Tag Archives: science

The Dimming Universe

by Mark Aragona

You don’t feel it, you don’t see it, but the universe is slowly growing colder and darker.

Using powerful Mopra radio telescopes, scientists in Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) have discovered that about a third of the molecular hydrogen that stars use as fuel has already been used up. By comparing light densities now to how they were 5 billion years ago, they have concluded that less stars are being born now than before. Apparently, the universe had reached its star-birthing peak after a few billion years and is now in the decline.

“We’ve seen a decline in the amount of stars being formed by more than a factor of 10, probably closer to 20 or even 30,” says Robert Braun, lead scientist of CSIRO. “It turns out that these galaxies actually had 10 times more gas with which to form the stars than they do today. We just aren’t seeing as much gas fall in to form the new stars.”

Braun’s team came to this conclusion by comparing older, more distant galaxies with the ones nearby. Galaxies burn interstellar gases they attract from the space in between them, but over time they tend to lose gas, particularly during events such as supernovae.

What’s more, the universe continues to rapidly expand due to the presence of dark energy, which has taken over the cosmos a few billion years back. Dark energy counteracts gravitational force and causes galaxies to accelerate away from each other, making it harder for them to find much needed molecular hydrogen to refuel their stars.

So what are the likely scenarios for an ever-dimming universe? It depends on whether the universe’s rate of expansion will remain as is or if it will accelerate.

Scientists say that the most likely event will be the Big Freeze, stated to happen if the universe maintains its rate of expansion. At around 1014 years after the Big Bang, no more stars will be born. For many more billions of years after that, all other existing stars will burn out, and even black holes dry up as the universe reaches the point of entropy. The universe will be nearly empty, save for electrons, positrons and dark matter.

Another possible scenario, described by a paper called “Phantom Energy and Cosmic Doomsday,” depends on the kind of dark energy existing in the universe. If it happens to be phantom energy, where the sum of the energy pressure and density is negative, the universe will expand at an exponential rate until it reaches singularity, opposite that of the center of a black hole. Phantom energy’s expansion will be so great that it will tear apart everything in the universe. First galaxies will pull away from each other, then the Milky Way will dissipate, followed by our own solar system. In the last few moments, the rate of expansion will reach infinity, pulling apart atoms, nuclei, and subatomic particles. This scenario is aptly called the Big Rip.

It’s strange and humbling to think that something as vast as the universe still has a lifespan. Perhaps humans won’t be around to witness it, perhaps they will. Perhaps we will even find some way to endure even when the last star fizzles out, as in Asimov’s short story, “The Last Question.” Or maybe another version of the universe will come into being. We may never know, but we can always dream.

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Saturn Moon May Have Saltwater Sea

Cassini

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By Mark Aragona

It seems that we don’t have to wander outside of our solar system to find planets that could possibly sustain life. A tiny Saturn moon may just be the place for it. The Cassini-Huygens mission has found that Enceladus, much like Jupiter’s Europa, may have an oceanic layer underneath its surface of ice.

Enceladus is a wonder in itself: a frozen white world, 0.0395 the size of Earth. The moon is the most reflective body in our solar system, reflecting more than 90% of the sunlight that reaches it and leaving the moon with a temperature of -330 degrees Fahrenheit (-201 degrees Celsius). Geysers on its surface shoot out ice particles in great white plumes that feed Saturn’s E ring. Scientists used this very phenomenon to find out what lies underneath the moon’s icy exterior.

In 2008, the Cassini spacecraft dove through Enceladus’s plume trail and found that it was made up of icy water. The real find came when they took a close look at the particles nearer the surface and found salt. In fact, 99% of the solids found in the plume were salt-rich material that resembled the kind found in our own seas. It’s likely that somewhere underneath all that ice, Enceladus has its very own ocean.

There’s more: the spaceship’s instruments have detected negatively charged ions in Enceladus’s icy plume. Professor Andrew Coates of the Cassini mission said: “While it’s no surprise that there is water there, these short-lived ions are extra evidence for sub-surface water, and where there’s water, carbon, and energy, some of the major ingredients for life are present.”

That means that Enceladus is one of three places in our solar system that so far have been found to have negatively-charged ions—the other two are Titan and Earth itself. Here on our own planet, negatively-charged ions are present where there is liquid water in motion, such as streams, waterfalls, and yes, oceans.

The two flybys of the Cassini spacecraft have also shown that Enceladus has an atmosphere. Because the moon is so small that it cannot hold that atmosphere down, scientists speculate that the geysers and ice volcanoes are continuously feeding gas to the surface.

NASA scientists have declared at an Encedalus Focus Group Conference that the Saturn moon “is emerging as the most habitable spot beyond Earth in the solar system for life as we know it.” Meanwhile, the Cassini mission is preparing for another close encounter with this enigmatic world. Here’s hoping that even if they don’t find life, they may at least guarantee a place for it.

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Solar ‘Hibernation’ Puzzles Scientists

The Enigma of Sunspots

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by Mark Aragona

Just when you thought there was nothing new under the sun, it turns out you were just looking in the wrong direction.

In a phenomenon not seen since the 17th century, solar activity appears to be undergoing a “quiet” period, marked by a lack of sunspots, sluggish solar flares, and slow activity around the poles. Scientists are baffled as they were expecting the opposite, a solar maximum, to occur around 2012.

Frank Hill, associate director of the Solar Synoptic Network, calls the events “highly unusual and unexpected.” Nevertheless, three different studies have approached the same conclusion after observing the sun’s atmosphere, insides and surface. Hill states that “solar cycles cause space weather which affect modern technology and may contribute to climate change.”

The first observation was that sunspots are fading away from the star’s surface. Sunspots are areas of relatively cooler temperatures which scientists have used for centuries to indicate the sun’s magnetic activity.

Observers have also noted that solar flares have been sluggish and that jetstreams that normally rush from the poles to the equator have slowed down to a crawl. All of these indicate that the sun is entering a state of “hibernation” and delayed start of the 25th solar cycle.

Questions have arisen on how this will affect our climate. Some scientists are saying this may be a second Maunder Minimum, referring to a period between 1645-1715 where Europe entered a mini-Ice Age, a time when canals regularly froze and glaciers crept across the land. Other scientists are more skeptical. They state that, firstly, the relationship between the sun and climate change is poorly understood, and secondly, that our carbon output is far higher now than way back in the medieval era.

Technology is also subject to space weather. Solar flares and other activity from the sun can throw highly-charged particles at the Earth, interfering with satellite signals, GPS, power grids, and other electronic devices. It even causes a drag on orbiting satellites. With a relatively quieter sun, we can expect better performance on all counts.

There’s still a lot to look out for. Scientists are now watching for what our star may or may not do next, particularly with regards to its magnetic field. The next few years under the sun may get very interesting indeed.

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