The Space and Astronomy Thread

Heads up. There is a new documentary about the Challenger disaster on National Geographic tonight.
 
Ricardodaforce said:
Where are all the aliens? This story has being doing the rounds this week. Interesting point of view. http://www.universetoday.com/127032/127032/?utm_source=dlvr.it&utm_medium=facebook
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It's not that much of a story though, is it.

The whole so-called Fermi Paradox springs from conjecture about the Drake Equation. Many people seem to think that the Drake Equation implies that there ought to be lots of alien civilisations out there, but the reality is that most of the terms in the Drake Equation have essentially zero evidence to support any speculation about their values. We really only understand the first few terms in the equation - number of stars, probability of stars having planets, probability of planets being in the Goldilocks Zone - and even the last couple of them have really only been understood in the last 5 years or so. But as soon as you get deeper into the equation and the terms relating to life, intelligence, etc, there are no meaningful data. By the time we do understand these terms, it will be irrelevant.

There's one aspect of the Drake Equation which bothers me more than it seems to bother many scientists (who, admittedly, ought to know more about it than I do), and it's relevant here. It's the probability of intelligence arising. When you think about it, humans are more intelligent than all other species on earth by a ridiculous margin. Our intelligence clearly didn't arise from the need to cope with environmental problems or anything like that. There was something else going on. Probably that being smarter than your adversary allows you to plot against him in order to have more mates without being stronger or better at fighting ... but how probable is it that in evolutionary terms? In all of earth's history, in all the separate evolutionary experiments in Oceania and South America and Madagascar, this has only happened once. It wouldn't surprise me at all if it turned out that life is abundant in the universe, but intelligent life (i.e. intelligent enough to build radio telescopes, etc) is vanishingly rare.
 
StewartR said:
It wouldn't surprise me at all if it turned out that life is abundant in the universe, but intelligent life (i.e. intelligent enough to build radio telescopes, etc) is vanishingly rare.
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Or that the universe is teeming with intelligent life, but due to the vastness of space we'll never know.
 
StewartR said:
It wouldn't surprise me at all if it turned out that life is abundant in the universe, but intelligent life (i.e. intelligent enough to build radio telescopes, etc) is vanishingly rare.
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Ricardodaforce said:
Or that the universe is teeming with intelligent life, but due to the vastness of space we'll never know.
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What makes a chance vanishingly rare? 1/10^20? How many stars exist/have existed? Estimates seem to vary by several orders of magnitude but taking a bad average it seems to be somewhere around 10^20, give or take a few zeroes. That makes the probability pretty much evens doesn't it? As Ricardo says, intelligent life might exist - even be common - throughout the universe (?omniverse?) but a long, long way away so never the twain shall meet! Hell, if they're anything like us, all they'll want to do is cut us up to see how we work (or taste...)
 
Ricardodaforce said:
that the universe is teeming with intelligent life, but due to the vastness of space we'll never know.
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I very much doubt it. I would argue intelligence is not a good indicator of survivability - if the earth underwent some mass extinction event ( nuclear war, plague, a large comet impact, ice age triggered by mega volcanic eruption etc etc) then the lower down you are in the biological intelligence league the better your survival chances - if the earth is put under very extreme stress than in the end it would be the likes of bacteria that will have a higher chance to survive.
If life does exist on other planets then as it evolves into higher intelligent forms the more likely it is to be squashed out by either its own progress or some natural catastrophic event. I think this is probably the reason why we have not heard from other intelligent forms.
 
There's the time issue as well.
How likely is it that one intelligence will be around at the same time as another? It might only takes a few tens of thousands of years for civilisations to rise and then disappear as if they had never existed.

Maybe we are the first (like the Arisians) and will become the Caretakers of the Universe!
 
kendo1 said:
There's the time issue as well.
How likely is it that one intelligence will be around at the same time as another? It might only takes a few tens of thousands of years for civilisations to rise and then disappear as if they had never existed.
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My thoughts exactly. If a meteor hadn't wiped out the dinosaurs we might not have evolved or the evolution of intelligent life on earth may have happened millions of years sooner or later.
 
The news on this is a little old now but the estimated effects are mind boggling.

From Scientic American
"Astronomers have glimpsed the most powerful supernova ever seen, a star in a galaxy billions of light-years away that exploded with such force it briefly shone nearly 600 billion times brighter than our Sun and 20 times brighter than all the stars in the Milky Way combined. The explosion released 10 times more energy than the Sun will radiate in 10 billion years.

If the supernova took place in our own galaxy, it would be easily seen by the naked eye even during the day; if it were 10,000 light-years away, it would appear to us at night as bright as the crescent Moon. If it were only as far away as Sirius, which at a distance of 8.6 light-years is the brightest star in the nighttime sky, it would blaze overhead almost as powerfully as the Sun. If it were as close as Pluto, it would vaporize the Earth and all the other worlds in our solar system."

Dave
 
Another of the 12 moonwalkers has left us. Edgar Mitchell has died.
 
Ricardodaforce said:
Or that the universe is teeming with intelligent life, but due to the vastness of space we'll never know.
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There are no "others" out there that's just a ridiculous notion. If you entertain these notions you really do need to move to the USA.:eek:
 
32 years ago today Bruce McCandless flew untethered from the space shuttle. Some of those images of him floating in the void of space are now some of the most iconic of space photographs. One can only imagine what he experienced.
 
For you podcast fans, I just noticed that the BBC World Service have a space podcast series available for download.
 
The way that time and space works, if an alien ever did visit the earth today, the chances are that it would be able to look back at its own galaxy/solar system as it existed many hundreds of million years ago.
This then poses another question. If aliens were indeed able to travel here, then they would not be detectable by eye, because they would be travelling faster than the speed of light.
This is all before we get on to the more complex matter of the existance of lifeforms, the conditions needed to support life, how many diminesions exist in space, is time travel possible.
If aliens did manage to get here, then they would have to be incredibly advanced compared to humans, not just as far as technology is concerned but also physiology and their intelligence systems.
 
So why are they after our cows?
 
andy700 said:
The way that time and space works, if an alien ever did visit the earth today, the chances are that it would be able to look back at its own galaxy/solar system as it existed many hundreds of million years ago.
This then poses another question. If aliens were indeed able to travel here, then they would not be detectable by eye, because they would be travelling faster than the speed of light.
This is all before we get on to the more complex matter of the existance of lifeforms, the conditions needed to support life, how many diminesions exist in space, is time travel possible.
If aliens did manage to get here, then they would have to be incredibly advanced compared to humans, not just as far as technology is concerned but also physiology and their intelligence systems.
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They could have brakes and slow down so we'd see them. The speed at which technology is advancing on Earth now we could very well have the ability to travel at light speed and faster in a universally short time.
 
Steep said:
Back on track, hundreds of new galaxies seen for the first time, previously hidden by the Milky Ways bright bulk - artists impression from http://www.space.com/31872-hidden-galaxies-behind-milky-way-revealed.html
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Thanks for that.
A good link - the video was useful but a little simplistic. Since the wavelength of radio waves is much longer than visible light I assume they must have used some form of interferometry to increase the effective linear size of the receiving data base line. Does anybody know how far apart the presumably linked radio telescopes were ?
 
Ricardodaforce said:
Science Explained: How Can the Diameter of the Universe Exceed its Age?


http://futurism.com/how-can-the-diameter-of-the-universe-the-age/
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Thanks for that. How the size of the universe can be bigger than the observable horizon is an interesting feature of inflation ( as compared to cosmic expansion). I'm sure you are already aware the the flip from a quantum dominated early universe to the slightly later GR dominated one is presently not well understood.
 
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