[1305.5495] On the Importance of Conceptual Thinking Outside the Simulation Box:
"Any ambitious construction project requires architects for its design and engineers who apply the design to the real world. As scientific research shifts towards large groups which focus on the engineering aspects of linking data to existing models, architectural skills are becoming rare among young theorists. Senior researchers should mentor qualified students and postdocs to think creatively about the big picture without unwarranted loyalty to ancient blueprints from past generations of architects."
'via Blog this'
Friday, May 24, 2013
Thursday, May 23, 2013
Wednesday, May 22, 2013
Mesoamerican architecture - Wikipedia, the free encyclopedia
Mesoamerican architecture - Wikipedia, the free encyclopedia:
"Mesoamerican architecture is the set of architectural traditions produced by pre-Columbian cultures and civilizations of Mesoamerica, traditions which are best known in the form of public, ceremonial and urban monumental buildings and structures. The distinctive features of Mesoamerican architecture encompass a number of different regional and historical styles, which however are significantly interrelated. These styles developed throughout the different phases of Mesoamerican history as a result of the intensive cultural exchange between the different cultures of the Mesoamerican culture area through thousands of years. Mesoamerican architecture is mostly noted for its pyramids which are the largest such structures (outside of Ancient Egypt and the Chola Empire)."
'via Blog this'
"Mesoamerican architecture is the set of architectural traditions produced by pre-Columbian cultures and civilizations of Mesoamerica, traditions which are best known in the form of public, ceremonial and urban monumental buildings and structures. The distinctive features of Mesoamerican architecture encompass a number of different regional and historical styles, which however are significantly interrelated. These styles developed throughout the different phases of Mesoamerican history as a result of the intensive cultural exchange between the different cultures of the Mesoamerican culture area through thousands of years. Mesoamerican architecture is mostly noted for its pyramids which are the largest such structures (outside of Ancient Egypt and the Chola Empire)."
'via Blog this'
Tuesday, May 21, 2013
See Mercury, Venus and Jupiter in Tightest Night Sky Cluster until 2026 | Observations, Scientific American Blog Network
See Mercury, Venus and Jupiter in Tightest Night Sky Cluster until 2026 | Observations, Scientific American Blog Network:
"Cicadas aren’t the only scientific rarity expected this month. At the end of May three planets will be visible to the naked eye in one small area of the sky. The planets Mercury, Venus and Jupiter will form “the tightest gathering of three naked-eye planets that the world will see until 2026,” according to the venerable Sky & Telescope magazine."
'via Blog this'
"Cicadas aren’t the only scientific rarity expected this month. At the end of May three planets will be visible to the naked eye in one small area of the sky. The planets Mercury, Venus and Jupiter will form “the tightest gathering of three naked-eye planets that the world will see until 2026,” according to the venerable Sky & Telescope magazine."
'via Blog this'
Yitang Zhang Proves 'Landmark' Theorem in Distribution of Prime Numbers | Simons Foundation
Yitang Zhang Proves 'Landmark' Theorem in Distribution of Prime Numbers | Simons Foundation:
"On April 17, a paper arrived in the inbox of Annals of Mathematics, one of the discipline’s preeminent journals. Written by a mathematician virtually unknown to the experts in his field — a 50-something lecturer at the University of New Hampshire named Yitang Zhang — the paper claimed to have taken a huge step forward in understanding one of mathematics’ oldest problems, the twin primes conjecture."
'via Blog this'
"On April 17, a paper arrived in the inbox of Annals of Mathematics, one of the discipline’s preeminent journals. Written by a mathematician virtually unknown to the experts in his field — a 50-something lecturer at the University of New Hampshire named Yitang Zhang — the paper claimed to have taken a huge step forward in understanding one of mathematics’ oldest problems, the twin primes conjecture."
'via Blog this'
An Unheralded Breakthrough: The Rosetta Stone of Mathematics | Guest Blog, Scientific American Blog Network
An Unheralded Breakthrough: The Rosetta Stone of Mathematics | Guest Blog, Scientific American Blog Network:
"There is no Nobel Prize in mathematics, but in 2001 the Norwegian government established a million-dollar Abel Prize, which is widely considered as an equivalent of the Nobel for mathematicians. This year’s prize was awarded to Pierre Deligne, professor emeritus at the Institute for Advanced Study in Princeton, N.J. Today, he is honored at a ceremony held in Oslo."
'via Blog this'
"There is no Nobel Prize in mathematics, but in 2001 the Norwegian government established a million-dollar Abel Prize, which is widely considered as an equivalent of the Nobel for mathematicians. This year’s prize was awarded to Pierre Deligne, professor emeritus at the Institute for Advanced Study in Princeton, N.J. Today, he is honored at a ceremony held in Oslo."
'via Blog this'
Survivors Pulled from Oklahoma Tornado Debris: Scientific American
Survivors Pulled from Oklahoma Tornado Debris: Scientific American:
"Emergency workers pulled more than 100 survivors from the rubble of homes, schools and a hospital in an Oklahoma town hit by a powerful tornado, and officials lowered the death toll from the storm to 24, including nine children."
'via Blog this'
"Emergency workers pulled more than 100 survivors from the rubble of homes, schools and a hospital in an Oklahoma town hit by a powerful tornado, and officials lowered the death toll from the storm to 24, including nine children."
'via Blog this'
[1305.4208] Relation between masses of particles and the Fermi constant in the electroweak Standard Model
[1305.4208] Relation between masses of particles and the Fermi constant in the electroweak Standard Model:
"An empirical formula relating the physical masses of elementary particles and the Fermi constant is proposed. Although no mechanism or theoretical model behind this formula is advocated, we seek for a possible physical interpretation. If not a simple numerical coincidence, this formula may motivate theorists to search for relations among the different sectors of the Electroweak Standard model."
'via Blog this'
"An empirical formula relating the physical masses of elementary particles and the Fermi constant is proposed. Although no mechanism or theoretical model behind this formula is advocated, we seek for a possible physical interpretation. If not a simple numerical coincidence, this formula may motivate theorists to search for relations among the different sectors of the Electroweak Standard model."
'via Blog this'
Sunday, May 19, 2013
Antarctic Neutrino Observatory Detects Unexplained High-Energy Particles: Scientific American
Antarctic Neutrino Observatory Detects Unexplained High-Energy Particles: Scientific American:
"A preliminary analysis from the IceCube detector reveals more than two dozen neutrinos of unknown origin"
'via Blog this'
"A preliminary analysis from the IceCube detector reveals more than two dozen neutrinos of unknown origin"
'via Blog this'
6 Women Scientists Who Were Snubbed Due to Sexism
6 Women Scientists Who Were Snubbed Due to Sexism:
"Despite enormous progress in recent decades, women still have to deal with biases against them in the sciences."
'via Blog this'
"Despite enormous progress in recent decades, women still have to deal with biases against them in the sciences."
'via Blog this'
Saturday, May 18, 2013
Hipparchus - Wikipedia, the free encyclopedia
Hipparchus - Wikipedia, the free encyclopedia:
"Hipparchus /hɪˈpɑːrkəs/ of Nicaea, or more correctly Hipparchos (Greek: Ἵππαρχος, Hipparkhos; c. 190 BC – c. 120 BC), was a Greek astronomer, geographer, and mathematician of the Hellenistic period. He is considered the founder of trigonometry[1] but is most famous for his incidental discovery of precession of the equinoxes.[2]"
'via Blog this'
"Hipparchus /hɪˈpɑːrkəs/ of Nicaea, or more correctly Hipparchos (Greek: Ἵππαρχος, Hipparkhos; c. 190 BC – c. 120 BC), was a Greek astronomer, geographer, and mathematician of the Hellenistic period. He is considered the founder of trigonometry[1] but is most famous for his incidental discovery of precession of the equinoxes.[2]"
'via Blog this'
Axial precession - Wikipedia, the free encyclopedia
Axial precession - Wikipedia, the free encyclopedia:
"In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In particular, it refers to the gradual shift in the orientation of Earth's axis of rotation, which, similar to a wobbling top, traces out a pair of cones joined at their apices in a cycle of approximately 26,000 years [1] (called a Great or Platonic Year in astrology). The term "precession" typically refers only to this largest secular motion; other changes in the alignment of Earth's axis – nutation and polar motion – are much smaller in magnitude."
'via Blog this'
"In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In particular, it refers to the gradual shift in the orientation of Earth's axis of rotation, which, similar to a wobbling top, traces out a pair of cones joined at their apices in a cycle of approximately 26,000 years [1] (called a Great or Platonic Year in astrology). The term "precession" typically refers only to this largest secular motion; other changes in the alignment of Earth's axis – nutation and polar motion – are much smaller in magnitude."
'via Blog this'
Flag of Brazil - Wikipedia, the free encyclopedia
Flag of Brazil - Wikipedia, the free encyclopedia:
"A list of constellations and stars on the map:
1. Procyon (α Canis Minoris),
2. Canis Major, with the largest star depicting Sirius,
3. Canopus (α Carinae),
4. Spica (α Virginis)
5. Hydra
6. Crux Australis
7. Sigma Octantis (σ Octantis; south pole star)
8. Triangulum Australe
9. Scorpius, with the largest star depicting Antares
"
'via Blog this'
"A list of constellations and stars on the map:
1. Procyon (α Canis Minoris),
2. Canis Major, with the largest star depicting Sirius,
3. Canopus (α Carinae),
4. Spica (α Virginis)
5. Hydra
6. Crux Australis
7. Sigma Octantis (σ Octantis; south pole star)
8. Triangulum Australe
9. Scorpius, with the largest star depicting Antares
'via Blog this'
Alpha Crucis - Wikipedia, the free encyclopedia
Alpha Crucis - Wikipedia, the free encyclopedia:
"Alpha Crucis (α Cru, α Crucis, also Acrux, HD 108248) is the brightest star in the constellation Crux, the Southern Cross, and, at a combined visual magnitude 0.77,[6] is the twelfth brightest star[6] in the night sky. Acrux is the southernmost first-magnitude star,[6] just a bit more southerly than Alpha Centauri."
'via Blog this'
"Alpha Crucis (α Cru, α Crucis, also Acrux, HD 108248) is the brightest star in the constellation Crux, the Southern Cross, and, at a combined visual magnitude 0.77,[6] is the twelfth brightest star[6] in the night sky. Acrux is the southernmost first-magnitude star,[6] just a bit more southerly than Alpha Centauri."
'via Blog this'
[physics/0407108] On the possible discovery of precessional effects in ancient astronomy
[physics/0407108] On the possible discovery of precessional effects in ancient astronomy:
"The possible discovery of astronomical effects due to precession - such as the shift in the declination of heliacal raising of bright stars or the precession of the equinoxes - is reviewed for various ancient cultures in the world. Although definitive evidence of the discovery is still lacking, the quantity of hints (for instance, coming from ancient Egypt) is impressive and stimulating in view of further research."
"The earth rotates around its axis in 24 hours, and the earth’s axis rotates around the axis orthogonal to the ecliptic, describing a cone. Thus, the motion of the earth is similar to that of a top: the earth precedes. The period of this movement is extremely long with respect to human life, since the axis completes a cycle in 25776 years.
Precession has a very important consequence on long-term naked eye astronomy. First of all, the prolongation of the earth axis on the celestial sphere defines astronomical north. The direction in which astronomical north points – possibly indicating a star, thereby a pole star – changes therefore continuously in time. Today’s pole star (our Polaris) will resign to be the pole star in a few centuries, and all the stars which lie close to the circle described by the pole (actually not exactly a closed circle, due to perturbations) will become “pole stars” one time each precessional cycle. For instance, in Palaeolithic times, the north pole crossed the Milky Way and the Pole star in 15000 BC was Delta-Cygnus. The north-pole sky was therefore completely different from ours; it was probably depicted in a fresco of the famous Lascaux grotto (Rappenglueck 1998)."
'via Blog this'
"The possible discovery of astronomical effects due to precession - such as the shift in the declination of heliacal raising of bright stars or the precession of the equinoxes - is reviewed for various ancient cultures in the world. Although definitive evidence of the discovery is still lacking, the quantity of hints (for instance, coming from ancient Egypt) is impressive and stimulating in view of further research."
"The earth rotates around its axis in 24 hours, and the earth’s axis rotates around the axis orthogonal to the ecliptic, describing a cone. Thus, the motion of the earth is similar to that of a top: the earth precedes. The period of this movement is extremely long with respect to human life, since the axis completes a cycle in 25776 years.
Precession has a very important consequence on long-term naked eye astronomy. First of all, the prolongation of the earth axis on the celestial sphere defines astronomical north. The direction in which astronomical north points – possibly indicating a star, thereby a pole star – changes therefore continuously in time. Today’s pole star (our Polaris) will resign to be the pole star in a few centuries, and all the stars which lie close to the circle described by the pole (actually not exactly a closed circle, due to perturbations) will become “pole stars” one time each precessional cycle. For instance, in Palaeolithic times, the north pole crossed the Milky Way and the Pole star in 15000 BC was Delta-Cygnus. The north-pole sky was therefore completely different from ours; it was probably depicted in a fresco of the famous Lascaux grotto (Rappenglueck 1998)."
'via Blog this'
Giulio Magli - Wikipedia, the free encyclopedia
Giulio Magli - Wikipedia, the free encyclopedia:
"Giulio Magli is an Italian Astrophysicist/Archaeoastronomer working primarily on the relationship between the architecture of ancient cultures and the sky."
'via Blog this'
"Giulio Magli is an Italian Astrophysicist/Archaeoastronomer working primarily on the relationship between the architecture of ancient cultures and the sky."
'via Blog this'
Friday, May 17, 2013
Amber Reed's Quiz
Chapter 16: Dark matter, dark energy and the fate of universe
16.1:unseen influences in the cosmos
what do we mean by dark matter and dark energy?
Content of Universe:
dark matter: an undetected for of mass that emits little or no light
but whose existence we infer from its gravitational influence
dark energy: an unknown form of energy that seems to be the source of a repulsive force causing the expansion of the universe to accelerate
normal matter ~4.6%
normal matter inside stars ~.7%
normal matter outside stars~3.9%
dark matter~23%
dark energy ~72%
16.2 evidence for dark matter
what is the evidence for dark matter in galaxies?
we measure the mass of the solar system using the orbits of planets
orbital period
average distance
or for circles:
orbital velocity
orbital radius
rotation curve: a plot of orbital speed versus orbital radius
solar system's rotation curve declines because Sun has almost all the mass
the rotation curve of the Milky Way stays flat with distance
mass must be more spread out than in the solar system
the mass in the Milky Way is spread out over a larger region than the stars
most of the Milky Way's mass seems to be dark matter!
the visible portion of a galaxy lies deep in the heat of a large halo of dark matter
we can measure orbital velocities in other spiral galaxies using the Doppler shift of the 21-cm line of atomic H
the broadening of spectral lines in elliptical galaxies tells us how fast the stars are orbiting
theses galaxies also have dark matter
what is the evidence for dark matter in clusters of galaxies?
the mass we find from galaxy motions in a cluster is about 50 times larger than the ass in stars!
clusters contain large amounts of X-rays -emitting hot gas
the temperature of gas (particle motions) tells us cluster mass:
85% dark matter
13% hot gas
2%stars
gravitational lensing, the bending of light rays by gravity,can also tell us a cluster's mass
a gravitational lens distorts our view of things behind it
all three methods of measuring cluster ass indicate similar amounts of dark matter
does dark matter rely exist?
dark matter really exists and we are observing the effects of its gravitational attraction
something is wrong with out understanding of gravity, causing us to mistakenly infer the existence
what might dark matter be made of?
ordinary matter(MACHOs)
massive compact Halo Objects: dead r failed stars in halos of galaxies
exotic particles(WIMPs)
weakly interacting massive particles:mysterious neutrino-like particles
compact starlike objects occasionally make other stars appear brighter through lensing...
Why WIMPs?
theres not enough ordinary matter
WIMPs could be leftover from the Big Bang
Models involving WIMPs explain how galaxy formation works
16.3 structure formation
what is the role of dark matter in galaxy formation?
gravity of dark matter is what caused protogalactic clouds to contract early in time
WIMPs can contract to the center because they don't radiate away their orbital energy
dark matter is still pulling things together
after correcting fro Hubble's law, we can see that galaxies are flowing toward the densest regions of space
what are the largest structures in the universe?
maps of galaxy positions reveal extremely large structures:superclusters and voids
models show that the gravity of dark matter pulls mass into denser regions-the universe grows lumpier with time
structures in galaxy maps look very similar to the ones found in models in which dark matter is WIMPs
16.4 the fate of the universe
Will the universe continue expanding forever?
fate of universe depends on the amount of dark matter
amount of matter is ~25% of the critical density, suggesting fate is eternal expansion
but expansion appears to be speeding up! (dark energy??)
estimated age depends on both dark matter and dark energy
Is the expansion of the universe accelerating?
the brightness of distant white dwarf supernovae tells us how much the universe has expanded since they exploded
an accelerating universe is the best fit to supernova data
16.1:unseen influences in the cosmos
what do we mean by dark matter and dark energy?
Content of Universe:
dark matter: an undetected for of mass that emits little or no light
but whose existence we infer from its gravitational influence
dark energy: an unknown form of energy that seems to be the source of a repulsive force causing the expansion of the universe to accelerate
normal matter ~4.6%
normal matter inside stars ~.7%
normal matter outside stars~3.9%
dark matter~23%
dark energy ~72%
16.2 evidence for dark matter
what is the evidence for dark matter in galaxies?
we measure the mass of the solar system using the orbits of planets
orbital period
average distance
or for circles:
orbital velocity
orbital radius
rotation curve: a plot of orbital speed versus orbital radius
solar system's rotation curve declines because Sun has almost all the mass
the rotation curve of the Milky Way stays flat with distance
mass must be more spread out than in the solar system
the mass in the Milky Way is spread out over a larger region than the stars
most of the Milky Way's mass seems to be dark matter!
the visible portion of a galaxy lies deep in the heat of a large halo of dark matter
we can measure orbital velocities in other spiral galaxies using the Doppler shift of the 21-cm line of atomic H
the broadening of spectral lines in elliptical galaxies tells us how fast the stars are orbiting
theses galaxies also have dark matter
what is the evidence for dark matter in clusters of galaxies?
the mass we find from galaxy motions in a cluster is about 50 times larger than the ass in stars!
clusters contain large amounts of X-rays -emitting hot gas
the temperature of gas (particle motions) tells us cluster mass:
85% dark matter
13% hot gas
2%stars
gravitational lensing, the bending of light rays by gravity,can also tell us a cluster's mass
a gravitational lens distorts our view of things behind it
all three methods of measuring cluster ass indicate similar amounts of dark matter
does dark matter rely exist?
dark matter really exists and we are observing the effects of its gravitational attraction
something is wrong with out understanding of gravity, causing us to mistakenly infer the existence
what might dark matter be made of?
ordinary matter(MACHOs)
massive compact Halo Objects: dead r failed stars in halos of galaxies
exotic particles(WIMPs)
weakly interacting massive particles:mysterious neutrino-like particles
compact starlike objects occasionally make other stars appear brighter through lensing...
Why WIMPs?
theres not enough ordinary matter
WIMPs could be leftover from the Big Bang
Models involving WIMPs explain how galaxy formation works
16.3 structure formation
what is the role of dark matter in galaxy formation?
gravity of dark matter is what caused protogalactic clouds to contract early in time
WIMPs can contract to the center because they don't radiate away their orbital energy
dark matter is still pulling things together
after correcting fro Hubble's law, we can see that galaxies are flowing toward the densest regions of space
what are the largest structures in the universe?
maps of galaxy positions reveal extremely large structures:superclusters and voids
models show that the gravity of dark matter pulls mass into denser regions-the universe grows lumpier with time
structures in galaxy maps look very similar to the ones found in models in which dark matter is WIMPs
16.4 the fate of the universe
Will the universe continue expanding forever?
fate of universe depends on the amount of dark matter
amount of matter is ~25% of the critical density, suggesting fate is eternal expansion
but expansion appears to be speeding up! (dark energy??)
estimated age depends on both dark matter and dark energy
Is the expansion of the universe accelerating?
the brightness of distant white dwarf supernovae tells us how much the universe has expanded since they exploded
an accelerating universe is the best fit to supernova data
Chelsea Esposito's Quiz
1. What do we mean by dark matter and dark energy?
Dark Matter is an undetected form of mass that emits little or no light but whose existence we infer from
its gravitational influence. Dark Energy is an unknown form of energy that seems to be the source of a
repulsive force causing the expansion of the universe to accelerate.
2. What is the evidence for dark matter in galaxies?
Rotation curves of galaxies are flat, indicating that most of their matter lies outside their visible regions.
3. What is the evidence for dark matter in clusters of galaxies?
Masses measured from galaxy motions, temperature of hot gas, and gravitational lensing all indicate that
the vast majority of matter in clusters is dark.
4. Does dark matter really exist?
Yes. Either dark matter exists or our understanding of our gravity must be revised.
5. What might dark matter be made of?
There does not seem to be enough normal (baryonic) matter to account for all the dark matter, so most
astronomers suspect that dark matter is made of (non-baryonic) particles that have not yet been discovered.
6. What is the role of dark matter in galaxy formation?
The gravity of dark matter seems to be what drew gas together into protogalactic clouds, initiating the
process of galaxy formation.
7. What are the largest structures in the universe?
Galaxies appear to be distributed in gigantic chains and sheets that surround great voids.
8. Will the universe continue expanding forever?
Current measurements indicate that there is not enough dark matter to prevent the universe from expanding
forever.
9. Is the expansion of the universe accelerating?
An accelerating universe is the best explanation for the distances we measure when using white dwarf
supernovae as standard candles.
10. Who discovered this acceleration?
Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess for the 1998 discovery of the accelerating expansion
of the Universe through observations of distant supernovae.
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