Global Cooling, Global Warming
Aug 8 at 2:02pm by Aileen
Researchers from Oregon State University and other institutions have published an article in the journal Science that they say puts to rest a long scientific debate on the causes of periodic ice ages in the history of our planet. The conclusion? Earth Wobbles.
The last major ice age reached its peak about 26,000 years ago, held steady for about 7,000 years, then began melting 19,000 years ago. The melting was caused by an increase in solar radiation, the researchers say, and not by carbon dioxide’s “greenhouse” effect, or any changes in ocean temperatures. These mechanisms have been cited recently by some scientists trying to understand what appears to be happening now with the increase in global temperatures termed “Global Warming” and said to be caused primarily by pollution from human activities.
The researchers analyzed 6,000 dates and locations of ice sheets to define when they started to melt. This confirmed a theory developed more than fifty years ago that held small but definable changes in Earth’s rotation as the trigger for both the accumulation of ice and its melting cycle. Putting that together with changes in the Earth’s axis and rotation going back 50 million years, they found that the gravitational influences of the larger planets – primarily Saturn and Jupiter – leads to predictable cycles.
Right about now, the scientists say, we should be changing from an interglacial period toward conditions that will ultimately lead to another ice age. That is, if human contributions to Global Warming don’t thwart the process. Meanwhile, a close look at plans to mitigate global warming with ‘Geoengineering’ suggests that such plans may well do more harm than good.
Research presented at a symposium at the Ecological Society of America’s annual meeting concludes that geoengineering is potentially dangerous, and that the risks outweigh the benefits. Plans such as limited nuclear detonations and subsequent fires to release lots of carbon into the atmosphere, seeding the atmosphere with light colored sulfur particles to mimic gigantic volcanic eruptions, and seeding the oceans with iron to increase carbon uptake all come with side-effects that could be disastrous, ecologists say.
Indeed, if we are starting to ‘wobble’ to the gravitational tune of our giant planetary neighbors toward another ice age, taking big efforts to cool the planet right now could actually speed up the process! Perhaps we should put off the big projects until we know more about all this, eh?
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What Does It Mean for a Singularity to be Naked?
Mar 2 at 8:08pm by Aileen
Almost everyone who is interested enough to follow scientific developments is familiar with the good old “Black Hole” in space. This is what happens when massive stars collapse in on themselves and there’s nothing to stop it. Eventually all the mass gets crushed to infinite (or near infinite) density, creating a “Singularity.” This tiny point in spacetime exerts all the gravity of all the mass that became part of it, so their effects can be observed on other stars and matter near them.*
[* High energy physicists have suggested that singularities can come in much smaller 'mini' and 'micro' size, and are hoping to produce one at CERN if they ever get the Large Hadron Collider going.]
These black holes are said to be hidden behind an event horizon, where matter and energy being sucked in toward the singularity exceeds the speed of light. Beyond that boundary of spacetime, nothing within can ever get out again. Roger Penrose came up with the Cosmic Censorship hypothesis back in the ’70s when he and Stephen Hawking were formalizing the solutions to Einstein’s equations that predicted the existence of black holes. It seemed ‘indecent’ to Penrose that a singularity might ever exist that was not shielded from outside view by an event horizon, and that view predominated research for decades despite whispers here and there that naked singularities could indeed exist.
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Reality Might Be a Hologram
Feb 5 at 4:04pm by Aileen
Researchers at Cardiff University have managed to confirm a prediction made before the British-German gravity wave detector GEO600 was up and running, and it just might open up a whole new era in fundamental physics.
The press release Cardiff researchers could herald a new era explains that the GEO600 detector has been receiving some mysterious ‘noise’ that might confirm that the true nature of the universe is holographic, as predicted by physicist Craig Hogan at Fermilab. The GEO600 team is now gearing toward further experiments that may lend further evidence in favor of this theory. New Scientist has a more in-depth article, Our world may be a giant hologram that fleshes out the concepts.
Physicists have long hypothesized that the universe is ‘grainy’ at the Planck level, which is the smallest conceptual unit of space and time. Scientists cannot hope ever to measure phenomena at that level, but if the universe is a hologram projected from those tiny “grains of sand” they may well be able to detect levels of the projection as far into the high energy/small size range as they can ever go. That projection, Hogan maintains, is the source of the noise in the detector.
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The Chicken-Egg Question Goes Galactic
Jan 12 at 6:06pm by Aileen
Hi-res infrared composite of galactic core
Atronomers and astrophysicists determined some years ago – after that strange beastie known as a “black hole” was accepted to probably be a real physical phenomenon, that there are gigantic black holes at the center of galaxies. Moreover, they found they could determine the mass of these galactic black holes via a fairly simple ratio between the mass of the central bulge of stars and the hole they surround (about 1:10,000). It has been presumed that the hole at the galactic center got there by the joining of stellar mass black holes, which then continued to grow by accretion of mass from the stars drawn into the gravity well.
More recently, however, scientists examining galaxies much farther away in space and time found a different pattern. The farther back into the history of the universe they looked, the ratio between galactic black holes and the mass of the stars surrounding them did not follow the 1:10,000 ‘rule’ – the holes account for much more of the mass, meaning they were huge even way back in the early days of the universe.
As quoted in Wired’s article Yo Galaxy’s Mama Is a Black Hole, astronomer Chris Carilli of the National Radio Astronomy Observatory said during a briefing at the American Astronomical Society’s annual meeting that “The simplest conclusion is that the black holes come first and they somehow grow the galaxy around them.”
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Busy Week in Astro-News
Apr 4 at 6:06pm by Aileen
The annual meeting of the UK’s Royal Astronomical Society’s National Astronomy Meeting in Belfast this week has produced some cool news items on the astronomical discoveries of the past year. First up, we have some interesting findings in our own neighborhood with research focusing on our sun. An international team announced that they’d discovered the source of the solar wind.
The solar wind consists of electrically charged particles that flow away from the sun in all directions. The scientists working with the Hinode mission and the UK’s Extreme Ultraviolet imaging Spectrometer to determine that the sun’s magnetic fields create bright regions of activity on the solar surface. The edges of these bright regions emit hot gas at high speeds. The magnetic fields connect even in separated regions, and this connection (or collision) allows hot gas to escape from the sun’s gravitational field as solar wind.
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Our Universe: Missing, Found, Then Missing Again
Nov 8 at 10:10pm by Aileen
Keeping Up With Astronomy’s Game of Hide-and-Seek
Big astrophysics science news this week that a Big Chunk of the Universe Is Missing – Again. This requires a little background for understanding how it is our universe can be so adept at playing hide-and-seek.
As much as 96% of the mass necessary to account for how our universe is observed to be has been missing for a long time. The mass is necessary to explain the gravity that holds galaxies together, but all the atomic matter we can see in planets, comets, asteroids, assorted space junk, stars and galaxies accounts for just 4% of it. In 1974 astronomer Vera Rubin discovered that instead of following a Newtonian scheme where Mercury travels faster around the sun than Neptune does, almost all stars rotating around a galaxy’s center – at any distance – all travel at the same speed.
There had to be some ‘extra’ source of gravity working in galaxies, but there wasn’t nearly enough mass to account for this anomaly. The choice was between gravity being variable (unthinkable!) or the existence of a great deal of extra mass that we couldn’t see. Scientists jumped on that answer in defense of Newtonian/Einsteinian gravity and gifted us with “Dark Matter.”
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