The Fabric of Space-time
Image: What happens to light as it passes through a point of space-time in where mass has been applied, as well as why objects in space orbit the way they do (planets, galaxies, clusters, etc.)
Also known as the Space-time Continuum, I’ve always been fascinated about the very space that holds the planet we live on, stars we see at night, solar system we observe, and supernovas we stargaze on telescopes. In astronomy you hear the term space-time get used a lot and I thought I’d highlight key features that describe what this fabric is. I find it odd that not that many people stop to think what holds us up, how are we suspended in space-time? Well, technically we’re not suspended. We’re constantly moving, constantly orbiting. And it’s not just Earth and the solar system joining in on this cosmic dance, you can include star clusters, galaxies, super clusters and even Blackholes, just about everything in our Universe. Keep in mind that even as you read this post, our solar system is orbiting the Milky Way galaxy, traveling at roughly 220 kilometers a second!
What is Space-time?
Einstein visualized gravity as a manifestation of the curvature of space-time - the three space dimensions and a fourth time dimension. Most of us cannot visualize a curvature of four dimensional space-time, so visualize a curved two dimensional rubber sheet. Placing a mass on the rubber sheet curves it downward like space-time curves in the presence of a mass. On such a rubber sheet a small mass can circle around the curvature produced by a large mass, just as planets orbit the Sun. Or a mass can roll straight downward just as an object falls to the Earth. Space-time being the very “material” these events and masses take place on.
Einstein explained gravity as a result of the curvature of space-time near the presence of a mass. The differences between general relativity and Newton’s law of gravity only become noticeable when the gravitational force is very strong.
Einstein’s general theory of relativity is one of the crowning intellectual achievements of the 20th century and led to such predictions as black holes, gravitational lenses, and the expanding universe. So far it has passed every experimental test with flying colors.
Info via Suite101
Pulsars
Ever look up at a clear night sky and notice some of the stars blink a bit more than others? They dwindle and fade in and out at different rates, almost making the skies look like sparkling water. What you are looking at most of the time is actual stars that are making their way to the end of their life. The moment prior to their eventual death
But to understand what a Pulsar is you need to Understand what Neutron stars are as well. Neutron stars are one of the possible ends for a star. They result from massive stars which have mass greater than 4 to 8 times that of our Sun. After these stars have finished burning their nuclear fuel, they undergo a supernova explosion. This explosion blows off the outer layers of a star into a beautiful supernova remnant. The central region of the star collapses under gravity. It collapses so much that protons and electrons combine to form neutrons. Hence the name “neutron star”.
Simply put, pulsars are rotating neutron stars. And pulsars appear to pulse because they rotate, Like shown in the figures below & above.
Pulsars are spinning neutron stars that have jets of particles moving almost at the speed of light streaming out above their magnetic poles. These jets produce very powerful beams of light. In addition, since stars variate in energy output, every single pulsar in the night sky is unique and has it’s own “pulsating” beacon. Kind of the same way species here on Earth have variations of the beating heart.
Information Via: NASA
(Source: ikenbot)
Meet Dave. He is made of things, as are you and I
Our bodies are comprised of a vast array of elements, with oxygen, carbon, hydrogen, and nitrogen remaining the most abundant. But there are many other chemical elements present, all contributing to our health and longevity. The nifty figure above lists each element that has been isolated from the human body in the order of decreasing mass.
This chart is based on the work of Ed Uthman, who derived the data from The Elements, by John Emsley.
(via Starts With a Bang)
Why We Dream: Real Reasons Revealed
The slumbering mind might not seem like an apt tool for any critical thinking, but humans can actually solve problems while asleep, researchers say. Not only that, but one purpose for dreaming itself may be to help us find solutions to puzzles that plague us during waking hours.
Dreams are highly visual and often illogical in nature, which makes them ripe for the type of “out-of-the-box” thinking that some problem-solving requires, said Deirdre Barrett, a psychologist at Harvard University.
Barrett’s theory on dreaming, which she discussed at the Association for Psychological Science meeting here last month, boils down to this: Dreaming is really just thinking, but in a slightly different state from when our eyes are open.
“Whatever the state we’re put in, we’re still working on the same problems,” Barrett said. Although dreams might have initially evolved for a different purpose, they likely have been refined over time so they can serve double-duty: help the brain reboot itself and problem-solve.
Dreams and evolution
A theory to explain dreams, or any human behavior for that matter, needs to take into account evolution, Barrett said. But many early theories of dreaming either didn’t address evolution at all, or downright contradicted it, she said.
For instance, Sigmund Freud proposed dreams exist to fulfill our wishes. But such gratification in an imaginary world would do little to help us adapt our instincts to the physical world, which is one key point of evolution, Barrett said.
Others have proposed dreams are more of a side effect of the sleep cycle. Dreams usually occur during Rapid Eye Movement, or REM, sleep. This stage is thought to serve several functions: to rest a part of the brain (since some areas are active while others aren’t) and to replenish brain chemicals, such as neurotransmitters.
This has led some to say that dreams happen simply because REM sleep happens, Barrett said. The psychologist Steven Pinker once likened dreams to computer screen savers, saying that it perhaps “doesn’t really matter what the content is as long as certain parts of the brain are active.”
However, Barrett disagrees. “My opinion is that, evolution just isn’t wasteful, that when things evolve for one purpose, that generally they don’t continue throughout time to have only that purpose, but anything else that may be useful about them gets refined,” she said in a telephone interview with LiveScience prior to the convention.
She also noted that REM sleep has been around for quite some time, since mammals evolved some 220 million years ago. “The longer something has existed during evolutionary history, the likelier it is to have other functions overlaid on it,” she said at the convention.
Problem-solving
Barrett has studied problem-solving in dreams for more than 10 years, and documented many examples of the phenomenon.
In one experiment, Barrett had college students pick a homework problem to try to solve in a dream. The problems weren’t rocket science; they were fairly easy questions that the student simply hadn’t gotten around to solving yet. Students focused on the problem each night before they went to bed. At the end of a week, about half the students had dreamed about the problem and about a quarter had a dream that contained the answer, Barrett said.
So at least in the cases where problems are relatively easy, some people can solve them in their sleep.
Barrett has also extensively reviewed scientific and historical literature, looking for examples of problems solved in dreams.
She found examples of almost every type of problem being solved in a dream, from the mathematical to the artistic. But many were related to problems that required individuals to visualize something in his or her mind, such as an inventor picturing a new device.
The other major category of problems solved in dreams included “ones where the conventional wisdom is just wrong about how to approach the problem,” Barrett said.
Dreams might have evolved to be particularly good at allowing us to work out puzzles that fall into those two categories, she said.
“I think that dreams and REM sleep have probably further evolved to be useful for really as many of the things that our thinking is useful for,” Barrett said. “It’s just extra thinking time, so potentially any problem can get solved during it, but it’s thinking time in the state that’s very visual and looser in associations, so we’ve evolved to use it especially to work on those kinds of problems.”
“Pharmagarden” - Robert Steven Connett
The BMC team inspect the new course layout for the Ronde
