and load it with
over a million bytes of software, it will still weigh 0.7 oz. Software
has no mass. Although it may be resident in a physical system, it has
no mass of its own. It can even be transmitted through the airwaves."
http://www.khouse.org/articles/technical/20031201-498.html#notes

"Software has no mass ? you cannot see, touch, feel, weigh, smell, or
hear it. As such, software is often misunderstood, ignored, or
confused with its hardware because it has no physical properties.
People have trouble understanding something that is invisible, exists
in an ethereal world of magnetic fields and electronic bits and bytes.
Theoretically, because it is intangible ? it has none of the physical
properties that cause physical systems to age and break down ? it will
never wear out. Also theoretically, software could last forever!
Because software is intangible, it can be designed; but it cannot be
built in any physical way."
http://216.239.51.104/search?q=cache:bDqV8QzWCx8J:www.stsc.hill.af.mil/resources/tech_docs/gsam3/chap1.pdf+%22software+has+no+mass%22&hl=en

"Software has no mass or physicality
It is ?thought stuff? (Fred Brooks Jr.)
i.e., purely intellectual"
http://roots.dnd.no/downloads/2002/OCallaghan_Alan/Human_Centred_Design_-_ROOTS_2002.pps.

And to finish, an amusing (I think so anyway) ditty.
"Your customers are gravitating toward Microsoft server software."

Since software has no mass, I don't believe it can have gravity, thus
we must look elsewhere for an explanation of this phenomenon.  Can this
be the first public admission by Microsoft that their software actually
sucks?"
http://raven.utc.edu/cgi-bin/WA.EXE?A2=ind9812e&L=hp3000-l&F=&S=&P=9673

Thank you for your question, and if you need any clarification
regarding my answer, do not hesitate to ask.

Very best regards

THX1138

Search strategy included:
software mass weight
://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&as_qdr=all&q=software++mass++weight&btnG=Search

I'm not sure but when hard drive is written,it changes its magnetic
fields and so its energy.And the mass of the body depends on its full
energy(E=mc2) and maybe hard drive becomes more or less heavy.By the
way, the light or electromagnetic waves also have a mass(but very
small) .
And CD recording  doesn't cut grooves on it,it just changes its chemical structure.