Showing posts with label physics. Show all posts
Showing posts with label physics. Show all posts
Monday, January 4, 2010
Dark Energy and the Casimir Effect
It's a weird, weird universe, at the quantum level, with implications for the eventual fate of the universe....probably a Big Fizzle. Check out the APOD:http://antwrp.gsfc.nasa.gov/apod/ap100103.html
Tuesday, December 22, 2009
So just how does that 250 tonne 747 get off the ground?
And more importantly, how does it stay off the ground?
Great article on the basic principle behind fixed wing aircraft flight.
http://discovermagazine.com/2001/apr/featphysics/?searchterm=airplanes
Friday, December 18, 2009
Dark Matter: Encouraging results, but no smoking gun
Some possible events that might be dark matter interactions, but not statistically significant enough to warrant a definite yes. See the link below for a pdf summary from CDMS. http://cdms.berkeley.edu/results_summary.pdf
Tuesday, December 15, 2009
Dark matter news, maybe......
Something is happening, it seems, but no-one can tell for sure.....new techniques, or a major announcement? as Ted Bunn says, all eyes will be on ArXiv when the article is supposed to appear!
Ted Bunn's blog entry on the subject:
http://blog.richmond.edu/physicsbunn/2009/12/15/dark-matter-update/
Our sun in about 5 billion years
Our sun will go through this in about 5 billion years, we get a preview from Chi Cygni, a sun-like star about 550 light-years from Earth on its deathbed. Check out the link below for some really cool info on this.
http://www.cfa.harvard.edu/news/2009/pr200923.html
http://www.cfa.harvard.edu/news/2009/pr200923.html
Monday, December 14, 2009
WISE mission launches from Vandenberg AFB on time via Delta II rocket
The WISE (Wide Field Infrared Survey Explorer) mission lifted off today from Space Launch Complex 2 at Vandenberg AFB, California. It will study dark Near Earth Objects, nearby stars too cool to be seen in visible light and far-off galaxies. It will take images every 8-seconds and create a database of the entire sky as seen in infrared.
For more information: http://www.jpl.nasa.gov/wise/facts.cfm
For more information: http://www.jpl.nasa.gov/wise/facts.cfm
Thursday, December 10, 2009
Twinkle, twinkle little star........
....... how I wonder what you are.
That little line of verse summarises most of humanity's history in looking at the night sky. Just what are those little lights up there, anyway? Many theories were put forward, from holes in a cosmic animal skin covering the night sky allowing pinholes of daylight to peek through, to campfires of other peoples far, far away. Little wandering "stars" that appeared to change position regularly (planets, from the ancient Greek word for "moving") added to the confusion, as did stars that suddenly flared up and blazed brightly for a few days or weeks, and then fade out again. With mysteries of this kind, is it any wonder our ancestors tried to associate such appearances and behaviours with events on earth? Careful observation shows that the same patterns occur again and again every year at around about the same time. Why not see what happens each time, for example, the planet Mars is passing through the constellation Gemini? And thus was born the pseudoscience of astrology. It was comforting to know that we were linked with the sky, that we could have a semblance of control in an otherwise chaotic world.
But today, we know what the stars are. We know that constellations are temporary and that the planets and stars have no bearing on our lives, aside from inspiring us with awe at their beauty every time we look up.
So, what are the stars? Let me answer with another question. What is the closest star to Earth? (Hint: If you don't know, it's closer than you might think.) That's right. The sun. Our sun is a star. That implies that all stars are suns, however, not necessarily like ours.
All stars are suns.
Think about that for a moment. Every little star twinkling up there on a clear moonless night is a sun. Some are bigger, smaller, brighter and dimmer, than our sun, but are essentially similar. And now imagine that what we see is only the tiniest fraction of what's out there. It's estimated that there are up to 400 billion stars in our galaxy alone, and there are billions of galaxies. Isn't that amazing? How enormous is even just our galaxy?
Ok, so all stars are suns, but what are they exactly?
Essentially, they're big balls of plasma, no more, no less. And they have a life cycle, just like people do, but over a much vaster timescale. A star is born when enough hydrogen gas accumulates to ignite, a process called nuclear fusion. This is caused when the mass of hydrogen accumulation reaches a point where its gravity causes the internal pressure to fuse hydrogen atoms together to form helium nuclei, releasing huge amounts of energy in the process. This is what causes our sun, and all other stars, to shine. So the balancing act that is a star's life is between gravity, which makes it want to contract, and heat and outward pressure which make it want to expand. A successful star is one where these two forces are more or less equalised. And so it goes for millions of years in what we call the star's main sequence.
Eventually, though, the supply of hydrogen begins to run out and what happens then depends on the star's mass. It may begin to convert helium to carbon, or if it isn't massive enough, fusion reactions stop and the expansion pressure is enough to overcome the gravitational force and the star expands into a bloated red giant. Eventually it sheds it's outer region to leave a planetary nebula and a white dwarf star if it's between 0.08 and 5 times the suns mass, but over 5 it will explode in to one of the most violent events in the universe: a supernova.
When the helium is used up, the carbon gets fused into oxygen, magnesium, silicon and on until we hit iron. But wait, what's happening here? We know these substances from the periodic table of the elements. The star is building them, it's an element factory! That's right. Everything around you is built of star debris. But how did the iron on earth get here from the star's insides? Due to one of the most violent events in the universe, one that happens when the star starts to try "burning" iron. Iron removes most of the energy from the star, and gravity finally gets the upper hand. The iron core collapses in on itself, and the effect of this is like pulling the rug out from under the upper layers: they fall on the iron core and bounce back out, causing the star to explode in a supernova. Some are so bright, they can be seen in broad daylight for days, weeks or months before fading away again. All that remains is a neutron star formed by the supernova blast.
But, if the star is even bigger, more than 20 times the mass of our sun, it may end up as one of the most mysterious objects in the universe: a black hole.
But that's another story.
Twinkle twinkle little star, now I know just what you are..........
That little line of verse summarises most of humanity's history in looking at the night sky. Just what are those little lights up there, anyway? Many theories were put forward, from holes in a cosmic animal skin covering the night sky allowing pinholes of daylight to peek through, to campfires of other peoples far, far away. Little wandering "stars" that appeared to change position regularly (planets, from the ancient Greek word for "moving") added to the confusion, as did stars that suddenly flared up and blazed brightly for a few days or weeks, and then fade out again. With mysteries of this kind, is it any wonder our ancestors tried to associate such appearances and behaviours with events on earth? Careful observation shows that the same patterns occur again and again every year at around about the same time. Why not see what happens each time, for example, the planet Mars is passing through the constellation Gemini? And thus was born the pseudoscience of astrology. It was comforting to know that we were linked with the sky, that we could have a semblance of control in an otherwise chaotic world.
But today, we know what the stars are. We know that constellations are temporary and that the planets and stars have no bearing on our lives, aside from inspiring us with awe at their beauty every time we look up.
So, what are the stars? Let me answer with another question. What is the closest star to Earth? (Hint: If you don't know, it's closer than you might think.) That's right. The sun. Our sun is a star. That implies that all stars are suns, however, not necessarily like ours.
All stars are suns.
Think about that for a moment. Every little star twinkling up there on a clear moonless night is a sun. Some are bigger, smaller, brighter and dimmer, than our sun, but are essentially similar. And now imagine that what we see is only the tiniest fraction of what's out there. It's estimated that there are up to 400 billion stars in our galaxy alone, and there are billions of galaxies. Isn't that amazing? How enormous is even just our galaxy?
Ok, so all stars are suns, but what are they exactly?
Essentially, they're big balls of plasma, no more, no less. And they have a life cycle, just like people do, but over a much vaster timescale. A star is born when enough hydrogen gas accumulates to ignite, a process called nuclear fusion. This is caused when the mass of hydrogen accumulation reaches a point where its gravity causes the internal pressure to fuse hydrogen atoms together to form helium nuclei, releasing huge amounts of energy in the process. This is what causes our sun, and all other stars, to shine. So the balancing act that is a star's life is between gravity, which makes it want to contract, and heat and outward pressure which make it want to expand. A successful star is one where these two forces are more or less equalised. And so it goes for millions of years in what we call the star's main sequence.
Eventually, though, the supply of hydrogen begins to run out and what happens then depends on the star's mass. It may begin to convert helium to carbon, or if it isn't massive enough, fusion reactions stop and the expansion pressure is enough to overcome the gravitational force and the star expands into a bloated red giant. Eventually it sheds it's outer region to leave a planetary nebula and a white dwarf star if it's between 0.08 and 5 times the suns mass, but over 5 it will explode in to one of the most violent events in the universe: a supernova.
When the helium is used up, the carbon gets fused into oxygen, magnesium, silicon and on until we hit iron. But wait, what's happening here? We know these substances from the periodic table of the elements. The star is building them, it's an element factory! That's right. Everything around you is built of star debris. But how did the iron on earth get here from the star's insides? Due to one of the most violent events in the universe, one that happens when the star starts to try "burning" iron. Iron removes most of the energy from the star, and gravity finally gets the upper hand. The iron core collapses in on itself, and the effect of this is like pulling the rug out from under the upper layers: they fall on the iron core and bounce back out, causing the star to explode in a supernova. Some are so bright, they can be seen in broad daylight for days, weeks or months before fading away again. All that remains is a neutron star formed by the supernova blast.
But, if the star is even bigger, more than 20 times the mass of our sun, it may end up as one of the most mysterious objects in the universe: a black hole.
But that's another story.
Twinkle twinkle little star, now I know just what you are..........
Closing in on the Higgs Boson.
The Fermi National Accelerator Laboratory has made new discoveries that may help in discovering the Higgs Boson. See below for more details:
Hunt for Higgs
Hunt for Higgs
Wednesday, December 9, 2009
Forget the last post
Looks like it's going nowhere, for now. The blogosphere's rumourmill gota lot of people jumping the gun.....apparently no dark matter just yet.
http://blog.richmond.edu/physicsbunn/2009/12/09/mea-culpa/
http://blog.richmond.edu/physicsbunn/2009/12/09/mea-culpa/
Tuesday, December 8, 2009
Rumours that first dark matter particle found
Whoah. Let's see where this goes.
Rumours that first dark matter particle found - Short Sharp Science - New Scientist
Rumours that first dark matter particle found - Short Sharp Science - New Scientist
Concerning LHC's bird-bread power cut
It seems that it's not so sure that the bread-bird hypothesis is valid any more....another urban legend observed in the wild? Decide for yourself:
The truth about Birds and Baguettes
The truth about Birds and Baguettes
Sunday, December 6, 2009
LHC researchers publish first results....but no paradigm changing news just yet
First published results from LHC, but don't get too excited: The Higg's boson is a ways off yet.
http://tinyurl.com/yz63hmv
http://tinyurl.com/yz63hmv
Tuesday, December 1, 2009
LHC update: it’s now all-powerful | Bad Astronomy | Discover Magazine
Ooh! Ooh! More LHC! Grace à the Bad Astronomer!
LHC update: it’s now all-powerful | Bad Astronomy | Discover Magazine
LHC update: it’s now all-powerful | Bad Astronomy | Discover Magazine
Monday, November 30, 2009
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