Nitpick, the continent you were thinking of is Rhodina, not Rhodesia. (which as far as I know, was never a continent?)
Anyway, you are right, Rhodina covered most of the planets equator at the time, which didn't allow for any warm water to flow to the north and southern regions of the planet, which allowed glaciers to grow and ultimately caused Snowball Earth. (Snowball earth in term ended when Rodina started to fracture up and disperse into various continents, allowing water to re-enter the equatorial regions)
Bah, close enough, Rodinia, Rhodesia, one of them the continent of doom, the other Cecil Rhode's personal country of chaos.
(and it was parked on the South Pole, not on the Equator, and the run away snowball effect started from polar land not retaining heat as well as water, and the increased albedo from the snow caused the increased cooling which lead to more snow and more albedo)
You have to be careful about THAT line of reasoning. Just because we have broken barriers we thought impossible in the past doesnt mean all barriers are breakable... we will at some point reach unbreakable barriers and intersteller travel may be just such a barrier.
I did not say all barriers can be broken. I am merely saying that assuming barriers cannot be broken and therefore never try is doomed to failure.
Assuming something is impossible and not trying is different from assuming something might be possible and trying until told otherwise.
I said 'earth like' and everything else aside, there is one key requirement that we cannot do without, an atmosphere, and more specifically a light element atmosphere. That requires a strong magnetic field, no if and or buts, and a strong magnetic field requires an active core, which quite possibly may require a large orbiting moon.
First off, you can have an atmosphere without a strong magnetic field (Venus). You just need volcanism to replace what you lose. Without volcanism is what makes a strong magnetic field essential, and that only increase the duration which your atmosphere lasts.
Secondly, a strong magnetic field only requires flowing charges. Flowing charges means a liquid conductive core, which is independent of whether or not a large moon is present. A large liquid conductive core only requires iron, and a large enough mass to retain heat, and rotating fast enough to maintain the magnetic field. I'm not entirely sure once every 38 days is fast enough, but it's within the realm of possibility. (Mercury has a weak magnetic field because it rotates fast enough around the sun, and has a large iron core that is probably stretched and pulled by its orbit around the sun to be partially liquid.)
Because this is a 3 earth mass planet, it certainly has the necessary mass.
Regardless, you can have settlements in an enclosed environment and ignore whatever the planetary surface conditions are, akin to Biosphere 2. Or even a space station if you are going to argue Biosphere 2 was a failed experiment, just that you need to include your food growing within the dome as well. It may be technologically prohibitive now, but most likely it won't be forever. (space tourism already exists today, but not widespread)
You arguing that you must be able to breathe the atmosphere unprotected to make it a feasible settlement is the same as arguing Scandinavia is uninhabitable because you cannot live outside exposed to the elements.
Again I said 'earth like' and I am suggesting that intelligent life can only evolve on a planet with a very large selection of life, it must have a complex animal life and plant life, complex animal life is NOT possible without an oxygen atmosphere.
Why must you have oxygen as a oxidizing agent? It is entirely possible using alternative chemistries, so don't discount them simply because they haven't been explored. It may not be as efficient as oxygen, but it is entirely possible.
We've got highly intelligent animals (octopus; they can't be more intelligent than they are now because they are plagued by short life spans and partially autonomous limbs, and they aren't particularly selected for intelligence) using highly inefficient circulatory systems compared to other animals, not to mention living in water which has less dissolved oxygen than air in the first place.
WHAT!?! We are only here because an oxygen atmosphere allowed the development of complex animals, we only have an oxygen atmosphere because of plant life AND a strong magnetic field to stop it from blowing away.
If you say "we" as in humans, we are only here because long ago our bacterial ancestors adapted to an atmosphere created by life that killed off the vast majority of life that required the absence of oxygen. The Oxygen Catastrophe forced an "survive oxygen or die" situation on life. Even now, oxygen is rather toxic in high concentrations. It is not required for oxygen to have advanced life, but it is one of the most efficient, so easiest to form advanced life with it.
Atmospheres depend more on the presence of volcanoes (which the period of volcanic activity primarily depends on its mass) for outgassing rather than magnetic fields for retention. Magnetic fields are great at retaining atmospheres, but if it's not being replenished, it's a losing battle.
Venus has a very thick atmosphere of CO2 at 90 bars. It also has no magnetic field.
Scientific estimates are 1 million stars within 1000LY... Drake himself estimated one civilization per million stars, that would be us, and IMO Drake was over estimating, I doubt the odds are that good.
Well, agree to disagree. I believe it was an underestimate, considering how rapidly life came into existence on earth (nearly instantly after the Late Heavy Bombardment period), how there are tons of intelligent animals already existing on earth simultaneously as humans, how common extrasolar planets are, and how Europa within our own solar system also shows the possibility of life existing elsewhere in our own solar system.
Most binaries are elliptical and cannot support stable orbits, a planet without a stable orbit will not have time to evolve life and will more then likely get sucked into a star or ejected from the system.
How eccentric are these elliptical stars? And their maximum separations? And what kind of binaries are these? The top 3% of mass O-G stars because they are the most easily seen (and the O-A stars not have enough time to evolve life anyways), or the more common K-M stars? (
Research has indicated that most binaries are O-G stars anyways, so most of the time you are dealing with K-M stars which are found as single stars)
No, how long a civilization will survive is exactly what it means, how long a civilization broadcasts is only relevant to SETI.
How long a civilization will survive is far longer than expected with the original Drake Equation. Should they survive the initial development of high energy technology, and spreads to multiple star systems, their lifetimes are virtually unbounded.
Really, can you explain an adequate mechanism for a civilization that has spread beyond a single solar system to be destroyed?
Asteroids or natural disasters can't destroy them, for they have spread to multiple systems, and are unlikely for both to suffer disasters to wipe them both out in quick succession.
Wars do not work at long distances at sub-light travel, as the defender is heavily favored, especially since there is no stealth in space, and the advancement of technology would enable the defender to almost always be technologically more advanced than the attacker.
The only reason we suspect there is a way to destroy a level III civilization is the Fermi Paradox. (it takes 10 million years for a civilization to fully colonize a galaxy assuming spreading outwards at .1% the speed of light; a blip in evolutionary scales) However, another solution is that they simply do not broadcast blindly for us to see (even we don't do that much anymore), have no interest in contacting us, ignored this planet because there are more profitable ones elsewhere, or simply philosophical reasons.
But is there anything inside of 100ly worth going too?
Meh, you've got to take first steps. Such as catalogue everything within 100 LY first, and then decide which are worth. Not decide which ones are worth going to first before looking.
Must not watch the news or keep up to date on whats going on on or little planet, because the outcome right now is definatly leaning towards destruction.
Cold war's over. We're not going to wipe ourselves out anytime in the foreseeable future.
What they are thinking right now is using lasers, not the Star, to power the sails.
I'm not entirely certain that would work.
If you stick the laser on the Earth, that's got to be a huge laser to span the distance. X-ray lasers and gamma ray lasers will be the only feasible option, and that is... Not the best choice. (too easy rotating the thing 180 and firing at a city...)
Sticking it on the spaceship is useless, because of conservation of momentum. The laser firing from the ship will produce a small reaction backwards, exactly canceled out by the momentum gained by the light hitting the sail. Unless if you want to point it in the other direction, but that's a photon rocket, not a solar sail.
Definatly, predator prey evolution also happens faster then say climate evolution, but you have to evolve just to get to predator prey. Also as I pointed out, complex animal life requires oxygen and with half the planet frozen and dark, and half the planet baked dry I doubt, even if the planet has a sufficient magnetic field, that the amount of vegetation that could possibly survive in the twilight zone would be enough to create a sufficient oxygen atmosphere.
Complex animal life does not *require* oxygen. Oxygen simply makes it the easiest.
Convection is enough to dispel vast temperature extremes. Just we need to know how much water is on there, continent placement, and/or how thick the atmosphere is to determine how well distributed the energy is.
The magnetic field would not be incredibly strong because of slowish rotation, but it should exist, and it should be stronger than Mercury's at the very least. We are more concerned about volcanism than the magnetic field for atmospheres anyways.
Could be possible, though why becomes a question, why would people want to stay in a ship for ever and ever with no end goal. Maybe some offshoot scientific community, but then whats the incentive for Earth to commit so much for such an endeavor... to build a ship to spread humanity to the stars is one thing, but to build a ship thats just going to cruise around forever.
