Lady MacDuff

I happened to catch a program on the Discovery Channel last night called "Unfolding Universe." It covered the Big Bang, formation of the stars and galaxies, and went into great detail about the (doomed) future of our planet, solar system and galaxy.

Any teachers out there might want to tape it or order it for classroom use - it was geared toward education and gave a general overview of current scientific evidence and absolutely NO MENTION OF ANYTHING DIVINE.

In addition, UU helps point out the fact that the existence of life on this planet is simply a HUGE accident. There is no reason for it, and life will not be here forever. The program decribes how our solar system will one day (in maybe 5 billion years, I think?) be sucked into a massive black hole, and all evidence of there ever being an Earth will be completely wiped out.

Knowing this can make one feel kind of insignificant, but it also shows why we should value our extreme luck in existing at all.

Anyway, just wanted to point out that show. Check your TV Guide!

Liquidrage

I saw it. Actually it was one of the few shows I planned in advance to watch.

Of course I've come to expect this from TDC/TLC.
This wasn't on par with their "Walking with ..." series or their incredible ocean series Blue Planet, but it was sitll very good.

They do give air time to theistic documentaries that are usually pretty well done, and are willing to give some air time to psuedo science such as Chariot of the Gods. But overall I feel lucky to have channel that puts science into so many homes.

[ June 04, 2002: Message edited by: Liquidrage ]</p>

Dr Rick

I watched it last night and enjoyed it.

Rick

lpetrich

It's somewhat interesting to calculate the likelihood of various possible disasters that the Solar System may eventually experience.

The Sun is slowly getting brighter, and about 5 to 7 years from now, it will become a Red Giant, staying in that phase for a few hundred million years. It will blow off its outer layers, becoming a white dwarf and slowly cooling.

Its surface temperature will be approximately 3500 K (t / 11 Gyr)^(-1/2) assuming a simple theoretical model for a white dwarf's heat capacity.

As the Sun moves through the Galaxy, it passes by other stars, and in about 10^15 years (1 million Gyr), one of these stars will pass within 1 AU of the Sun, possibly pulling the Earth into a very eccentric orbit or liberating it from the Sun.

Also, the planets emit gravitational radiation as they move around the Sun; the Earth will fall in about 10^22 years from now, though it will more likely be ejected from the Sun by some close encounter of the interstellar kind.

The Earth will wander in interstellar space among stars that are all burned-out, being either white dwarfs or neutron stars or black holes. If the Earth moves too close to any one of them, it will be pulled apart by that object's gravity that distance for a solar-mass object is about 500,000 km, and that will likely happen in about 10^18 years, a billion billion years.

As a result of near-collisions with the stars, the Earth may be given enough velocity to escape the Galaxy, but I'm not sure what the timescale for that is.

But if it does not escape, then it will emit gravitational radiation as it orbits the Galactic center, and will spiral in after something like 10^37 years, so it is more likely to be ripped apart in a near-collision.

I now consider the fate of the Sun, which will be a very cold "black dwarf" by the time the Earth either meets its end or escapes the Galaxy.

The Sun will likely collide with another white dwarf in about 10^20 years; some of the two stars' material may be thrown off, with the non-thrown-off part becoming a black hole.

However, the Sun emits gravitational radiation as it orbits the center of the Galaxy; it will fall in after about 10^31 years. But it will likely collide with another white dwarf first.

Also, the Sun, like the Earth, may escape from the Galaxy as a result of its near-collisions with stars.

Finally, black holes are expected to evaporate as a result of quantum-mechanical effects, producing "Hawking radiation".

A solar-mass black hole will last about 10^64 years, meaning that such a non-escaped hole will fall into the center of the Galaxy by graviational radiation before that happens. As a result, the central hole will fatten from 10^8-10^9 solar masses to 10^11 solar masses. This will make it last 10^97 years.

So in 10^100 years, the Universe will have dissolved into an extremely thin soup of elementary particles -- truely a Goetterdaemmerung / Ragnarok.

Autonemesis

[code]
Friday 6/7
5:00 pm Miracles of Faith
Scientists try to explain amazing
religious acts; the Shroud of Turin
6:00 pm Physical Feats
Human endurance reveals incredible acts.
7:00 pm Between Life and Death
Possibility of life after death.
8:00 pm - 10:00 PM - REPEAT
</pre>[/quote]

They do this a few times a month. That's pretty sad for a so-called science channel. Now they have another set of channels devoted to broad areas of interest, and Discovery Science channel - sorry, it's just Science channel now - they even run this sort of program. It really frosts me and I have actually written them a letter complaining. But that only makes me feel better, they do what they want regardless. Now on to get SciFi to drop that John Edwards fraud... at least that's on the science fiction channel.

I didn't see the Unfolding Universe, though I saw the promos. TiVo to the rescue... look at the schedule, there it is, click click, all set.

[ June 04, 2002: Message edited by: Kind Bud ]</p>

Lady MacDuff

I have to admit to watching "Crossing Over" a couple of times. It's funny how the people in the audience get all excited when he says things like "Is there a John in your family...or a J name?" Everyone perks up. Then it's "Someone died suddenly from a heart problem and wants you to know he loves you." Everyone gets weepy. There is probably not a single family in the U.S. without a dead John in their family or someone who died from a heart attack! Entertaining but sad - it's about as real as Animal Planet's "Pet Psychic."

The Lone Ranger

Well, there go all my future plans! {Actually, I think you meant 5 - 7 billion years.}

I read recently that, because the Earth is slowly being pulled into tidal locking with the sun, within 500 million years or so, the Earth's rotational period will be so slow that the temperature extremes between the day and night sides will be so great that the Earth will no longer capable of supporting life as we know it. (Except bacteria, maybe.)

On the other hand, it's a bit hard to get all worked up about something that won't take place until we're all long-since turned to dust.

Cheers,

Michael

lpetrich

That's right -- it's a rather stupid typo.

lpetrich

The eventual fate of the Earth is certainly an interesting question. There are two effects that will make the earth uninhabitable by most life about 500 million - 1 billion years from now, according to some estimates.

* The first will be the carbon-dioxide thermostat reaching its limit -- no carbon dioxide. This thermostat is a favorite hypothesis why the Earth has had liquid water for the last 4 billion years, despite the Sun having been dimmer than today -- about 75% of present-day luminosity back then.

According to this mechanism, the atmosphere had had more CO2 in its atmosphere back then, and maybe some additional greenhouse gases like methane. But the Earth's surface did not get too hot, because CO2 is consumed by the weathering of eroded rocks, which proceeds faster at higher temperatures. Thus, the thermostat effect.

But as the Sun gets hotter and hotter, the Sun supplies more and more heat to the Earth, meaning that less and less CO2 is needed to reach the weathering limit. Eventually, the Sun will be hot enough so that the weathering limit will be at zero CO2, meaning that the only CO2 in the atmosphere will be from recently-erupted volcanoes.

And we are close to that point; the present-day concentration of CO2 in the atmosphere is 0.03%.

* The second will be water getting into the upper atmosphere as its temperature increases along with the Earth's surface. This wil expose it to the Sun's more energetic ultraviolet photons, which will split them apart. The hydrogen will escape into outer space, gradually draining the Earth of water, until it becomes a bone-dry desert. However, that may slow down the rock weathering, allowing CO2 to accumulate in the Earth's atmosphere again, eventually giving the Earth a Venus-like atmosphere.

And as the Sun enters red gianthood, all of the Earth's atmosphere will evaporate and the Earth's surface may melt from the Sun's heat.

Answerer

Damn, sometimes, I regret the fact that I'm not an American.