Author: Physics for Bunnies

just–space:

just–space:

The Aurora and the Sunrise : On the International Space Station (ISS), you can only admire an aurora until the sun rises. Then the background Earth becomes too bright. Unfortunately, after sunset, the rapid orbit of the ISS around the Earth means that sunrise is usually less than 47 minutes away. In the featured image, a green aurora is visible below the ISS – and on the horizon to the upper right, while sunrise approaches ominously from the upper left. Watching an aurora from space can be mesmerizing as its changing shape has been compared to a giant green amoeba. Auroras are composed of energetic electrons and protons from the Sun that impact the Earth’s magnetic field and then spiral down toward the Earth so fast that they cause atmospheric atoms and molecules to glow. The ISS orbits at nearly the same height as auroras, many times flying right through an aurora’s thin upper layers, an event that neither harms astronauts nor changes the shape of the aurora. via NASA

A copy of the essay "This is Not Cold Fus…

A copy of the essay "This is Not Cold Fusion" you mentioned recently is posted under SEPTEMBER 2018 on the Cryptome home page. (Sorry, this posting software won't let me include the link.) The essay won second prize in the 2018 US Naval Institute Emerging/Disruptive Technologies Essay Contest.

👌 Cheers

The U.S. Naval Institute (USNI) just published…

The U.S. Naval Institute (USNI) just published an essay in "Proceedings" on "low energy nuclear reactions." THe essay endorses the "Widom-Larsen Theory" of LENR. This "essay" actually won second prize in USNI's 2018 "Emerging Technologies" essay contest. Quite frankly, I can't see this "technology" emerging anytime or anywhere. Comments?

Apologies for the very late reply. I haven’t come across this essay and i’m not a nuclear physicist, but i can comment this: low energy nuclear reactions are a relevant topic. If the “proceedings” they present allow, for example, to extract a great quantity of energy from a low energy reaction, i guess that maybe this technology could be applicable in some fields. Idk, to have a relevant comment i would need understand what that technology is.

Is information something real?

furioustimemachinebarbarian:

physicsforbunnies:

Normally one speaks of living things as beings that consume energy to survive and proliferate. This is of course not correct; energy is conserved, and cannot be consumed. Living beings intercept entropy flows; they use low-entropy sources of energy and emit high entropy forms of the same energy (body heat).

Can we burn information as fuel? Consider a really frugal digital memory tape, with one atom used to store each bit:

The position of a single ideal gas atom denotes a bit. If it is in the top half of a partitioned box, the bit is one, otherwise it is zero. The side walls of the box are pistons, which can be used to set, reset, or extract energy from the stored bits. The numbers above the boxes are not a part of the tape, they just denote what bit is stored in a given position.

The tape is a series of boxes, with each box containing one ideal gas atom. The box is split into two equal pieces by a removable central partition. If the atom is in the top half of the box, the tape reads one; if it is in the bottom half the tape reads zero. The side walls are frictionless pistons that may be used to push the atom around. If we know the atom position in the n-th box, we can move the other side wall in, remove the partition, and gradually retract the piston to its original position destroying our information about where the atom is, but extracting useful work.

Extracting energy from a known bit is a three-step process: compress the empty half of the box, remove the partition, and retract the piston and extract PdV work out of the ideal gas atom. (One may then restore the partition to return to an equivalent, but more ignorant, state.) In the process, one loses one bit of information (which side of the the partition is occupied).

A memory tape can therefore be used to power an engine. If the engine knows or can guess the sequence written on the tape, it can extract useful work in exchange for losing that information.

Reference: 

Statistical Mechanics,  J. Sethna

This is an old post that is bouncing around, but it’s not actually true.  The memory tape is not powering the engine, the gas in the chamber is.  Or, if your gas is in thermal contact with a heat reservoir with some temperature T, you’re extracting work from the reservoir (T ln 2 of work).  

What you have done is run an engine without a cold reservoir.  Which is interesting!  The relationship to information is entropy, not information.  We can’t burn information as fuel, but we can use information to extract work we’d otherwise not be able to.  This seems maybe really pedantic, but it’s super important. The correspondence between information and entropy is quite deep. 

Since this post is getting some attention, comments and questions, I suggest you guys have a look at the reference at the bottom of the text, that will explain the matter better than any tumblr post.

amore-more-ore-re: physicsforbunnies:Carl Jun…

amore-more-ore-re:

physicsforbunnies:

Carl Jung

So the loneliness created by his own pride is satanic.
The pride of believing that our thoughts are more important than those of others.
Pride is to cut oneself off from others.
The proud man creates his own Hell on Earth.

Fuck off

Carl Jung

Carl Jung

Summer schools be like

Summer schools be like

Regular

imsureiforgotsomething:

physicsforbunnies:

physicsforbunnies:

I’ve been thinking about this for days but… Chemistry really is just a branch of physics which has been historically separated from it because quantum mechanics and the finer detailes of atomic physics are relatively recent discoveries.

What i’m saying is that chemistry is clumsy physics. A vulgar version of physics. F*ck chemistry.

Guys… The second part of this post was obviously sarcastic. Did I really need to write this down. Fucking chill.

source

Basically

Regular

physicsforbunnies:

I’ve been thinking about this for days but… Chemistry really is just a branch of physics which has been historically separated from it because quantum mechanics and the finer detailes of atomic physics are relatively recent discoveries.

What i’m saying is that chemistry is clumsy physics. A vulgar version of physics. F*ck chemistry.

Guys… The second part of this post was obviously sarcastic. Did I really need to write this down. Fucking chill.

Regular

chemistry-corner:

physicsforbunnies:

I’ve been thinking about this for days but… Chemistry really is just a branch of physics which has been historically separated from it because quantum mechanics and the finer detailes of atomic physics are relatively recent discoveries.

What i’m saying is that chemistry is clumsy physics. A vulgar version of physics. F*ck chemistry.

So I am reblogging this, because I want to be reminded that People like this exist, but understandably I won’t like it because it is, obviously, as wrong as a 35 year old guy luring Children with candy into his white Van.

What kind of lab fumes have you been inhaling, my child.