"Love is a matter of chemistry, but Sex is a matter of physics"

anonymous  (via fuckyeahelements)
Here is another way to justify how humans are “central” in this universe. 

Consider the range in size of what is physically relevant in our universe. This range spans about 60 orders of magnitude (1060) from the size of the visible universe at about 13.7 billion light years (~1028 cm) all the way down to the Planck length, which is the smallest scale in which notions of size and distance essentially breakdown according to standard theories, at ~10-33 cm. As humans, at about 102 cm in size, we happen to exist near the middle of this range. This really is no coincidence, nor is it some kind of trickery with units of measurement.
It can be argued that if humans were any smaller our brains wouldn’t have room to develop their complexity allowing for our intelligence, and if we were any bigger our brains would lose their practical efficiency which depends on the brain’s ability to interact with itself. In fact, this must be true for all intelligent life. So if you ever happen to feel down about your size relative to the rest of the universe, know that you are much more significant than any other structure in this universe  exactly the way you are. Even David Deutsch once wrote: “The size of the universe is no more depressing than the size of a cow.”However, it does seem rather peculiar that we humans exist and are making these observations of size at the point in time when the Universe has expanded to its current size, which just so happens to place us in the middle of this size range. Couldn’t this have been any different? On the other end of things, one may even be willing to pass the size scale set by the Plank length as being mere coincidence, since the fundamental constants which determine its value could have possibly taken on different values themselves making things very different.

Here is another way to justify how humans are “central” in this universe. 


Consider the range in size of what is physically relevant in our universe. This range spans about 60 orders of magnitude (1060) from the size of the visible universe at about 13.7 billion light years (~1028 cm) all the way down to the Planck length, which is the smallest scale in which notions of size and distance essentially breakdown according to standard theories, at ~10-33 cm.

As humans, at about 102 cm in size, we happen to exist near the middle of this range. This really is no coincidence, nor is it some kind of trickery with units of measurement.

It can be argued that if humans were any smaller our brains wouldn’t have room to develop their complexity allowing for our intelligence, and if we were any bigger our brains would lose their practical efficiency which depends on the brain’s ability to interact with itself. In fact, this must be true for all intelligent life.

So if you ever happen to feel down about your size relative to the rest of the universe, know that you are much more significant than any other structure in this universe  exactly the way you are. Even David Deutsch once wrote: “The size of the universe is no more depressing than the size of a cow.”

However, it does seem rather peculiar that we humans exist and are making these observations of size at the point in time when the Universe has expanded to its current size, which just so happens to place us in the middle of this size range. Couldn’t this have been any different?

On the other end of things, one may even be willing to pass the size scale set by the Plank length as being mere coincidence, since the fundamental constants which determine its value could have possibly taken on different values themselves making things very different.



Stirling Engines


Stirling engines are unique heat engines because their theoretical efficiency is nearly equal to their theoretical maximum efficiency, known as the Carnot Cycle efficiency. Stirling engines are powered by the expansion of a gas when heated, followed by the compression of the gas when cooled. The Stirling engine contains a fixed amount of gas that is transferred back and forth between a “cold” end (often room temperature) and a “hot” end (often heated by a kerosene or alcohol burner). The “displacer piston” moves the gas between the two ends and the “power piston” changes the internal volume as the gas expands and contracts.
Air in the engine is cyclically heated (by an alcohol burner) and expands to push the power piston (shown in blue) to the right. As the power piston moves to the right, the yellow linkage forces the loose-fitting, red “piston” (on the left half of the machine) to displace air to the cooler side of the engine. The air on the cool side loses heat to the outside world and contracts, pulling the blue piston to the left. The air is again displaced, sending it back to the hotter region of the engine, and the cycle repeats.
The Stirling engine cycle can also be used “in reverse”, to convert rotating motion into a temperature differential (and thus provide refrigeration).

Stirling Engines

Stirling engines are unique heat engines because their theoretical efficiency is nearly equal to their theoretical maximum efficiency, known as the Carnot Cycle efficiency. Stirling engines are powered by the expansion of a gas when heated, followed by the compression of the gas when cooled. The Stirling engine contains a fixed amount of gas that is transferred back and forth between a “cold” end (often room temperature) and a “hot” end (often heated by a kerosene or alcohol burner). The “displacer piston” moves the gas between the two ends and the “power piston” changes the internal volume as the gas expands and contracts.

Air in the engine is cyclically heated (by an alcohol burner) and expands to push the power piston (shown in blue) to the right. As the power piston moves to the right, the yellow linkage forces the loose-fitting, red “piston” (on the left half of the machine) to displace air to the cooler side of the engine. The air on the cool side loses heat to the outside world and contracts, pulling the blue piston to the left. The air is again displaced, sending it back to the hotter region of the engine, and the cycle repeats.

The Stirling engine cycle can also be used “in reverse”, to convert rotating motion into a temperature differential (and thus provide refrigeration).

etceterablog:

Geometry from the Brockhaus and Efron Encyclopedic Dictionary, published in Russia,1890-1907.

etceterablog:

Geometry from the Brockhaus and Efron Encyclopedic Dictionary, published in Russia,1890-1907.

project-argus:

This is useful.

So beautiful. 

project-argus:

This is useful.

So beautiful. 

20 Things You Didn’t Know About The Periodic Table

How it started, how it’s like solitaire, how to fold it, and how it ends.
by Rebecca Coffey
Image above: Periodic Table by Lawrence Berkeley National Lab
1  You may remember the Periodic Table of the  Elements as a dreary chart on your classroom wall. If so, you never  guessed its real purpose: It’s a giant cheat sheet.
2  The table has served chemistry students since 1869, when it was created by Dmitry Mendeleyev, a cranky professor at the University of St. Petersburg.
3  With a publisher’s deadline looming, Mendeleyev  didn’t have time to describe all 63 then-known elements. So he turned to  a data set of atomic weights meticulously gathered by others.
4  To determine those weights, scientists had passed  currents through various solutions to break them up into their  constituent atoms. Responding to a battery’s polarity, the atoms of one  element would go thisaway, the atoms of another thataway. The atoms were  collected in separate containers and then weighed.
5  From this process, chemists determined relative weights—which were all Mendeleyev needed to establish a useful ranking.
6  Fond of card games, he wrote the weight for each  element on a separate index card and sorted them as in solitaire.  Elements with similar properties formed a “suit” that he placed in  columns ordered by ascending atomic weight.
7  Now he had a new Periodic Law (“Elements arranged  according to the value of their atomic weights present a clear  periodicity of properties”) that described one pattern for all 63  elements.
8  Where Mendeleyev’s table had blank spaces, he  correctly predicted the weights and chemical behaviors of some missing  elements—gallium, scandium, and germanium.
9  But when argon was discovered in 1894, it didn’t  fit into any of Mendeleyev’s columns, so he denied its existence—as he  did for helium, neon, krypton, xenon, and radon.
10  In 1902 he acknowledged he had not anticipated the existence of these overlooked, incredibly unreactive elements—the noble gases—which now constitute the entire eighth group of the table.
11  Now we sort elements by their number of protons,  or “atomic number,” which determines an atom’s configuration of  oppositely charged electrons and hence its chemical properties.
12  Noble gases (far right on the periodic table) have closed shells of electrons, which is why they are nearly inert.
13  Atomic love: Take a modern periodic table, cut  out the complicated middle columns, and fold it once along the middle of  the Group 4 elements. The groups that kiss have complementary electron  structures and will combine with each other.
14  Sodium touches chlorine—table salt! You can predict other common compounds like potassium chloride, used in very large doses as part of a lethal injection.
15  The Group 4 elements (shown as IVA above) in the  middle bond readily with each other and with themselves. Silicon +  silicon + silicon ad infinitum links up into crystalline lattices, used  to make semiconductors for computers.
16  Carbon atoms—also Group 4—bond in long chains,  and voilà: sugars. The chemical flexibility of carbon is what makes it  the key molecule of life.
17  Mendeleyev wrongly assumed that all elements are  unchanging. But radioactive atoms have unstable nuclei, meaning they  can move around the chart. For example, uranium (element 92) gradually  decays into a whole series of lighter elements, ending with lead  (element 82).
18  Beyond the edge: Atoms with atomic numbers  higher than 92 do not exist naturally, but they can be created by  bombarding elements with other elements or pieces of them.
19  The two newest members of the periodic table,  still-unnamed elements 114 and 116, were officially recognized last  June. Number 116 decays and disappears in milliseconds. (Three elements,  110 to 112, were also officially named earlier this month.)
20  Physicist Richard Feynman once predicted that number 137 defines the table’s outer limit; adding  any more protons would produce an energy that could be quantified only  by an imaginary number, rendering element 138 and higher impossible.  Maybe.

20 Things You Didn’t Know About The Periodic Table

How it started, how it’s like solitaire, how to fold it, and how it ends.

by Rebecca Coffey

Image above: Periodic Table by Lawrence Berkeley National Lab

1  You may remember the Periodic Table of the Elements as a dreary chart on your classroom wall. If so, you never guessed its real purpose: It’s a giant cheat sheet.

2  The table has served chemistry students since 1869, when it was created by Dmitry Mendeleyev, a cranky professor at the University of St. Petersburg.

 With a publisher’s deadline looming, Mendeleyev didn’t have time to describe all 63 then-known elements. So he turned to a data set of atomic weights meticulously gathered by others.

4  To determine those weights, scientists had passed currents through various solutions to break them up into their constituent atoms. Responding to a battery’s polarity, the atoms of one element would go thisaway, the atoms of another thataway. The atoms were collected in separate containers and then weighed.

 From this process, chemists determined relative weights—which were all Mendeleyev needed to establish a useful ranking.

6  Fond of card games, he wrote the weight for each element on a separate index card and sorted them as in solitaire. Elements with similar properties formed a “suit” that he placed in columns ordered by ascending atomic weight.

7  Now he had a new Periodic Law (“Elements arranged according to the value of their atomic weights present a clear periodicity of properties”) that described one pattern for all 63 elements.

 Where Mendeleyev’s table had blank spaces, he correctly predicted the weights and chemical behaviors of some missing elements—gallium, scandium, and germanium.

 But when argon was discovered in 1894, it didn’t fit into any of Mendeleyev’s columns, so he denied its existence—as he did for helium, neon, krypton, xenon, and radon.

10  In 1902 he acknowledged he had not anticipated the existence of these overlooked, incredibly unreactive elements—the noble gases—which now constitute the entire eighth group of the table.

11  Now we sort elements by their number of protons, or “atomic number,” which determines an atom’s configuration of oppositely charged electrons and hence its chemical properties.

12  Noble gases (far right on the periodic table) have closed shells of electrons, which is why they are nearly inert.

13  Atomic love: Take a modern periodic table, cut out the complicated middle columns, and fold it once along the middle of the Group 4 elements. The groups that kiss have complementary electron structures and will combine with each other.

14  Sodium touches chlorine—table salt! You can predict other common compounds like potassium chloride, used in very large doses as part of a lethal injection.

15  The Group 4 elements (shown as IVA above) in the middle bond readily with each other and with themselves. Silicon + silicon + silicon ad infinitum links up into crystalline lattices, used to make semiconductors for computers.

16  Carbon atoms—also Group 4—bond in long chains, and voilà: sugars. The chemical flexibility of carbon is what makes it the key molecule of life.

17  Mendeleyev wrongly assumed that all elements are unchanging. But radioactive atoms have unstable nuclei, meaning they can move around the chart. For example, uranium (element 92) gradually decays into a whole series of lighter elements, ending with lead (element 82).

18  Beyond the edge: Atoms with atomic numbers higher than 92 do not exist naturally, but they can be created by bombarding elements with other elements or pieces of them.

19  The two newest members of the periodic table, still-unnamed elements 114 and 116, were officially recognized last June. Number 116 decays and disappears in milliseconds. (Three elements, 110 to 112, were also officially named earlier this month.)

20  Physicist Richard Feynman once predicted that number 137 defines the table’s outer limit; adding any more protons would produce an energy that could be quantified only by an imaginary number, rendering element 138 and higher impossible. Maybe.

Q&BA: How does a gravitational slingshot work?

In this episode of Q&BA, I describe how a gravitational slingshot works, and how they are used to get spacecraft to the inner and outer solar system.

by TheBadAstronomer

black-tangled-heart:

Google Celebrates Heinrich Rudolf Hertz Birthday
One of the pillars of the “Electromagnetic Theory of Light,” German physicist Heinrich Rudolf Hertz is the center of the Google universe today, February 22nd (Australian Time) with his own Google Doodle. According to Google, the new Doodle celebrates the 155th birthday of Heinrich Rudolf Hertz.

black-tangled-heart:

Google Celebrates Heinrich Rudolf Hertz Birthday

One of the pillars of the “Electromagnetic Theory of Light,” German physicist Heinrich Rudolf Hertz is the center of the Google universe today, February 22nd (Australian Time) with his own Google Doodle. According to Google, the new Doodle celebrates the 155th birthday of Heinrich Rudolf Hertz.