Author Topic: Episode #760  (Read 258 times)

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Offline Belgarath

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Episode #760
« on: February 15, 2020, 09:49:05 am »


What's the Word: Ablation

News Items:

Does Information have Mass,
Fight Fat with Salt and Ice,
Where Does Poop Go,
Solar Scam

Who's That Noisy

Your Questions and E-mails: Kinesio Tape
Science or Fiction
#non-belief denialist

Offline RMoore

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Re: Episode #760
« Reply #1 on: February 18, 2020, 01:32:40 pm »
The relationship between information, energy, and entropy is fascinating and would make for a good interview topic. It would be great to hear either Sean Carroll or Benjamin Schumacher on this topic.

As to the suggestion of weighing a disk drive with and without information recorded on the media, forget about detecting a difference. The Boltzmann constant relates energy to information by a factor on the order of 10-23 joules per bit per degree Kelvin. So the data (recorded information) filling a terabyte drive at room temperature has energy on the order 10-8 Joules. Divide that number by the speed of light (3*108 meters/second) squared to convert joules to kilograms, and you see that it is a very tiny mass, such that a measurement will get lost in the noise. But the issue is more subtle than that, because the real information we need to consider is the microstate information -- the specification of position and momentum of each particle making up the drive. Even the unwritten bit domains on the medium have structure. Writing or erasing a bit changes the macrostate information, but the change in microstate information that this entails is not so readily quantifiable. To complicate it even more, when we write or erase data on a disk, we aren't changing the bits from unwritten to one or zero (or back to unwritten); we are overwriting the bits, flipping the value of each between 0 and 1. And a bit that is set to 0 contains the same amount of information as a bit that is set to 1 (whether or not the information is meaningful is a separate question, one of semantics).

Claude Shannon was a fascinating individual. Fortune's Formula, by William Poundstone, is a good introduction to Shannon and his colleagues Ed Thorp and John Kelly, and to an interesting application of information theory.

Offline daniel1948

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Re: Episode #760
« Reply #2 on: February 18, 2020, 03:25:02 pm »
The relationship between information, energy, and entropy ...

Thank you for posting that. Very interesting!
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Offline fuzzyMarmot

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Re: Episode #760
« Reply #3 on: February 20, 2020, 12:36:07 am »
The relationship between information, energy, and entropy is fascinating and would make for a good interview topic. It would be great to hear either Sean Carroll or Benjamin Schumacher on this topic.

As to the suggestion of weighing a disk drive with and without information recorded on the media, forget about detecting a difference. The Boltzmann constant relates energy to information by a factor on the order of 10-23 joules per bit per degree Kelvin. So the data (recorded information) filling a terabyte drive at room temperature has energy on the order 10-8 Joules. Divide that number by the speed of light (3*108 meters/second) squared to convert joules to kilograms, and you see that it is a very tiny mass, such that a measurement will get lost in the noise. But the issue is more subtle than that, because the real information we need to consider is the microstate information -- the specification of position and momentum of each particle making up the drive. Even the unwritten bit domains on the medium have structure. Writing or erasing a bit changes the macrostate information, but the change in microstate information that this entails is not so readily quantifiable. To complicate it even more, when we write or erase data on a disk, we aren't changing the bits from unwritten to one or zero (or back to unwritten); we are overwriting the bits, flipping the value of each between 0 and 1. And a bit that is set to 0 contains the same amount of information as a bit that is set to 1 (whether or not the information is meaningful is a separate question, one of semantics).

Claude Shannon was a fascinating individual. Fortune's Formula, by William Poundstone, is a good introduction to Shannon and his colleagues Ed Thorp and John Kelly, and to an interesting application of information theory.

Another great pop sci read on this topic is "The Information: A History, A Theory, A Flood" by James Gleick.

Offline jt512

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Re: Episode #760
« Reply #4 on: February 20, 2020, 01:54:16 am »
As to the suggestion of weighing a disk drive with and without information recorded on the media, forget about detecting a difference. The Boltzmann constant relates energy to information by a factor on the order of 10-23 joules per bit per degree Kelvin. So the data (recorded information) filling a terabyte drive at room temperature has energy on the order 10-8 Joules. Divide that number by the speed of light (3*108 meters/second) squared to convert joules to kilograms, and you see that it is a very tiny mass, such that a measurement will get lost in the noise. But the issue is more subtle than that, because the real information we need to consider is the microstate information -- the specification of position and momentum of each particle making up the drive. Even the unwritten bit domains on the medium have structure. Writing or erasing a bit changes the macrostate information, but the change in microstate information that this entails is not so readily quantifiable. To complicate it even more, when we write or erase data on a disk, we aren't changing the bits from unwritten to one or zero (or back to unwritten); we are overwriting the bits, flipping the value of each between 0 and 1. And a bit that is set to 0 contains the same amount of information as a bit that is set to 1 (whether or not the information is meaningful is a separate question, one of semantics).


So, if I take a hard drive, all of whose bits have been set to 0, and then randomize each bit to either 0 or 1, there are physicist who think that I have increased the mass of the hard drive?  Seriously?  I'm gonna guess this is a fringe theory.
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Offline bachfiend

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Re: Episode #760
« Reply #5 on: February 20, 2020, 05:54:28 am »
As to the suggestion of weighing a disk drive with and without information recorded on the media, forget about detecting a difference. The Boltzmann constant relates energy to information by a factor on the order of 10-23 joules per bit per degree Kelvin. So the data (recorded information) filling a terabyte drive at room temperature has energy on the order 10-8 Joules. Divide that number by the speed of light (3*108 meters/second) squared to convert joules to kilograms, and you see that it is a very tiny mass, such that a measurement will get lost in the noise. But the issue is more subtle than that, because the real information we need to consider is the microstate information -- the specification of position and momentum of each particle making up the drive. Even the unwritten bit domains on the medium have structure. Writing or erasing a bit changes the macrostate information, but the change in microstate information that this entails is not so readily quantifiable. To complicate it even more, when we write or erase data on a disk, we aren't changing the bits from unwritten to one or zero (or back to unwritten); we are overwriting the bits, flipping the value of each between 0 and 1. And a bit that is set to 0 contains the same amount of information as a bit that is set to 1 (whether or not the information is meaningful is a separate question, one of semantics).


So, if I take a hard drive, all of whose bits have been set to 0, and then randomize each bit to either 0 or 1, there are physicist who think that I have increased the mass of the hard drive?  Seriously?  I'm gonna guess this is a fringe theory.

Yes, you will increase the mass of the hard drive, even if only for the short term.  Changing the value of half of the bits in the hard drive will cause it to become warmer.  The constituent atoms will be moving slightly faster and their mass will be slightly greater owing to special relativity.  Owing to inefficiency of the hard ware.

Information doesn’t weigh anything, but heat does.
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Offline daniel1948

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Re: Episode #760
« Reply #6 on: February 20, 2020, 12:30:53 pm »
As to the suggestion of weighing a disk drive with and without information recorded on the media, forget about detecting a difference. The Boltzmann constant relates energy to information by a factor on the order of 10-23 joules per bit per degree Kelvin. So the data (recorded information) filling a terabyte drive at room temperature has energy on the order 10-8 Joules. Divide that number by the speed of light (3*108 meters/second) squared to convert joules to kilograms, and you see that it is a very tiny mass, such that a measurement will get lost in the noise. But the issue is more subtle than that, because the real information we need to consider is the microstate information -- the specification of position and momentum of each particle making up the drive. Even the unwritten bit domains on the medium have structure. Writing or erasing a bit changes the macrostate information, but the change in microstate information that this entails is not so readily quantifiable. To complicate it even more, when we write or erase data on a disk, we aren't changing the bits from unwritten to one or zero (or back to unwritten); we are overwriting the bits, flipping the value of each between 0 and 1. And a bit that is set to 0 contains the same amount of information as a bit that is set to 1 (whether or not the information is meaningful is a separate question, one of semantics).


So, if I take a hard drive, all of whose bits have been set to 0, and then randomize each bit to either 0 or 1, there are physicist who think that I have increased the mass of the hard drive?  Seriously?  I'm gonna guess this is a fringe theory.

Actually, by randomizing the bits, I think you've reduced the amount of information and decreased the mass of the HD.  ;)
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Offline jt512

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Re: Episode #760
« Reply #7 on: February 20, 2020, 09:49:38 pm »
As to the suggestion of weighing a disk drive with and without information recorded on the media, forget about detecting a difference. The Boltzmann constant relates energy to information by a factor on the order of 10-23 joules per bit per degree Kelvin. So the data (recorded information) filling a terabyte drive at room temperature has energy on the order 10-8 Joules. Divide that number by the speed of light (3*108 meters/second) squared to convert joules to kilograms, and you see that it is a very tiny mass, such that a measurement will get lost in the noise. But the issue is more subtle than that, because the real information we need to consider is the microstate information -- the specification of position and momentum of each particle making up the drive. Even the unwritten bit domains on the medium have structure. Writing or erasing a bit changes the macrostate information, but the change in microstate information that this entails is not so readily quantifiable. To complicate it even more, when we write or erase data on a disk, we aren't changing the bits from unwritten to one or zero (or back to unwritten); we are overwriting the bits, flipping the value of each between 0 and 1. And a bit that is set to 0 contains the same amount of information as a bit that is set to 1 (whether or not the information is meaningful is a separate question, one of semantics).


So, if I take a hard drive, all of whose bits have been set to 0, and then randomize each bit to either 0 or 1, there are physicist who think that I have increased the mass of the hard drive?  Seriously?  I'm gonna guess this is a fringe theory.

Actually, by randomizing the bits, I think you've reduced the amount of information and decreased the mass of the HD.  ;)

No, it's actually the other way around, oddly enough.  See the comment section here, especially the comments by Daniel Hawkins.
« Last Edit: February 23, 2020, 12:48:43 am by jt512 »
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Offline fuzzyMarmot

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Re: Episode #760
« Reply #8 on: February 23, 2020, 12:46:09 am »
This all seems to be a recapitulation of the validity of Landauer's Principle.
Here is an excellent overview, with discussion of often overlooked nuances:

https://arxiv.org/abs/1901.10327