Stellarator wrote:

Source of the post HKATER wrote:
I don't subscribe to global warming, ecological distaster, pending doom as a factor.

In light of my exposition in the above paragraph, these would literally be the ONLY reasons humanity would want to escape the solar-system altogether.

I don't think so.  The worlds out there, whether with life or not, will be environmentally hostile to humans and fixing whatever problem we have on Earth is extremely more likely easier.  Some argue that the hostile environments can be fixed by terraforming or genetic engineering, but again, if those technologies exist, it will be much easier to use them on Earth to fix the problem here instead.

As for the chances of life on other planets, I think it's rare in the sense that if you pick planets by random, the vast majority will be lifeless.  Even if you could visit one new random planet per year, I suspect that you still need some luck to encounter life in your lifetime.  On the other hand, there are so many planets out there that it would be very surprising that Earth is the only one with life in the Milky Way.  As for intelligent life, it can be extremely rare considering how much time it took on Earth to come about and then how quickly it evolved, which indicates that the evolutionary path to intelligence is not very stepwise and certain.  And interstellar faring life is possibly so rare that it doesn't exist apart for the possibility on Earth.  Even intelligent life could exist in multiple places in the Milky Way and nothing would become interstellar.  That intelligent life could be oceanic, and space travel for them would be to explore the surface, and for them leaving the atmosphere would be as hard as leaving the solar system for us.

midtskogen wrote:

Source of the post I don't think so.  The worlds out there, whether with life or not, will be environmentally hostile to humans and fixing whatever problem we have on Earth is extremely more likely easier.

Agreed.  This was one of the things that irked me with the premise of the film Interstellar.

midtskogen wrote:

Source of the post I don't think so.  The worlds out there, whether with life or not, will be environmentally hostile to humans and fixing whatever problem we have on Earth is extremely more likely easier.  Some argue that the hostile environments can be fixed by terraforming or genetic engineering, but again, if those technologies exist, it will be much easier to use them on Earth to fix the problem here instead.

I totally agree:

Stellarator wrote:

Source of the post All also have solutions that don't involve calling a grand "RETREAT!" from the solar-system.

Watsisname wrote:

Source of the post This was one of the things that irked me with the premise of the film Interstellar.

That, and the fact that the habitable planets orbit a black-hole . I mean, don't get me wrong, a blackhole could support a habitable zone and indeed an artificially fairly stable one at that, but the distance and nature of the one in the film was just wrong. 

In addition, why did the schools on Earth all of a sudden decide to teach the kids that we never went to the Moon? It was a subtle part of the movie's beginning, so easy to miss. Perhaps the reason was that at the point of Interstellar's timeline, the space-program had atrophied in the public eye (despite them still having resources to build and pilot a wormhole-going vessel) to such an extent that it was ludicrous for people to believe they had done anything ever. But, why couldn't the Apollo missions be motivational instead of demoralizing?

Stellarator wrote:

Source of the post I mean, don't get me wrong, a blackhole could support a habitable zone and indeed an artificially fairly stable one at that, but the distance and nature of the one in the film was just wrong. 

Actually, the film was (more or less) correct on this matter.  Gargantua is massive enough (10⁸ solar masses) for all possible stable planetary orbits around it to be outside of its Roche limit, as I show here.

But what about heat and illumination with the so-called habitable zone?

Looking at the space.com article you linked, it assumed the only sources of light are stars orbiting the black hole.  That's ridiculous.  They neglected light from the accretion disk, and a black hole closely orbited by stars will be actively accreting.  Black holes that are not in isolation are not black!  That's how we are able to discover them.

For their first case of a close binary Sun and stellar-mass black hole, the black hole would be accreting at close to its Eddington limit of 10³¹ Watts, or about 30,000 times the luminosity of the Sun.  What the article claims would be a habitable zone would be a vaporization zone.  Even tungsten would melt.

For supermassive black holes like Gargantua, the Eddington limit is about 10¹² times the luminosity of the Sun.  Obviously bad for nearby planets -- or even planets several light years away.  However, the film portrays the black hole as having a very low accretion rate with a "quiescent" disk, more conducive to supporting planets around it.  Whether such a low and stable accretion rate and the presence of planets in orbits around it are realistic outside of artificial tinkering is another matter of course...

Another fun thing about the accretion disk which the film did get right is that the gravitational lensing brings the whole disk into view, regardless of viewing angle.  So from afar the disk really does act like a sun.

Watsisname wrote:

Source of the post Looking at the space.com article you linked, it assumed the only sources of light are stars orbiting the black hole.  That's ridiculous.  They neglected light from the accretion disk, and a black hole closely orbited by stars will be actively accreting.  Black holes that are not in isolation are not black!  That's how we are able to discover them.

For their first case of a close binary Sun and stellar-mass black hole, the black hole would be accreting at close to its Eddington limit of 1031 Watts, or about 30,000 times the luminosity of the Sun.  What the article claims would be a habitable zone would be a vaporization zone.  Even tungsten would melt.

Hmmm, scientific journalism failed me again. I think I need to refer to my physics and astronomy text books more .

Hey Watsisname, have you ever been to the Channeled Scablands, in the eastern regions of your state? Aside from being historically interesting, they look like they would be great for hiking through:

Stellarator, yes, I've been through many parts of them!  Mostly from along the roads and highways.

The landscape is both desolate and fascinating, especially when you imagine the (lava) flood basalts that formed them, and then the (water) floods that carved through it later as PBS Eons describes. The scale of both events is almost unfathomable.  Here's a random boulder sitting conspicuously in a meadow, rolled there by one of the floods as he talks about in the video.

It is also a tremendous contrast to the lush western side of the Cascade range.  To be honest I think the scablands are better to drive through than to hike through, mainly because of how vast they are, plus the aridness and temperature fluctuations.  It is quite desert like, and in summer it can easily reach over 40C during day and drop below freezing at night.  And again, it can be very desolate:



Many areas out there also have very dark skies and are great for astrophotography.   I took this shot of the Milky Way from the scablands south of Ritzville a few years back:

Watsisname wrote:

Source of the post It is also a tremendous contrast to the lush western side of the Cascade range.

Ah, yes. It does remind me of the transition between the Kootenays and the Okanogan here in BC, but in reversed directions. On the east side there are the lush rainforests, and in the west there is the Okanogan valley - which basically resembles Australia. Fun fact about the Okanogan: for decades, there was this Ostrich breeding farm near the boundary. In recent years, some of the Ostriches have broken loose and now the Okanogan looks like the Serengeti more then ever .

Watsisname wrote:

Source of the post Many areas out there also have very dark skies and are great for astrophotography.  I took this shot of the Milky Way from the scablands south of Ritzville a few years back:

I'm green with envy . The Kootenays are horrid for astrophotography.

I think for us to be able to expand outward into space, especially to other solar systems not only will require a huge technological leap, but also a cultural/economical/societal one.  Our current political/economical systems will be considered quite archaic, primitive, wasteful and out of date by our descendants who finally do it.

About intelligent life taking so long to evolve on Earth, maybe if we didn't have all those pesky mass extinctions it would have happened much earlier.  Imagine if the K-T event hadn't happened, with dinosaurs or their descendants evolving intelligence (they were already beginning to) we would have gotten a 65 million year head start!

I think there should be at least a half dozen space-faring civilizations in each galaxy, but there would be no reason for them to want to come here, we are in the rural part of the galaxy.

Some of them might not even be organic or may exist in interstellar space as opposed to on a planet or be composed entirely of energy or exist on the quantum scale- we would not be able to detect most of these!

Wat, direct interstellar travel may be impossible, but besides the Alcubierre Drive if we ever are able to construct traversable wormholes Kip Thorne style, we may find a way around it.  Also, perhaps paradoxes can be resolved by use of MWI, instead of creating paradoxes you simply branch off into a different timeline of the same universe. In other words, if you for some inane reason want to kill your own grandfather, he wont be the same grandfather who was your ancestor, he will be from a different timeline.

Stellarator, I like the hypersphere idea also, and the fact that it could also resemble a toroidal shape.  About other universes being somewhat similar (especially if they are adjacent), I can only refer to Alpha Centauri A being similar to our sun.  Perhaps being adjacent means a similar environment can create a similar universe (with the obvious caveat that it's a multiple star system so there would obviously be some differences.  I just see photons as something that should exist in every universe since light is so basic to everything we know.)

About time before the Big Bang, Stephen Hawking had some interesting ideas with his Imaginary Time, which solves the singularity problem by extending the time line back before the Big Bang and making it more of a Bounce than a Bang (like the Origin point of a Cartesian coordinate system- thats actually where I got the title for my Origin series.)

As far as other universes even cursorily interacting with ours, there may be hints of that in the CMBR.  I agree about other universes being superpositional, thats what I meant by adjacent, not the border thing (not like the border between two nations at any rate lol.)  What about particle universes?  The idea that any "particle" we can imagine is actually a whole new universe unto itself and that our universe is just a particle in another universe?


My favorite numbers are pi, 15, 42 and 137!  I truly loved this discussion of mathematics- it proves our universe is mathematical and numbers like pi mean something on the cosmic scale too!  It's interesting you mentioned magic numbers- dont we also have this with newly discovered chemical elements that are created in the lab and certain ones with magic atomic numbers and masses exist on islands of relative stability?

A-L-E-X wrote:

Source of the post and the fact that it could also resemble a toroidal shape.

It cannot be toroidal.  There are only 3 allowable shapes to the universe -- flat (Euclidean), constant positive curvature (hyperspherical), or constant negative curvature (like the curvature of a saddle point, but everywhere, for which there is no analogous shape you can visualize.)

A-L-E-X wrote:

Source of the post with dinosaurs or their descendants evolving intelligence (they were already beginning to)

I don't think there is any evidence that dinosaurs were smarter than, say, today's birds, and even though some birds are pretty smart, like the crow family, there is no evolutionary necessity that they will develop this intelligence further to become capable of space flight,

One critical part of human evolution besides intelligence is that we have arms and fingers enabling us to manipulate and use tools.  Dinosaur arms weren't so practical, even at a time when it was already present in mammals.  In that respect, mammals already had a head start, and with dinosaurs out of the way, mammals could more easily diversify.

midtskogen wrote:

Source of the post Dinosaur arms weren't so practical,

I'm tempted to disagree here on principle alone. The arms of most herbivorous dinosaurs were indeed stumpy and of limited use for anything aside from walking, wacking and slapping - and of course the infamous arms of tyrannosaurs and abeloisaurs are simply woeful. But some other species of dinosaur, particularily those in the maniraptorae group (of which the Dromaeosaurs and troodontids are key members in this regard) were surprisingly dextrous and skillful at at tasks, some as much as primate hands. In the spoiler below, the tridactylated forelimbs of a Deinochyus are compared to those of an Archaeopteryx - and one clearly see in both species the highly maneuverable nature of the fingers. This flexibility would have allowed for all-finger grasping, single-digit dexterity and some wrist articulation.

In addition, a few troodontid species and a dromaesaur we know from a single fossil named Bambiraptor feinbergi (which might be a juvenile of the larger Saurornitholestes sullivani species) had partially opposable thumbs. These maniraptors were the most intelligent archaosaurs on the planet, and while they were not smarter or as smart as modern birds as you said, they were certainly competant in their environment. Perhaps, given some more time, they could have started manipulating objects with these forelimbs along with their mouths.

Also, while opposable thumbs are the most useful digits for tool use, there are many other apparently intelligent species on Earth that get by just fine without them .

Black holes have surface? I mean, if someone were powerful enough to resist its attraction would he be able to touch it?

Hewerton22 wrote:

Source of the post Black holes have surface?

No, they don't have a physical surface. The 'black' part of the blackhole isn't actually a 'piece' of something. It's just the represents the boundary from which light cannot escape from (the Event Horizon). There is still 'something' beyond the black part, you just can't see its photons from the outside, so it's just a black hole.

It's like the "atmosphere" of the object, right? But it's very dense.