A physics paper I wrote a couple of years ago. Thought it might be an interesting and informative read. The format is weird because I copied it from Microsoft Word and it's manually double-spaced.
David Presnall, Jr
The world of physics has long held a fascination for many people. Today,
modern technology and theory is bringing us an ever-increasing comprehension of
how our universe functions. The key to this is the understanding of the nature and
behavior of matter.
The first glimmer of the nanoworld came as early as 400 B.C. Many Greek
philosophers came to believe that all the matter in the earth was made of tiny,
indivisible particles called ‘atoms’ 1. The philosophy that included atoms was known
as atomism.
It was not until the Middle Ages that interest really grew in atomism, when
this largely discarded theory began to be resurrected by alchemists. Although some of
these scientists were merely trying to get rich by manipulating atoms 2, most were
sincerely interested in investigating the structure and behavior of these mysterious
particles. Without their research, we would not have the knowledge we do about
these tiny constituents of matter.
Several advances took place during the 18th and early19th centuries A.D. First,
an alchemist named Robert Boyle discovered some proof that atoms might exist. The
experiment used was the compression of air in a J-shaped tube and the observance of
its behavior. Second, Lavoisier demonstrated that no mass is gained or lost in a
chemical reaction. This is known as the Law of Mass Conservation. Third, Proust
discovered that elements which make up various substances always occur in whole
number ratios. This was compelling proof because atoms cannot be split into partial
atoms of the same element 3. Finally, Joseph Dalton designed the first periodic table of
elements.
The next major discoveries were the electron, proton, and neutron. For half of
the 19th century, scientists were puzzled by cathode rays, which emitted a glow in
cathode ray tubes (then known as Geissler tubes, although some refer to them as
Crookes tubes). In 1897, J.J. Thompson proposed that these were smaller pieces of
matter that are in atoms. After proving this hypothesis through multiple experiments,
he named them corpuscles, although the name was soon changed to electrons because
of the fact that these particles are used to conduct electricity. He also determined that
they had a negative charge. In 1903, Rutherford discovered that alpha rays, a type of
radiation, were composed of positively charged particles. In 1909, he found these
particles in atoms, named them protons, and established the belief that atoms have
nuclei, which contain most of their mass. In 1930, Frederic and Irene Joliot-Curie
discovered that they could knock neutral radiation out of atoms by bombarding them
with protons. After researching these particles extensively, they named the particles
neutrons, due to their lack of any electrical charge.
During the 1930s-1940s, particles were found in abundant types and numbers.
This period is often referred to as the particle explosion, and, in fact, particles at one
point were being discovered at the astounding rate of one every month. Probably the
most important particles discovered at this time were quarks. Protons, neutrons, and
some other particles are made from quarks. There are six types of quark: up, down,
strange, charm, top, and bottom. Protons are made of two up and one down quark,
while neutrons consist of two down and one up quark. Just a few of the other
particles are kaons, positrons, neutrinos, taus, muons, mesons, and the five force
carriers: photons, gluons, Z bosons, W bosons, and the theorized carrier of gravity,
the graviton.
Albert Einstein revolutionized the scientific community in the early 1900s
with his two theories. The first is called special relativity. This theory deals with
motion through space and time, which combine to form spacetime 4. According to
Einstein, everything is moving at light speed, regardless of apparent motion.
Something perceived to be ‘standing still’ is actually traveling through time at light
speed. This is known as the universal energy expenditure constant. As our speed of
motion through space increases, our speed of travel through time decreases
accordingly. However, at modern speeds, this effect is negligible (as a person driving a
car at 120 miles per hour notes that 30 seconds have gone by, a stationary observer
would notice that, relative to him, the driver had only traveled for
29.99999999999952 seconds.) Obviously, such tiny differences cannot be
measured by today’s equipment. Also, note the use of the word relative. Except for
light, nothing can measure its speed absolutely, but must calculate it relative to an
object he perceives as being stationary. Of course, due to the fact that both the
moving person and a nonmoving person perceive the other as moving, both would
claim to be stationary while the other moved, as long as there was no point of
reference (such as the earth’s surface) 5.
Einstein’s other theory, general relativity, was produced because of
inconsistencies between Newton’s theory and special relativity—namely, the
Newtonian idea of instantaneous transmission of the gravitational force. Einstein had
proved that nothing is faster than light, so there had to be some mistake in Newton’s
theory. According to general relativity, all matter warps the fabric of spacetime. The
degree of this warping is, of course dependant on the mass 6 of the object in question.
Everything in the field of this warping is affected, resulting in the felt force of gravity.
The transmission of this force is not instantaneous, but actually travels at light speed.
There is a significant amount of experimental evidence that this is, indeed, the case.
In the 1930s, a new theory about the nanoworld became predominant in the
scientific community. Quantum mechanics tells us that many macroscopic physical
laws are meaningless on a nanoscopic level. At this magnification, space, rather than
being smooth, is a boiling frenzy of particle motion. Particles are jumping about
wildly, and even time itself has no meaning. Something there can happen before it
happens or even while it is happening. At this level, the principle of quantum tunneling, by which subatomic particles can penetrate through ‘impenetrable’
barriers, applies. Another extremely important aspect of this theory is wave-particle
duality. All matter behaves both as a particle and as a wave. This has been proven by
an experiment known as the double-slit experiment, in which particles are fired
through a pair of slits. When one slit is open and the other is closed, the particles
behave as they (theoretically) should. When both slits are open, however, the
particles create an interference pattern that would be expected from a wave. Finally,
the uncertainty principle must not be left out. According to this law, the two related
properties of velocity and location of a particle cannot both be calculated to 100%
accuracy, but can only add their accuracies to a limit of 100%. In other words, if
location is known to within 85% accuracy, velocity cannot be known to more than
15% accuracy. Therefore, there is an important tradeoff between accuracy in the two
numbers.
For years, physicists have harbored an embarrassing secret: the two theories
used to determine the behavior of matter, general relativity and quantum mechanics,
are fundamentally incompatible. The principles of quantum mechanics apply well to
tiny objects, while the principles of general relativity accurately predict the behavior
of massive objects. However, when an object, such as a black hole, is both tiny and
massive, the equations for the theories must be combined. This sounds simple enough,
but there is one major problem: the answer always comes out as infinity. The
probability that something will happen can never exceed 100%; yet the combined
equations give us a probability of infinity percent! Fortunately, a theory has recently
appeared which resolves this conflict, but to properly understand it, we must first
cover a few underlying concepts.
Particles have a property called spin. Every particle has spin, but different
particles have different amounts of it. For example, a graviton particle
has a spin of 2. Electrons have a spin of 1/2. It turns out that force carrier particles
have a whole-number spin, while matter particles have a spin that includes a fraction.
According to a theory known as supersymmetry, all particles have a supersymmetric
partner with a spin of exactly ½ less than theirs. Unfortunately, they have never been
seen but this could be because they are too large or small to be detected by modern
day particle accelerators, and there is evidence that they are, indeed too large.
Most people think of the universe as three-, or, at most, four-dimensional
(three space dimensions and one time dimension). Modern-day scientists believe,
however that there are eleven dimensions (ten space and one time), with the
possibility of more time dimensions. The eleventh dimension affects the shape of
particles, while the six other nonconventional dimensions have been
demonstrated as being ‘curled up’ into what is known as a Calabi-Yau shape
(manifold), which is named after two mathematicians who researched these
structures. A Calabi-Yau shape exists at every point in the universe, and is very small,
having little direct effect on normal life. As an attempt to give an idea of what one of
these shapes might look like, I have included a 3-D diagram of a Calabi-Yau manifold.
Unfortunately, a three-dimensional drawing fails to fully capture six dimensions of space.
Figure 1: A Calabi-Yau manifold (Look it up on Google, unfortunately I can't put pictures in here from my hard drive)
What we have been building up to is known as superstring theory 7. According
to this theory, all matter in the universe is made of tiny strands of energy, called
strings. There are two types of string, loops (closed) and snippets (open). These strings
vibrate in various patterns, and, like the strings on a violin produce various sounds
with different vibrations, these strings produce diverse particles with different
vibrations. This is where there is evidence for supersymmetry, because there are
vibrations in superstring (or just string) theory which correspond to the partners of
the various particles currently known to exist. However, one must realize that these
loops and snippets are exceedingly small (0.000000000000000000000000000000001
cm long) and are, in fact, the smallest bits of matter in the universe (for a more
graphical illustration of their size, imagine that an atom was the size of the universe:
On this scale, a string would be about the size of a large tree.) This concept is very
important to the resolution of the conflict between quantum mechanics and general
relativity. Strings are the smallest particles of matter, but they cannot detect the
quantum undulations called for by quantum mechanics, because they are too large.
Therefore, these undulations do not exist! This resolves the conflict between quantum
mechanics and general relativity by simply ‘smoothing out’ the fabric of spacetime.
Many advances have been made since the Greeks originally began to follow
the philosophy of ‘atomism’, but we are still far from a perfect understanding of our
universe. However, modern researchers are constantly discovering new particles and
information regarding the behavior of those particles. In the future, perhaps we may
obtain a full understanding of spacetime and matter, and perhaps even a concise theory of everything.
Appendices
Appendix 1: Footnotes
1: A Greek word literally meaning ‘indivisible’.
2: This practice, unfortunately, gave a bad name to all alchemists, and few people know alchemy for what it really was, believing rather that it was a false science.
3: This is because the splitting of an atom results in two atoms of a different element from the original.
4: Spacetime is the combination of the space and time dimensions.
5: Assuming, of course, that speed remains constant for the ‘moving’ object: if the speed varied, the person in motion would sense motion.
6: Mass is the measurement of the amount of matter in an object, as opposed to its weight in a given gravitational field.
7: Called superstring because it incorporates supersymmetry.
Appendix 2: Further Reading
Green, Brian: The Elegant Universe, Copyright 2000 Vintage Books
Johnson, Rebecca L.: Atomic Structure, Copyright 2008 Twenty-First Century Books
Hope you enjoyed it!
David Presnall, Jr
The world of physics has long held a fascination for many people. Today,
modern technology and theory is bringing us an ever-increasing comprehension of
how our universe functions. The key to this is the understanding of the nature and
behavior of matter.
The first glimmer of the nanoworld came as early as 400 B.C. Many Greek
philosophers came to believe that all the matter in the earth was made of tiny,
indivisible particles called ‘atoms’ 1. The philosophy that included atoms was known
as atomism.
It was not until the Middle Ages that interest really grew in atomism, when
this largely discarded theory began to be resurrected by alchemists. Although some of
these scientists were merely trying to get rich by manipulating atoms 2, most were
sincerely interested in investigating the structure and behavior of these mysterious
particles. Without their research, we would not have the knowledge we do about
these tiny constituents of matter.
Several advances took place during the 18th and early19th centuries A.D. First,
an alchemist named Robert Boyle discovered some proof that atoms might exist. The
experiment used was the compression of air in a J-shaped tube and the observance of
its behavior. Second, Lavoisier demonstrated that no mass is gained or lost in a
chemical reaction. This is known as the Law of Mass Conservation. Third, Proust
discovered that elements which make up various substances always occur in whole
number ratios. This was compelling proof because atoms cannot be split into partial
atoms of the same element 3. Finally, Joseph Dalton designed the first periodic table of
elements.
The next major discoveries were the electron, proton, and neutron. For half of
the 19th century, scientists were puzzled by cathode rays, which emitted a glow in
cathode ray tubes (then known as Geissler tubes, although some refer to them as
Crookes tubes). In 1897, J.J. Thompson proposed that these were smaller pieces of
matter that are in atoms. After proving this hypothesis through multiple experiments,
he named them corpuscles, although the name was soon changed to electrons because
of the fact that these particles are used to conduct electricity. He also determined that
they had a negative charge. In 1903, Rutherford discovered that alpha rays, a type of
radiation, were composed of positively charged particles. In 1909, he found these
particles in atoms, named them protons, and established the belief that atoms have
nuclei, which contain most of their mass. In 1930, Frederic and Irene Joliot-Curie
discovered that they could knock neutral radiation out of atoms by bombarding them
with protons. After researching these particles extensively, they named the particles
neutrons, due to their lack of any electrical charge.
During the 1930s-1940s, particles were found in abundant types and numbers.
This period is often referred to as the particle explosion, and, in fact, particles at one
point were being discovered at the astounding rate of one every month. Probably the
most important particles discovered at this time were quarks. Protons, neutrons, and
some other particles are made from quarks. There are six types of quark: up, down,
strange, charm, top, and bottom. Protons are made of two up and one down quark,
while neutrons consist of two down and one up quark. Just a few of the other
particles are kaons, positrons, neutrinos, taus, muons, mesons, and the five force
carriers: photons, gluons, Z bosons, W bosons, and the theorized carrier of gravity,
the graviton.
Albert Einstein revolutionized the scientific community in the early 1900s
with his two theories. The first is called special relativity. This theory deals with
motion through space and time, which combine to form spacetime 4. According to
Einstein, everything is moving at light speed, regardless of apparent motion.
Something perceived to be ‘standing still’ is actually traveling through time at light
speed. This is known as the universal energy expenditure constant. As our speed of
motion through space increases, our speed of travel through time decreases
accordingly. However, at modern speeds, this effect is negligible (as a person driving a
car at 120 miles per hour notes that 30 seconds have gone by, a stationary observer
would notice that, relative to him, the driver had only traveled for
29.99999999999952 seconds.) Obviously, such tiny differences cannot be
measured by today’s equipment. Also, note the use of the word relative. Except for
light, nothing can measure its speed absolutely, but must calculate it relative to an
object he perceives as being stationary. Of course, due to the fact that both the
moving person and a nonmoving person perceive the other as moving, both would
claim to be stationary while the other moved, as long as there was no point of
reference (such as the earth’s surface) 5.
Einstein’s other theory, general relativity, was produced because of
inconsistencies between Newton’s theory and special relativity—namely, the
Newtonian idea of instantaneous transmission of the gravitational force. Einstein had
proved that nothing is faster than light, so there had to be some mistake in Newton’s
theory. According to general relativity, all matter warps the fabric of spacetime. The
degree of this warping is, of course dependant on the mass 6 of the object in question.
Everything in the field of this warping is affected, resulting in the felt force of gravity.
The transmission of this force is not instantaneous, but actually travels at light speed.
There is a significant amount of experimental evidence that this is, indeed, the case.
In the 1930s, a new theory about the nanoworld became predominant in the
scientific community. Quantum mechanics tells us that many macroscopic physical
laws are meaningless on a nanoscopic level. At this magnification, space, rather than
being smooth, is a boiling frenzy of particle motion. Particles are jumping about
wildly, and even time itself has no meaning. Something there can happen before it
happens or even while it is happening. At this level, the principle of quantum tunneling, by which subatomic particles can penetrate through ‘impenetrable’
barriers, applies. Another extremely important aspect of this theory is wave-particle
duality. All matter behaves both as a particle and as a wave. This has been proven by
an experiment known as the double-slit experiment, in which particles are fired
through a pair of slits. When one slit is open and the other is closed, the particles
behave as they (theoretically) should. When both slits are open, however, the
particles create an interference pattern that would be expected from a wave. Finally,
the uncertainty principle must not be left out. According to this law, the two related
properties of velocity and location of a particle cannot both be calculated to 100%
accuracy, but can only add their accuracies to a limit of 100%. In other words, if
location is known to within 85% accuracy, velocity cannot be known to more than
15% accuracy. Therefore, there is an important tradeoff between accuracy in the two
numbers.
For years, physicists have harbored an embarrassing secret: the two theories
used to determine the behavior of matter, general relativity and quantum mechanics,
are fundamentally incompatible. The principles of quantum mechanics apply well to
tiny objects, while the principles of general relativity accurately predict the behavior
of massive objects. However, when an object, such as a black hole, is both tiny and
massive, the equations for the theories must be combined. This sounds simple enough,
but there is one major problem: the answer always comes out as infinity. The
probability that something will happen can never exceed 100%; yet the combined
equations give us a probability of infinity percent! Fortunately, a theory has recently
appeared which resolves this conflict, but to properly understand it, we must first
cover a few underlying concepts.
Particles have a property called spin. Every particle has spin, but different
particles have different amounts of it. For example, a graviton particle
has a spin of 2. Electrons have a spin of 1/2. It turns out that force carrier particles
have a whole-number spin, while matter particles have a spin that includes a fraction.
According to a theory known as supersymmetry, all particles have a supersymmetric
partner with a spin of exactly ½ less than theirs. Unfortunately, they have never been
seen but this could be because they are too large or small to be detected by modern
day particle accelerators, and there is evidence that they are, indeed too large.
Most people think of the universe as three-, or, at most, four-dimensional
(three space dimensions and one time dimension). Modern-day scientists believe,
however that there are eleven dimensions (ten space and one time), with the
possibility of more time dimensions. The eleventh dimension affects the shape of
particles, while the six other nonconventional dimensions have been
demonstrated as being ‘curled up’ into what is known as a Calabi-Yau shape
(manifold), which is named after two mathematicians who researched these
structures. A Calabi-Yau shape exists at every point in the universe, and is very small,
having little direct effect on normal life. As an attempt to give an idea of what one of
these shapes might look like, I have included a 3-D diagram of a Calabi-Yau manifold.
Unfortunately, a three-dimensional drawing fails to fully capture six dimensions of space.
Figure 1: A Calabi-Yau manifold (Look it up on Google, unfortunately I can't put pictures in here from my hard drive)
What we have been building up to is known as superstring theory 7. According
to this theory, all matter in the universe is made of tiny strands of energy, called
strings. There are two types of string, loops (closed) and snippets (open). These strings
vibrate in various patterns, and, like the strings on a violin produce various sounds
with different vibrations, these strings produce diverse particles with different
vibrations. This is where there is evidence for supersymmetry, because there are
vibrations in superstring (or just string) theory which correspond to the partners of
the various particles currently known to exist. However, one must realize that these
loops and snippets are exceedingly small (0.000000000000000000000000000000001
cm long) and are, in fact, the smallest bits of matter in the universe (for a more
graphical illustration of their size, imagine that an atom was the size of the universe:
On this scale, a string would be about the size of a large tree.) This concept is very
important to the resolution of the conflict between quantum mechanics and general
relativity. Strings are the smallest particles of matter, but they cannot detect the
quantum undulations called for by quantum mechanics, because they are too large.
Therefore, these undulations do not exist! This resolves the conflict between quantum
mechanics and general relativity by simply ‘smoothing out’ the fabric of spacetime.
Many advances have been made since the Greeks originally began to follow
the philosophy of ‘atomism’, but we are still far from a perfect understanding of our
universe. However, modern researchers are constantly discovering new particles and
information regarding the behavior of those particles. In the future, perhaps we may
obtain a full understanding of spacetime and matter, and perhaps even a concise theory of everything.
Appendices
Appendix 1: Footnotes
1: A Greek word literally meaning ‘indivisible’.
2: This practice, unfortunately, gave a bad name to all alchemists, and few people know alchemy for what it really was, believing rather that it was a false science.
3: This is because the splitting of an atom results in two atoms of a different element from the original.
4: Spacetime is the combination of the space and time dimensions.
5: Assuming, of course, that speed remains constant for the ‘moving’ object: if the speed varied, the person in motion would sense motion.
6: Mass is the measurement of the amount of matter in an object, as opposed to its weight in a given gravitational field.
7: Called superstring because it incorporates supersymmetry.
Appendix 2: Further Reading
Green, Brian: The Elegant Universe, Copyright 2000 Vintage Books
Johnson, Rebecca L.: Atomic Structure, Copyright 2008 Twenty-First Century Books
Hope you enjoyed it!
