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Space Is Full of Planets, and Most of Them Don't Even Have Stars

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Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#161

Post by ASalazarMX »

tiemand wrote: post #146
rpedela wrote: post #130

Earlier quoted context omitted.

I generally don't like the assumption that life had to come from space because we don't know how life is created and it appeared so soon in the history of Earth. That is certainly a possibility, but it also possible that creating life from chemistry is easy. Just because we haven't figured it out yet doesn't mean it is hard. Obviously figuring out how it works is hard, but the mysterious mechanism may be simple.

One problem I have with pan-spermia is: Why is there only one tree of life? Not several independent trees. If life evolved in one of the exo-planets, is not possible that several independent forms of life evolved in several planets and some ended up on Earth.

I also don't subscribe to panspermia because first local origin must be reasonably proved unfeasible, but playing devil's advocate ¿what if our life tree outcompeted the others?

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#162

Post by cobbzilla »

sudhirj wrote: post #94
cobbzilla wrote: post #88

Earlier quoted context omitted.

to a point you are right, but clearly there is some boundary, right? imagine a solid object with a mass just below the Chandrasekhar limit and a temperature near absolute zero. Don't tell me hurtling that into the Sun will make it burn hotter. And even if it would (or a smaller object) in the long run, there would at least be some period of time before the incoming matter reached fusionable temperatures, reducing pow…

Seems unlikely for fusion. Think of it from the point of view of star formation - the gas that coalesces into a ball is already super cold from floating around in space. The heat for fusion comes from gravity compressing the matter, not from the starting heat energy present in the matter itself. So yeah, you can't really add cold stuff to starts to extinguish them - stars are made from absolute ice to being with.

wow. i had never thought of it like that. thank you.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#163

Post by ASalazarMX »

sandworm101 wrote: post #151
tiemand wrote: post #146

Earlier quoted context omitted.

One problem I have with pan-spermia is: Why is there only one tree of life? Not several independent trees. If life evolved in one of the exo-planets, is not possible that several independent forms of life evolved in several planets and some ended up on Earth.

One tree (us) either appeared first and dominated resources, or we wiped our the other trees. Evolutionary forces work at levels above species. Two trees can compete with each other. If this happened it did so at the microbe level. Physical evidence would be extraordinarily difficult. If we did find evidence of another tree it would be so 'alien' to our tree that might mistakenly call it extraterrestrial.

And since panspermia is necessarily done with microbes, they would get outnumbered and munched by our microbes if they arrived after our tree dominated our planet. Unless other planets happened to give birth to hardier, more virulent microbes, then welcome Andromeda Strain.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#164

Post by ASalazarMX »

maxerickson wrote: post #149
hyperpallium wrote: post #75

Earlier quoted context omitted.

If you're a fan of Moore's Law and the Singularity, you'll love the reasoning of backtrapolating the exponentially increasing complexity of life over time... to get 0 well before the formation of the earth https://www.technologyreview.com/s/513781/moores-law-and-the...

I wonder if scientists in the future will ponder how microchips were invented before the steam engine.

"Aliens gave it to them". This puts panspermia in a new light, thank you.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#165

Post by RobertoG »

Tepix wrote: post #131
RobertoG wrote: post #119

Earlier quoted context omitted.

A main component of the paradox is time, but this paper solve that. Life existed from the beginning, but only now has become complex enough. So, we don't see or hear artificial signs in other galaxies because light is from the times when there was not complex life in the universe. Now, we only have to solve why we don't see or hear artificial signs in our galaxy. But the problem is not so perplexing because we are ta…

What are the odds that our life is the first that has reached sufficient complexity to be able to communicate within our galaxy? Given that there are 100-400 billion stars (and even more planets) just in the Milky Way: Pretty much zero.

The problem has been always the temporal scales. But if you change that, the odds are not so bad.

If all the civilizations started more or less at the same time that us, it's not so weird that we have not found anybody else. If you add some other factor (maybe civilizations are only possible far from the center, so there is a big spread between them) the probabilities improve.

It also would mean interesting times ahead for humanity.

Of course, all this is only idle speculation.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#166

Post by ChuckMcM »

cobbzilla wrote: post #60
ChuckMcM wrote: post #20

Earlier quoted context omitted.

Napkin math (aka pure speculation) suggests that unless the rogue planet hit the star directly and at an angle that could send ejecta our way, the results would be more observational than catastrophic. The Earth is roughly 333,000 times less massive than the Sun. Think of it this way, If an asteroid hit the Earth that was, in relative terms, the size of the earth relative to the sun, it would be about 1/3 the size of…

Let's say the rogue planet is a massive, super-cold planet. How big and how cold would it have to be to lower the Sun's energy output just enough to trigger a "Snowball Earth" scenario? Assume a direct hit.

I think the only way this works is if the planet doesn't hit the Sun. One could imagine a scenario (but the orbital mechanics don't work out) where a massive rogue planet enters into the solar system and interposes itself between the Earth and Sun, thus shading the Earth and dropping its temperature the required amount. Sort of like a month long solar eclipse or something. But at that mass it's probably pulling Earth out of its orbit so that scenario is not really very plausible.

If it hits the Sun, it really doesn't matter how cold or how massive it is (up until it becomes a brown dwarf at which point we're talking binary star interaction levels of mass).

The thing is that the Sun is really spectacularly huge. You could fit over a million earth size planets inside of it. And it is a run away fusion reactor so it is kind of like throwing frozen beer cans into a 500 acre California wildfire. Very little effect on the fire (although any embedded Hot Shot firefighters will appreciate your effort).

But things are even easier than actually hitting the Sun in this case. If you're trying to just screw up the Earth, any rogue planet that flew through the Solar system and pulled earth more than about 6 - 8% off its existing orbit should completely wreck the climate. If you were a fiction writer you'd want it to be bad enough that people could survive long enough to write a story about it or course.

Generally though any astronomical mass that would nominally qualify as a planet flying within a million miles of the Earth is going to likely trigger an extinction level event. Especially if it is off the ecliptic by some amount.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#167

Post by lev99 »

nabla9 wrote: post #41
lev99 wrote: post #32

Earlier quoted context omitted.

The article states that planets may outnumber stars 100,000 to 1. The Milky Way has 4E^11 stars. It has an upper estimate of 4E^16 planets. It has a lowest estimate diameter of 100kly. It has an estimated thickness of 2kly. It's lower estimate volume is 63,000 kly^2. ----------------------------- If planets are uniformly disrupted (they surely aren't), there are ~17 planets in every cubic light year. Sure, that's a h…

> ~17 planets in every cubic light year. The change of hitting one while traveling one light year is in the order of 10e-16.

A few things make me thing it's a much larger risk than 10e-16.

1. My numbers are on uniform distribution of planets. The milky way is not uniformly distributed, and I suspect this isn't either. I hypothesis most of the planets will be on the spokes, just like most of the stars are. In addition, while it is 2kly tall, there is not a uniform distribution across the height.

2. Interstellar travel doesn't involves traveling a minimum of 4 lys, and a maximum distance without being intergalactic would be about 100,000lys.

3. Your assuming instantaneous travel across the light year. In reality we would consume at least 1 year in travel time, and likely much more.

4. The amount of resources it takes to build an intersellar ship is very large. The cost of a collision is high. This doesn't change the risk of a collision, but it does change what we consider acceptable risk.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#168

Post by sunstone »

m_mueller wrote: post #91
hyperpallium wrote: post #75

Earlier quoted context omitted.

If you're a fan of Moore's Law and the Singularity, you'll love the reasoning of backtrapolating the exponentially increasing complexity of life over time... to get 0 well before the formation of the earth https://www.technologyreview.com/s/513781/moores-law-and-the...

What about Fermi's paradox though? I mean, where is everyone?

We are a baby civilization. Everyone is waiting for us to grow up.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#169

Post by restalis »

vorg wrote: post #124
brazzy wrote: post #56

Earlier quoted context omitted.

Quite the opposite, actually. At near lightspeed, a pea-sized rock will kill your spaceship just as dead as a planet. So you actually want your interstellar masses to be as concentrated as possible.

> At near lightspeed, a pea-sized rock will kill your spaceship Why travel in a spaceship? If there's 100,000 starless planets for every star in the galaxy, then travel between stars on one of them instead. Build the habitations 10 km below water to avoid radiation. Travel at 0.1% light speed instead and get to the nearest star in 5000 yrs. Enjoy the journey, and slip into an orbit around the target star. Speaking of…

"periodically fire one laden [rock] with electronics/optics/quantumics at the target star at near light speed and receive its transmissions for recon"

These would act as space weather beacons, forming some kind of illuminated space (high)way. An interesting idea!

As for the rogue planets, although I envision humans having some use for them, I doubt it will be for interstellar travel the way you describe.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#170

Post by restalis »

baxtr wrote: post #25
beamatronic wrote: post #9

Earlier quoted context omitted.

Could you provide an example? I don’t recall such an episode.

“It is unclear how plant life could survive on Dakala. One scene, however, shows the surface covered in the dim light of a nearby star, perhaps supplying enough energy for some form of photosynthesis. Another theory, from the Star Trek Encyclopedia (4th ed., vol. 1, p. 177), is that the plant and animal life was supported by the surface heat from volcanic vents.“ From http://memory-alpha.wikia.com/wiki/Dakala

I thought that the volcanic activity is a phenomenon happening only in orbiting planets, due to a number of forces that include star's gravitational one.
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