Bluemofia
F=ma
Citation please. (Complex life impossible without oxygen)
You are assuming that early Earth has the potential to experiment with all the other the sub-optimal chemical systems other than oxygen.
An example is the use of Sulfur as an oxidizing agent, instead of Oxygen. Species of bacteria on Earth do that already; they convert H2S to H2SO4, and another uses H2SO4 much like we use Oxygen. They are inefficient compared to Oxygen, yes. But also note that we have relatively little Sulfur.
Therefore, it becomes impossible to do so on a large scale on Earth due to abundances of Sulfur, not because it is impossible to develop life based on it because it is too inefficient. Your conclusion was correct that alternate biochemistry life is not likely to develop, but for the wrong reasons.
This being said, Oxygen is the most efficient, yes. And also the easiest to form complex life with. However, Oxygen also isn't this light whispy molecule that cannot be held onto without strong magnetic fields to keep out solar wind (which I will do math a few lines down to show you why)
A post ago you were concerned about how long they survived, not how long their radio waves broadcast. If that is the case, we are nearing the end of our lifetimes ourselves because we don't wantonly broadcast Radio as much, and use more precise methods now.
Regardless, one intelligent species per million stars is awfully low in my opinion.
Well, seeing as you use the fact that we haven't detected any civilizations to state that they cannot spread beyond their home system is pretty much ignoring the far more likely options...Well my point is that a civilization cant spread beyond thier home system so your point is moot
Not all intelligent life must operate on a human mentality and scales. We only got our mentality by inheriting whatever we evolved from. Had we evolved from something else, we would have a far different thought process and physical attributes.
A 100 year journey might be trivial for a particularly long lived species, and they will not mind the trip at all. Or a species which works very well in societies, and a generation ship might be extremely favorable. Etc. Etc.
What is stopping those from leaving? All it takes is 10 million years to fully colonize the galaxy. Just saying "you can't" is far less likely considering how there are no physics preventing it from doing so.
All orbits are mostly* elliptical. Circles are a special form of ellipses where the eccentricity is zero. How eccentric is elliptical is a very important question, for it determines how much of a deviation from circular they are. The maximum separation distance is also very important. If the maximum separation distance is very small, the eccentricity matters not, for you just orbit far out compared to the separation (which could even be as small as a single AU) and you are in a stable orbit.
Also, most stars are single stars as shown to you in the article I linked to in the last post. Most luminous (and short lived) stars are binary. The sun is an average star by range of mass, but the top 3% by number of stars. The vast majority of the stars are single, red dwarf stars.
*I said mostly, because when there are multiple objects, they affect each other and cause it to become non-elliptical slightly.
So yes. *Technically*, any binary with a non-elliptical orbit can, and must support planets (or a third companion star, but those aren't binaries). But how precise we can measure the deviation from elliptical orbits is another question.
CO2 is roughly 50% more massive than O2. The molecules are at twice the energy because of its temperature (in K) roughly double earth's. Kinetic energy is 1/2mV^2, so thus velocity of the CO2 is Sqrt(3)-Sqrt(2) percent higher. Or, roughly 32% greater velocity than Earth's O2 molecules.
32% faster moving molecules, at a slightly smaller escape velocity, and yet it still has an incredibly dense atmosphere, combined with the solar winds being twice as strong (distance to sun is .7 AU, so by surface area of a sphere being (4*Pi*R(Earth)^2)/(4*Pi*R(Venus)^2), you get roughly twice the flux of solar wind than earth), Venus should have lost all of its atmosphere were it not for volcanism replenishing it.
Magnetic fields are less important than volcanism for an atmosphere.
I'm not sure what you mean by your first comment, but from what I understand, you have it backwards... You are looking at Earth, and then saying everything about Earth that makes it different from the other planets is a requirement for life. It's much like taking a millionaire from Germany and a poor person from France and saying that to be rich you must speak German. (Oh, and the Gas Giants have a *very* strong magnetic field. A combination of the Metallic Hydrogen core, and the fast spin rates)
Anyways, you could go look up what is causing the magnetic field rather than speculate... You got it correct that you need a liquid core, but for the wrong reasons. (and it must allow free flowing charges; a fresh water core cannot generate a magnetic field. This is why we know Europa's oceans are salty)
The tidal effects on the moon to the Earth are not the primary forces responsible for a liquid outer core. Tidal effects only play a major role in heating when the object is in a fairly elliptical orbit. It is the radioactivity decay combined with being earth mass. Outer space is a very good insulator, BTW because there is no convection. Only radiation, which depends on surface area (spheres are minimized surface areas, and they have large volumes) and temperature.
Mind you, the primary reason why Venus has a molten core is because of its mass, not because of its inability to lose heat. (its interior cools off fine. 500 C is not enough to melt rocks, and there is still a temperature gradient.) And Venus has no magnetic field. Or at least one that is so weak, that the effect of the Sun's magnetic field interacting with the planet to create an induced one (much like sticking a magnet to a piece of iron causes it to have a magnetic field) is stronger than Venus' intrinsic magnetic field.
Are you kidding me? Antarctica is not hours away from being safety. Neither is Siberia, most of the Sahara, most of the oceans, etc. Earth is very hostile to human life without technology. You plant a man in Scandinavia without technology (tools, clothing, transportation, etc.), and the vast majority of the time he dies. That lucky coincidence that he happens to find a cave may prolong his existence for a few hours, but without technology, they are going to die very quickly.
Why must you demand exploring space to be done without technology, when you can't even survive on the majority of Earth without technology? Space stations exist. They exist in a void of space. Now take that same rigor of construction, and put it on a planet. Some things can be shifted around, but fundamentally keep the airtight construction. Are you trying to say a human cannot survive in those conditions?
On that, why must you breathe the atmosphere? It's like saying fish cannot live away from a lake because they cannot breathe the atmosphere, and fish tanks shouldn't even be considered. Therefore pet goldfish living away from natural bodies of water should not ever be considered as a possibility.
Stop using Earth life as an arbiter on what all life should be.
Even then there are plants on Earth that grow best in shade, and actually do poorly in direct light, with the direct light raising the temperature too much and promoting too much evaporation for the plants to retain their water.
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You do know that this is average temperature, not energy per time, right?
Also, this is the majority of Earth life that hates the cold (developing in non-cold environments), not all life hates cold. There exist bacteria that can only survive in sub-zero temperatures, and die if the temperature is brought a few degrees above zero.
Heat certainly helps chemical reactions, but too much of it and your proteins get bent out of shape. Life is optimized to its environment, not the environment is optimized for life.
Ocean currents distribute heat very efficiently. Water at the North Pole in winter is only -2 degrees at its coldest, near the surface, despite being in 6 months of winter (the water further down is at around 2 or 3 degrees). Meanwhile, the equator goes up to 30 degrees. What's more important, is that there are currents which bring the warm water and cool water around, so you often find warm water in weird places, such as Britain, and cool water in odd places, such as the Galapagos.
Normally, currents play a far larger role in moving heat away from heat gradients. Even then, the evaporated water does not hang around the same spot when there is a concentration gradient to flow down. The evaporated water would move off to cooler regions (twilight zones) and condense into clouds, and continue onwards to the colder regions, releasing energy as they continue to cool. The energy would cause the surroundings to heat up, and also the clouds at the dark side will act as insulation there, further distributing the energy properly.
The two combined will most likely do a very good job at mediating the temperature differences of the planet that you might not even have any permanent ice except at the very opposite side. However, it remains to be seen just how much water, and what the continent placement is before how well distributed the temperature can be determined.
All species must go spacefaring or extinct. Therefore, it is imperative we develop spacefaring technology, and identify potential places to live.
Just because you believe we can't go there, doesn't mean we actually can't. Let the Engineers and Physicists work on whether or not we can or can't go, not the politicians.
And it's not like every telescope is trained on the heavens for extrasolar planets. Some physically cannot see them no matter how hard you tried, and those are used for other ventures. The large ones that are "powerful enough" usually can't be used for searching close things. The objects are either too bright and may damage the instruments, inefficient use of resources, or not enough funding.
It is easier to get funding to detect extrasolar planets than it is for asteroids, partially because extrasolar planets are new and exciting and everyone wants to be one of the main players in it, and partially because people are more interested in it. More people work in a McDonalds than work at detecting NEOs world wide. It's exactly the same type of argument that gets billions spent in a war that gets us nowhere as opposed to feeding starving children in Africa (hate to be cliche about it).
Also, just because something has no immediate "use", it isn't useless. It itself can serve as inspiration to promote new people going into the field. Sputnik and the Space Race most likely has inspired many people to become scientists and engineers. The greatest of discoveries are ones which have no real purpose to them. The Cathode Ray Tube was conceived as a toy, and nothing more when it was first invented.
Another point is the law of diminishing returns. What new discoveries can you gleam from searching the inner solar system over and over again? A few hundred more asteroids/meteors a year, slowly diminishing until it asymptotes out. Why not use the same resources to apply it to an undiscovered area, and quickly make huge strides in discoveries, while the better known places can continue to refine themselves at their own pace.
As a side note, that is almost exactly the same reasoning the most technologically advanced nation (China) was passed up by Europe. "Exploring other places may be fascinating, but it has no applications to the nation. Best concentrate on developing our own country than worry about outsiders who will potentially destabilize the country." Or something similar under those lines.
If you are feeling nostalgic and want to play again google "Ur-Quan Masters."
