| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
03 Apr 2006 01:06:43 PM |
| Object: |
Difference between Chemistry and Physics |
Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject? Can someone refer me
to sources which talk about this?
Thank you,
Craig
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| User: "" |
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| Title: Re: Difference between Chemistry and Physics |
07 Apr 2006 11:48:31 AM |
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wrote:
Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject?
Yes, once upon a time, people thought Physics
had something to do with math, and chemistry
had something to do with chemicals.
But in the twentieth century, they both
sponaneoustly converged into
Thomas Edison's *****.
Can someone refer me
to sources which talk about this?
Thank you,
Craig
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| User: "PD" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 10:59:55 AM |
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wrote:
Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject? Can someone refer me
to sources which talk about this?
Thank you,
Craig
Actually, this is probably a historical misconception. In the past,
chemistry and physics were thought of as being much the same subject
matter. Rutherford won a Nobel in chemistry. Most of the folks in the
18th and 19th centuries who worked laboriously in thermodynamics
(Gibbs, Kelvin, Carnot, Boltzmann) thought of themselves as much
chemists as physicists.
If anything, the division between them became stronger only recently,
though connected by a strong overlap that is called chemical physics or
physical chemistry, depending on which department the researcher works
in. :>)
PD
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| User: "tadchem" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 05:40:06 PM |
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PD wrote:
Actually, this is probably a historical misconception. In the past,
chemistry and physics were thought of as being much the same subject
matter. Rutherford won a Nobel in chemistry.
Marie Curie won Nobels in Chemistry *and* Physics - the first double
Nobel laureate IIRC.
Tom Davidson
Richmond, VA
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| User: "Mathias Rocher" |
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| Title: Re: Difference between Chemistry and Physics |
11 Apr 2006 07:43:18 AM |
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tadchem (Tom Davidson) wrote :
Marie Curie won Nobels in Chemistry *and* Physics - the first double
Nobel laureate IIRC.
That's true, and the most surprising in it is that her first Nobel
Prize in Chemistry concerns something that is now considered as being
physics, and not chemistry !
In fact the "ancient" definition of chemistry as being the science of
"the properties and transformation of matter", has been replaced quite
recently by a more restrictive definition that considers only the
transformations where electrons are involved. It creates two kind of
limitations (at least, it's not exhaustive) :
* the study of radioactive materials is now considered as physics
because it concerns the nucleus and not the electronic cloud ;
* the chemists (and physicists) sometimes make a funny distinction
between "physical" and "chemical" phenomena, for exemple when a
compound is adsorbed on a surface, chemists (and physicists) will say
it is "chemically adsorbed" if there is a bond that they consider as
being "chemical" (covalent, H-bonding...), whereas they will say that
it is "physically adsorbed" if the "bonding" (even this word is banned)
is mechanical or governed by Van der Waals interactions.
When did this distinction appears ? well, it could only appears when
the existence of the electron was widely accepted, so after the birth
of quantum physics...
--
Mathias Rocher
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| User: "Mark Kness" |
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| Title: Re: Difference between Chemistry and Physics |
06 Apr 2006 09:46:37 PM |
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wrote:
Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject? Can someone refer me
to sources which talk about this?
I don't have any sources, but before the 20th century or so, there was
little to no understanding of the physical basis of the chemical
behavior of things. Quantum mechanics was unknown, and even the
existence of atoms was not universally accepted.
Nowadays, chemistry can be understood from the laws of physics, i.e.
quantum mechanics gives you the hydrogen atom orbitals, molecular
orbitals, and bonding and lots of things can be understood from that.
So, now, it makes perfect sense to think of chemistry as being built
atop physics.
100-150 years ago, without this understanding of the basics, the
connection was much less clear.
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| User: "tadchem" |
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| Title: Re: Difference between Chemistry and Physics |
07 Apr 2006 03:57:09 PM |
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wrote:
Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject? Can someone refer me
to sources which talk about this?
They have *always* been subfields of "natural philosophy"
http://en.wikipedia.org/wiki/History_of_science
From an analytical POV, one cannot 'do chemistry' without knowing a lot
of physics, but one can 'do physics' without knowing a lot of
chemistry. This makes chemistry a sub-field of physics. Because it is
so accessible to intelligent chemical-based life forms it is important
enough to deserve a *huge* amount of study. The Chemical Abstracts
Service, for example, registers several million novel and unique
chemicals *each year.*
From a practical POV, chemistry concerns itself mainly with atoms and
their interactions to make more complex structures (molecules, ions,
crystals, substances, solutions, etc.)
To a physicist, these considerations are minor. Fields like particle
physics (things smaller than atoms) cosmology (things larger than
mountains or oceans) and relativity (things moving *VERY* fast) are
very important to physicists but of little interest to chemists.
Tom Davidson
Richmond, VA
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| User: "" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 02:34:04 PM |
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tadchem wrote:
[snip]
From an analytical POV, one cannot 'do chemistry' without knowing a lot
of physics, but one can 'do physics' without knowing a lot of
chemistry. This makes chemistry a sub-field of physics.
Could you expand on this? How do you need to know a lot of physics in
order to do say, a Diels-Alder reaction?
[snip]
Tom Davidson
Richmond, VA
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| User: "tadchem" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 05:34:21 PM |
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wrote:
tadchem wrote:
[snip]
From an analytical POV, one cannot 'do chemistry' without knowing a lot
of physics, but one can 'do physics' without knowing a lot of
chemistry. This makes chemistry a sub-field of physics.
Could you expand on this? How do you need to know a lot of physics in
order to do say, a Diels-Alder reaction?
You don't need to know physics to follow the lab manual and 'do' the
reaction, just like you don't need to know food chemistry to follow a
recipe and make bread.
If you plan to deviate from the recipe, you had best understand what is
going on or a pinch too much of salt will kill the yeast and you will
be left with matzoh.
The classic Diels-Alder reaction involves the interaction of typically
a conjugated diene (e.g. butadiene) with 4 pi electrons in the highest
occupied molecular orbital and 'dienophile' (e.g. acrolein) with 2 pi
electrons in its olefin bond.
If you wanted to extend the Diels-Alder condensation to larger systems,
especially if you need to control the stereochemistry, you had best
understand the quantum mechanics of molecular orbital formation and
orbital symmetry.
Quantum mechanics - isn't that, like, physics???
Tom Davidson
Richmond, VA
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| User: "Lloyd Parker" |
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| Title: Re: Difference between Chemistry and Physics |
11 Apr 2006 04:04:59 AM |
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In article <1144708461.736915.308500@t31g2000cwb.googlegroups.com>,
"tadchem" <tadchem@comcast.net> wrote:
john.spevacek@aspenresearch.com wrote:
tadchem wrote:
[snip]
From an analytical POV, one cannot 'do chemistry' without knowing a lot
of physics, but one can 'do physics' without knowing a lot of
chemistry. This makes chemistry a sub-field of physics.
Could you expand on this? How do you need to know a lot of physics in
order to do say, a Diels-Alder reaction?
You don't need to know physics to follow the lab manual and 'do' the
reaction, just like you don't need to know food chemistry to follow a
recipe and make bread.
If you plan to deviate from the recipe, you had best understand what is
going on or a pinch too much of salt will kill the yeast and you will
be left with matzoh.
The classic Diels-Alder reaction involves the interaction of typically
a conjugated diene (e.g. butadiene) with 4 pi electrons in the highest
occupied molecular orbital and 'dienophile' (e.g. acrolein) with 2 pi
electrons in its olefin bond.
If you wanted to extend the Diels-Alder condensation to larger systems,
especially if you need to control the stereochemistry, you had best
understand the quantum mechanics of molecular orbital formation and
orbital symmetry.
Quantum mechanics - isn't that, like, physics???
I think a lot of physical chemists would disagree. Its primary USE is for
atoms and electrons, the realm of chemistry.
Tom Davidson
Richmond, VA
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| User: "Gregory L. Hansen" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 08:23:24 PM |
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In article <1144708461.736915.308500@t31g2000cwb.googlegroups.com>,
tadchem <tadchem@comcast.net> wrote:
john.spevacek@aspenresearch.com wrote:
tadchem wrote:
[snip]
From an analytical POV, one cannot 'do chemistry' without knowing a lot
of physics, but one can 'do physics' without knowing a lot of
chemistry. This makes chemistry a sub-field of physics.
Could you expand on this? How do you need to know a lot of physics in
order to do say, a Diels-Alder reaction?
You don't need to know physics to follow the lab manual and 'do' the
reaction, just like you don't need to know food chemistry to follow a
recipe and make bread.
If you plan to deviate from the recipe, you had best understand what is
going on or a pinch too much of salt will kill the yeast and you will
be left with matzoh.
The classic Diels-Alder reaction involves the interaction of typically
a conjugated diene (e.g. butadiene) with 4 pi electrons in the highest
occupied molecular orbital and 'dienophile' (e.g. acrolein) with 2 pi
electrons in its olefin bond.
If you wanted to extend the Diels-Alder condensation to larger systems,
especially if you need to control the stereochemistry, you had best
understand the quantum mechanics of molecular orbital formation and
orbital symmetry.
Quantum mechanics - isn't that, like, physics???
So chemistry is only about seventy years old, then?
--
"For every problem there is a solution which is simple, clean and wrong."
-- Henry Louis Mencken
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| User: "Salmon Egg" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 11:46:11 PM |
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Around 1949 when I was in junior high school,, I would read about physics
and chemistry. I met an older high school chemist who liked to do analytical
chemistry. He said that he did not like physics. He was surprised that my
physics book was describing atoms protons and electrons. I later tried to
emulate him.
In truth, much of the same knowledge was imparted to students of both
chemistry and physics. The difference was mainly one of emphasis.
Quantum mechanics was the great equalizer. It appears that terminology was
different enough to prevent easy communication between physicists and
chemists. I still have trouble talking to chemists about dyes when I am
trying to think of the quantum analogs of antennas. I try to think in terms
of semiconductors, mobility of electrons on conjugated chains, doping, etc.
Chemist talk about chromophores and auxochromes. I really would like to
contact a chemist who also is an avid radio amateur (ham). Unfortunately,
computers and internet have made them endangered.
Taking chemistry as an undergraduate, before I knew much about quantum
mechanics, one lecturer was going on and on about colored compounds and
transition elements. It seemed that he knew interesting stuff of which I had
no clue. At the time, the chemistry class did not mention the Pauli
exclusion principle and how that led to the buildup of the periodic table.
To me, it is a good thing that chemistry is a branch of low energy physics.
It would probably be a good idea to replace the current introductory courses
in physics in chemistry and physics with a unified introduction to both.
Bill
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| User: "Lloyd Parker" |
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| Title: Re: Difference between Chemistry and Physics |
11 Apr 2006 04:06:48 AM |
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In article <C06082A2.21D6A%salmonegg@sbcglobal.net>,
Salmon Egg <salmonegg@sbcglobal.net> wrote:
Around 1949 when I was in junior high school,, I would read about physics
and chemistry. I met an older high school chemist who liked to do analytical
chemistry. He said that he did not like physics. He was surprised that my
physics book was describing atoms protons and electrons. I later tried to
emulate him.
In truth, much of the same knowledge was imparted to students of both
chemistry and physics. The difference was mainly one of emphasis.
Quantum mechanics was the great equalizer. It appears that terminology was
different enough to prevent easy communication between physicists and
chemists. I still have trouble talking to chemists about dyes when I am
trying to think of the quantum analogs of antennas. I try to think in terms
of semiconductors, mobility of electrons on conjugated chains, doping, etc.
Chemist talk about chromophores and auxochromes. I really would like to
contact a chemist who also is an avid radio amateur (ham). Unfortunately,
computers and internet have made them endangered.
Taking chemistry as an undergraduate, before I knew much about quantum
mechanics, one lecturer was going on and on about colored compounds and
transition elements. It seemed that he knew interesting stuff of which I had
no clue. At the time, the chemistry class did not mention the Pauli
exclusion principle and how that led to the buildup of the periodic table.
To me, it is a good thing that chemistry is a branch of low energy physics.
It would probably be a good idea to replace the current introductory courses
in physics in chemistry and physics with a unified introduction to both.
Bill
Oh goodness no. Physics bores students with a whole semester of inclined
planes and pulleys, while chemistry goes into reactions, gases, quantum
mechanics, stoichiometry, thermodynamics...
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| User: "Salmon Egg" |
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| Title: Re: Difference between Chemistry and Physics |
11 Apr 2006 05:34:17 PM |
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On 4/11/06 2:06 AM, in article e1g9l9$tv3$2@leto.cc.emory.edu, "Lloyd
Parker" <lparker@emory.edu> wrote:
Oh goodness no. Physics bores students with a whole semester of inclined
planes and pulleys, while chemistry goes into reactions, gases, quantum
mechanics, stoichiometry, thermodynamics...
Unfortunately, that may be true. But if chemists are not willing to
understand physics, or at least certain fundamentals thereof, they will
become monkey see, monkey do chemists. Such chemists can be useful but
primarily as techs.
Bill
-- Ferme le Bush
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| User: "Gregory L. Hansen" |
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| Title: Re: Difference between Chemistry and Physics |
12 Apr 2006 09:16:23 AM |
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In article <C0617CF8.21E65%salmonegg@sbcglobal.net>,
Salmon Egg <salmonegg@sbcglobal.net> wrote:
On 4/11/06 2:06 AM, in article e1g9l9$tv3$2@leto.cc.emory.edu, "Lloyd
Parker" <lparker@emory.edu> wrote:
Oh goodness no. Physics bores students with a whole semester of inclined
planes and pulleys, while chemistry goes into reactions, gases, quantum
mechanics, stoichiometry, thermodynamics...
Unfortunately, that may be true. But if chemists are not willing to
understand physics, or at least certain fundamentals thereof, they will
become monkey see, monkey do chemists. Such chemists can be useful but
primarily as techs.
Even at the freshman level chemistry students study atomic and molecular
orbitals, types of bonding, and other things specific to their topic.
They don't *derive* molecular orbitals, but they study them. That's
useful for them, but foreign to the physics student. It takes the physics
student a lot of physics classes before they get to that sort of thing.
--
"Work hard, be curious and persistent, and you will prevail." -- Howard
Schilit, "Financial Shenanigans" 2nd ed.
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| User: "Mathias Rocher" |
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| Title: Re: Difference between Chemistry and Physics |
11 Apr 2006 07:21:17 AM |
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Gregory L. Hansen wrote :
So chemistry is only about seventy years old, then?
It is not totally false that today's "molecular" chemistry (organic,
organometallic...) is based on quantum physics, a science that did not
exist or was not firmly accepted about 80 years ago. It doesn't mean
that chemistry did not exist before, but it wasn't exactly the same
science. Of course the work of chemists like Mendeleiev, Emil Fischer
or Victor Grignard was not based on quantum physics (how could it be ?)
so the way we understand it nowadays is not the same that the way they
did !
--
Mathias Rocher
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| User: "Salmon Egg" |
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| Title: Re: Difference between Chemistry and Physics |
11 Apr 2006 05:49:48 PM |
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On 4/11/06 5:21 AM, in article
1144758077.640461.168710@j33g2000cwa.googlegroups.com, "Mathias Rocher"
<mathias.rocher@hotmail.fr> wrote:
It is not totally false that today's "molecular" chemistry (organic,
organometallic...) is based on quantum physics, a science that did not
exist or was not firmly accepted about 80 years ago. It doesn't mean
that chemistry did not exist before, but it wasn't exactly the same
science. Of course the work of chemists like Mendeleiev, Emil Fischer
or Victor Grignard was not based on quantum physics (how could it be ?)
so the way we understand it nowadays is not the same that the way they
did !
Modern physics entered chemistry vehemently more than a century ago. It is
just that modern physics was not really understood until quantum theory
developed. Where would chemistry be without concepts of periodicity,
electrons, electromagnetic radiation, subnuclear particles, etc. What amazes
me is that there were chemists capable of developing their own theoretical
tools before the physics was understood.
Mendeleev, for example, was an astute observer and thinker. He had no clue
as to why the periodic table worked. Until the concepts of the Pauli
exclusion principle and atomic number were developed, deeper understanding
of the periodic table was not possible. Chemistry enabled further
explanation of subshells of transition elements and lanthanide elements.
Hund rules may help understand the weird way shells fill up. I do not know
if, even today with fancy computers, the order of filling of energy levels
can be determined analytically.
Bill
-- Ferme le Bush
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| User: "Mathias Rocher" |
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| Title: Re: Difference between Chemistry and Physics |
07 Apr 2006 04:39:55 AM |
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Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject? Can someone refer me
to sources which talk about this?
I don't have any sources to support this "historical" approach. All I
can say is that all of that is approximately correct. Chemistry and
physics are not two different approaches to the same subject, because
the range of subjects covered by physics is larger than only chemistry
: let's say that chemistry is nowadays a part of physics, just as
optics, thermodynamics, and mechanics are.
But in fact the two worlds of chemistry and physics are still
separated. There are a lot of reasons for this separation, some
scientific and practical (most of the problems that the chemists are
trying to resolve are of little interest on a physicist's point of
view), some historical (inheritence of the ancient time where chemists
and physicists were as foreigner to each other than geologists to
psychologists), some economical and political reasons too (not the same
fundings, not the same economical interests, not always the same
industry)...
And as you can see even sometimes by reading this forum, it makes that
sometimes chemists still react just as if chemistry was still a
completely different subject than physics ! And they are not totally
wrong.
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| User: "" |
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| Title: Re: Difference between Chemistry and Physics |
07 Apr 2006 11:37:22 AM |
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Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject? Can someone refer me
to sources which talk about this?
Not really. They were all (and more besides) lumped together as natural
or experimental philosophy in the dim and distant past. The oldest
universities still have degree titles like Natural Sciences Tripos.
Physics matured into a hard experimental science somewhat before
chemistry. Newton, the world's foremost theoretical physicist of his
day was also a pretty good alchemist too (the precursors of modern
chemistry were a lot more random recipes on a wing and a prayer in
those days).
Regards,
Martin Brown
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| User: "Gregory L. Hansen" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 10:31:57 AM |
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In article <1144087603.713637.111910@j33g2000cwa.googlegroups.com>,
cafeinst@msn.com <cafeinst@msn.com> wrote:
Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject? Can someone refer me
to sources which talk about this?
Thank you,
Craig
Chemistry, with roots in alchemy, concerns the properties and
transformations of matter. For a long time, all they could do was
mix things together, heat, and stir, and see what happens. It was largely
a cataloging of phenomena, perhaps with some pseudo-magical mutterings
thrown in.
Meanwhile, Newton and Galileo kicked off physics with studies of
mechanics and the motions of planets. That didn't particularly have a lot
to do with the nature and transformations of matter.
Thermodynamics, a pragmatic science which grew up during the industrial
revolution, has obvious applications in both fields, especially after it
was shown that heat is a form of energy. Physicists and chemists both
study essentially the same thermodynamics. And quantum mechanics finally
gave an understanding of atom-sized bodies, and physicists and chemists
learn the same theory although chemists immediately start applying
approximations appropriate to their many-body problems while physicists
linger on the fundamentals and two-body interactions.
Today there are nuclear chemists doing the work of physicists, condensed
matter physicists doing the work of chemists, and a lot of other overlap.
The biggest part of applied physics today is materials.
--
"Never argue with a fool. They will drag you down to their level and win
by experience."
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| User: "fkasner" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 03:30:41 PM |
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Gregory L. Hansen wrote:
In article <1144087603.713637.111910@j33g2000cwa.googlegroups.com>,
cafeinst@msn.com <cafeinst@msn.com> wrote:
Am I correct that the subjects of chemistry and physics were at one
time thought of as completely different subjects and that it was only
until recently, the 20th century, that they began to be thought of as
merely different approaches to the same subject? Can someone refer me
to sources which talk about this?
Thank you,
Craig
Chemistry, with roots in alchemy, concerns the properties and
transformations of matter. For a long time, all they could do was
mix things together, heat, and stir, and see what happens. It was largely
a cataloging of phenomena, perhaps with some pseudo-magical mutterings
thrown in.
Meanwhile, Newton and Galileo kicked off physics with studies of
mechanics and the motions of planets. That didn't particularly have a lot
to do with the nature and transformations of matter.
Thermodynamics, a pragmatic science which grew up during the industrial
revolution, has obvious applications in both fields, especially after it
was shown that heat is a form of energy. Physicists and chemists both
study essentially the same thermodynamics. And quantum mechanics finally
gave an understanding of atom-sized bodies, and physicists and chemists
learn the same theory although chemists immediately start applying
approximations appropriate to their many-body problems while physicists
linger on the fundamentals and two-body interactions.
Today there are nuclear chemists doing the work of physicists, condensed
matter physicists doing the work of chemists, and a lot of other overlap.
The biggest part of applied physics today is materials.
And for a long time there have been disciplines called physical
chemistry and chemical physics and people who get degrees in such areas.
Mine was in physical chemistry.
FK
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| User: "tadchem" |
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| Title: Re: Difference between Chemistry and Physics |
11 Apr 2006 05:22:40 PM |
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I was first a physical chemist and then became a chemical physicist.
I don't even know where I crossed the line.
Tom Davidson
Richmond, VA
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| User: "" |
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| Title: Re: Difference between Chemistry and Physics |
12 Apr 2006 04:13:59 AM |
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In article <1144794160.867637.125340@z34g2000cwc.googlegroups.com>,
"tadchem" <tadchem@comcast.net> wrote:
I was first a physical chemist and then became a chemical physicist.
I don't even know where I crossed the line.
Was it the day you picked up the Klein beaker by mistake?
/BAH
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| User: "Bob M" |
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| Title: Re: Difference between Chemistry and Physics |
10 Apr 2006 03:18:16 AM |
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Science is science.
The divisions between the sciences have no real basis they arbitrary
divisions placed in science by man for the convenience of study. The
more science you study the more insubstantial and less distinct the
divisions become.
You cannot divorce chemistry from physics, or biology from chemistry,
etc.
Bob Molony
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