How Long Was Venus Habitable?
eos.org
eos.org
1. Venus is easier to reach than Mars. The Delta-V is 0.4km/s and 0.7km/s respectively [1];
2. Mars has practically no atmosphere and really low gravity. It's really not that much better than colonizing the Moon but a whole lot further away [2].
3. You wouldn't live on surface of Venus, at least not initially. You'd live in the atmosphere [3].
4. Energy will be plentiful on Venus, far more than on Mars or even the Earth, just from solar energy. [4]
5. Venus has nearly Earthlike gravity.
So it's actually not as crazy as you might think and shouldn't be immediately dismissed.
[1]: https://space.stackexchange.com/questions/2156/does-a-missio...
[2]: https://qz.com/1105031/should-humans-colonize-mars-or-the-mo...
[3]: https://www.youtube.com/watch?v=BI-old7YI4I
[4]: https://www.extremetech.com/extreme/196114-nasa-is-developin...
I'm not sure where those numbers are coming from. The Δv for reaching low earth orbit is already on the order of 10 km/s.
That said, looking at that wikipedia page these numbers don't match up with any kind of LEO-mars or LEO-venus transfer. Numbers seem to be off by an order of magnitude.
https://en.wikipedia.org/wiki/Delta-v_budget
But no matter how you slice it, Venus is easier to get to than Mars, if for no other reason than that aerobraking is a lot easier when your destination has a thick atmosphere so you don't have to carry as much propellant for orbit insertion.
https://mars.nasa.gov/mro/mission/timeline/mtmoi/
https://www.space.com/2439-tricky-task-aerobraking-mars.html
The reason is that you can do lowering incrementally across multiple orbits, but insertion requires a huge delta-V on a single pass. It might be possible in principle, but the engineering challenges are daunting. I don't believe it has ever been attempted.
It is not used for insertion of orbiters because strapping some rockets to them is easier/lighter than the heat shields and other equipment that would be needed for braking. They would also have to retract solar panels and do a bunch of other things. The martian atmosphere is more than thick enough to handle the ~1km/s for insertion. All the landers shed more than that (3km/s) on entry from orbit, a maneuver that only uses 1/2 the braking potential of the atmosphere.
Here are some more details:
https://space.stackexchange.com/questions/37250/is-aerobraki...
Turns out there's a distinction between aerocapture (which is possible but has never been done) and aerobraking (which has been done but it not common).
https://en.wikipedia.org/wiki/Aerocapture
So I guess I have to concede that my original claim about Venus being easier to attain because of its atmosphere was probably wrong.
Think the scene from "2010: The Year We Made Contact" where very large spacecraft aerocaptures in Jupiter's atmosphere. That probably wouldn't be possible at mars, not without hitting the ground. Or 'Independence Day'. Those giant spacecraft arriving at earth surrounded by fire could not possibly have aerocaptured/braked in earth's atmosphere.
Really, if you are already in space with all that infrastructure, and economy needed to support settlement on another terrestial body, you would have to already have at least few megalopolises in the orbit.
In order to make anything in a space station, you have to bring something from outside. Not so on a planet.
So you may make an investment - spend initially to make a planet base, then enjoy smaller expenses.
Maybe the question is of comparison - how big space infrastructure one need to colonize the planet comparing to returns from planet base. Is it obvious that planet returns are smaller?
This is getting off the rails into of science fiction I guess, but it raises the question of how do you transfer the "you" into the new brain? That way you could destroy the body or let it die and still have continuity. It's not clear that merely making a "bit-for-bit" copy is enough.
There's no loss for the rest of the world. What if actual sleep is analogous to that? The you that wakes in the morning is a fresh copy with memories up until you 'died' last night.
Definitely digressing into sci-fi thought experiments.
the robot wouldn't, you'd be dead
Yeah this is the big question: what constitutes as "you"?
Your body? You can lose a limb or parts of your brain and still remain "you". Your memories? they are constantly re-forming with people forgetting things and new memories being made. Your way of thinking? Neurons are extremely long lived cells.
Unless you believe in souls (which many religions do), the experience of "you" is entirely defined by the matter of your body and maybe your surroundings.
Let's assume we can build machines that can fully emulate human minds. Let's assume this emulation is good enough to also emulate the self-ness experience we are interested in.
Your question was (and the question of LoSboccacc), that if you have this technology, can you somehow transfer the self-ness so that the real, legitimate, "you" gets there, and not a copy? How do you know it's really you?
I'd argue that consciousness and self-ness is weirder than humans usually experience it: it can do more things than you'd think.
Let's take Bob, someone born in the simulation, that is, he has spent his entire life being simulated in silicon. For all purposes, his self-ness is the only true legitimate one. There is no difference in legitimacy between his simulation and a human in flesh and blood. That's just a simple conclusion of the basic assumption that there are machines that can do this.
Now if we have such a machine, then it runs some kind of program that can at least store Bob's state as a finite set of bytes. Whether it's a petabyte (less likely) or a yottabyte (maybe) is less relevant, what's more important is that it's a set of bytes.
Now you can do interesting things with this data. What happens if you pause the emulation, save the data to disk, and then decide to either a) stop the emulation and load it from the saved state or b) delete the saved copy and resume the emulation. In both scenarios a and b you'd resume with the same state for Bob as in a) you load the same data you just stored and in b) you just create a disk backup and delete it. Nothing would really change. It would be the same Bob afterwards in both scenarios.
In the next experiment, you save it to disk, turn off the emulating computer for a day, then turn it on, loading the disk again? It would be the same Bob, right?
Let's combine the two experiments. Let's pause the emulation, save the data to disk, and then decide whether to either a) turn off the computer for a day or b) resume the emulation and run it for a day. After the day concluded we power cycle the computer and load the data we stored to disk yesterday. Now my argument is that it's still the same Bob in both scenarios. Scenario a) is our second experiment. As for scenario b), at the point of the pausing, we haven't decided yet about whether to choose a) or b). So clearly, the Bob stored on disk must be the legitimate one, otherwise a) would end up "killing" Bob. So it follows that in scenario b) it's the same Bob as well.
Next I'd argue that whether there is a decision or not isn't really relevant for which data is being stored. It'd be the same Bob if you always chose b). In the fourth experiment, you'd just always go with b).
If we apply this thought experiment to the boundary between emulated and incarnated minds, the conclusion to be drawn is that the cloud copy is always [1] legitimate, whether the original host dies during the copy, after the copy, or not at all.
This conclusion is a bit humbling and it's understandable that people are critical, in fact I'm myself. But I believe this is just because the way we experience life on earth as separate individuals and consciousnesses, simply because our bodies are made like that. Our perception of what a consciousness is is blinded by the fact that each human starts with a blank set of memories and has their own way of deciding things, own skills etc. But once we get the ability to copy entire brains, those new experiences with consciousnesses in our society will fold the perceptions of individuals. Of course there will always be people who still believe in souls, and maybe there are in fact souls we just don't have the detection technology for. But 100 years ago people were superstitious of being photographed as they'd think you are stealing their soul. Maybe in 100 years we'll think that the old kind of thinking about consciousness is the same kind of superstition.
I'd say it's an artifact of our self-preservation drive. Of course it's very important to quality control whether the simulation is really doing what's promised.
To conclude, I think it's much easier to believe in life after death if you've seen your friends and family do it before your own eyes. Even Thomas ended up believing!
Uhh the comment has gotten a bit longer than I anticipated.
[1]: Note that this opens the question: can you just make any kind of copy and call it legitimate? Of course not. Consciousnesses are even weirder. The transition between legitimate and illegitimate is fluid. I'd consider someone who had a stroke and can't talk or walk any more as a weakly legitimate copy of the person pre-stroke. My argument assumes legitimate copies, but of course people can have different opinions/standards on what constitutes a legitimate copy. The question will become especially interesting if billionaires will get access to different copying methods than poor people.
I'll see myself out
http://seanwilliams.com/words/books/sci-fi/the-resurrected-m...
We're well out of the realm of science into science fiction, but I feel it's a valid question to ask - all of our consciousnesses have developed in ape bodies adapted for the savanna, with a bunch of survival related traits and sub-processes.
If we remove our "selves" from our bodies, are we still us?
We are not the individual cells of our body because most of them will be replaced in the next weeks/months/years. We also don't think of any body with a knee replacement as any less human. Even altering the genetic code of a huge part of your body, like after stem cell transplantation, is not commonly seen as making us less us.
Also suppose it was possible to build a synthentic neuron that behaved just like the ones inside your brain. If you started replacing your neurons with the synthetic ones, no individual neuron would "change" you. So were would you draw the line? At 10% synthetic neurons? At 20%? At 100%?
If we see ourselves as biological beings another interesting point is how you would view a 1:1 copy of yourself. If we constructed a synthetic human that had the exact same number of molecules in the exact same place as you, would that human be you? (Leaving aside that that's basically impossible, just as a thought experiment)
If you answered the last question with "no", that would also mean that not even the way we process information and think makes us us, since the 1:1 molecular clone would behave exactly the same as you in the same environment (in a purely deterministic universe at least, leaving aside probability and Heisenberg's uncertainty principle).
So are we instead an uninterrupted instance of a thinking process? That would allow us to differentiate us from the exact clone. However in that case, would you be another person after being unconsciousness? What about general anesthesia? This really keeps me up at night.
It's next to impossible to define what we are and that we think of us as independent, unique beings might just be an illusion.
Why? You're pretty close to the right answer:
> are we instead an uninterrupted instance of a thinking process?
No, for the reasons you described. What we are is thinking-processes with a coherent series of more-or-less-uninterrupted links to the past. When you undergo general anesthesia you wake up as the same person because you can remember who you were before anesthesia, and you feel and act like that person.
The interesting case is not anesthesia (or sleep) but amnesia and traumatic brain injury or mental illness that changes your personality.
But of course the conditions you mention are also very interesting and make it non-trivial to define the "true" essence of the person. Another interesting one would be dementia.
That's right. Why is that a problem?
Imagine you had this done to you, and imagine that in order to clone your brain you have to be put under anesthesia (because the process takes time and you need to capture a coherent snapshot). When you wake up, how are you going to tell whether you are the clone or the original?
As far as I’m concerned we might very well be just processes that can in theory be copied and recreated. In that case the person in the thought experiment would exist twice at a single point in time and then diverge into to different persons due to different environments and probabilistic processes in the body.
that being:
> If we remove our "selves" from our bodies, are we still us?
But answering this is now a straightforward thought experiment. You just approach it incrementally.
If you replace your limbs with prosthetics, are you still you?
If you get a heart-lung transplant, are you still you?
If you get an artificial heart, are you still you?
etc.
> a somehow unique, identifiable self which ... is how most people view themselves
Well, yeah, but that's a limit of our present technology, not necessarily a fundamental aspect of what it means to be human. Technology redefines the answer to that question all the time.
This already happens, though before the formation of any memories. We call them identical twins.
The divergence is more limited than you might imagine. One striking experiment found that if you separate identical twins and give them the instructions "just draw whatever comes into your head", they are likely to draw the same things.
For what it’s worth, I think that in the process of gradual replacement of human organs with their “mechanical” equivalents, the brain will not be the last one to be replaced.
I think the free will lectures from John Conway also go in that direction: because some properties cannot be predetermined, free will must exist. Something must make a decision in order to have an outcome.
This all goes far over my head and I may have misinterpreted the great John Conway. In that case I beg your pardon and would love to hear your thoughts on it.
In the great scheme of things, making environments safe for human levels of tolerance is extremely wasteful. You need the right atmosphere, temperature, radiation freedom, freedom of toxic materials (and guess what, many chemical processes create tons of them), noise freedom, etc. This causes huge costs already now because industrial processes need to be engineered in ways to reduce emissions, it makes nuclear energy unavailable, people not wanting to live near airports, etc.
Even gravity is an extremely wasteful thing. In order to have it, you need a giant planet full of precious construction material for dyson spheres, anything->iron fusion/fission reactors and hawking radiation matter->energy converters, all unavailable because some individuals chose to colonize the surface of it...
The optimal approach for intelligent life is to architect computers that can run in the vacuum of space with minimal shielding and then deploy them across the galaxy to convert the available energy into intelligent thoughts and experiences. What the computers will run is up to us.
Adtech and cryptocurrency mining?
Our bodies (and culture & environment) are part of our minds. They cannot be separated without destroying that mind. Also, most of what we think is our own “intelligence” actually exists outside our brains, in our culture & civilization.
“Uploading our minds” only seems plausible if you have a cargo cult understanding of what is actually happening.
You make my point, we are not just our mind, but a mind dynamically interconnected with a civilization in amazingly complex ways. Whether its the medieval catholic church, the interstate highway system, WoW, or the Internet.
Cognition scientists are pretty sure that we think with our bodies, not just our brain. If you totally separated the human body from the human mind, it is by definition not a human anymore. At best it would be closer to the ghost we leave behind online after we die. Just a shadow or footprints. I dont expect us to ever do better than making really convincing animatronic ghosts.
Titan is not oversized, in comparisson to Saturn. It's a normal, larger-than-Selene (Earths moon, but not that much larger really). Compared to Mercury, it is larger in radius, but less massive (about 1/3rd the mass). Now let's look a bit at Selene. It's an "oversized moon" at a bit more than 1% our planets mass. If that was the criteria for oversized moons, then Saturn would require an Earth-like planet orbiting around it to be considered to have an "oversized moon".
Another thing to consider: if we're thinking 1% mass as the parameter, it would've required a far larger moon to crash (from a retrograde orbit) to change Venus's rotation from prograde to retrograde.
Now on to Triton... it didn't form with Neptune. It's suspected of being a Kuiper Belt Object captured by Neptune that will eventually disintegrate from tidal forces once its retrograde orbit gets it close enough to the planet. If it had been formed 4 billion years ago with the planet, that would've already happened.
All in all, I'm not a astronomer nor planetary scientist, just a software engineer who really likes astronomy and got a few math and physics class at uni. But this "twin planets with oversized moons" theory has very little substance.
Octopus.
https://qz.com/1281064/a-controversial-study-has-a-new-spin-...
I’d suggest reading his work anyway; as a kid I stumbled upon something he wrote and enjoyed it, even recognizing it was bogus.
Mars can't even retain water vapor.
The good news is that we can use the parasol to funnel hydrogen from the solar wind back to Venus.
Oh, wait, we can't even work together as humanity to contain a virus.
I am not a climate scientist but I’d imagine there would be significant changes to rainfall patterns over most of Europe, Africa, and the Middle East
Edit - sorry, reply was meant to be to parent
[1] https://www.nasa.gov/content/goddard/nasa-satellite-reveals-...
https://www.theatlantic.com/science/archive/2017/03/its-now-...
There is a theory that American reforestation was responsible for the Little Ice Age.
https://arstechnica.com/science/2018/09/carpeting-sahara-wit...
And BTW our species is conducting its largest peaceful "mobilization" ever to deal with this virus; it's actually quite inspiring.
This is a funny way to phrase the causation. The state of the Sahara is surely not exogenous -- the transition must be caused by the climate. (It can then contribute further, but why attribute the changes to an intermediary effect?)
Please do not do this :).
Deserts are great for shedding heat into space (highly reflective in the visible, highly emissive in the infrared, low moisture in the atmosphere).
We had a theory (not yet published, so take it with a grain of salt) that desertification might buffer the radiative forcing effects of CO2. Unfortunately, when we analyzed the last 20 years of satellite data, the opposite is happening--people have been watering the desert like crazy, leading to a net reduction on the order of ~100-200,000km^2.
If you blocked all incoming sunlight, how long would it take for the surface to cool to human-tolerable temperatures?
Or more extreme, how long would it take to cool it down to the freezing point of CO2, then build some sort of maglev launch system and lob solid CO2 to... Mars maybe, that planet could use more atmosphere.
And how much stuff would you need to launch to spin up Venus? Months long nights are not fun. Can you launch stuff to yield more spin, then have it sling around Earth or Mercury, and then have it hit Venus again, resulting in more spin up, i.e. getting twice the rotational acceleration from a launch?
I mean, how do you build a habitat capable of keeping humans alive when it’s 400 degrees outside?
Without a magnetic field (which could be built easier than terraforming), over 100 million years, it can slowly lose atmosphere, but nothing like a relevant rate for humans. The sun is also getting significantly hotter on a similar timescale, which makes habitation on Venus (And Earth, for that matter) significantly harder and dependent on active geoengineering methods.
At current temperatures it evaporates before it gets to the ground, so who knows when it gets cooler
Don't want humans to be around on Mars when that happens.
It's small enough that we'll be able to move it (if we haven't mined it apart by then).
For mars, You could crash nitrogenous asteroids into the surface, make GHG production facilities that emit CFCs or HFCs, and hopefully soil carbon gets released in a runaway effect. Thermonuclear weapons over the pole is impractical but a fun idea.
For venus, it's so tough, you'd have to block solar radiation and then fix the massive amounts of carbon with co2 capture... maybe if we develop co2 capture for dirt cheap on earth, we could make sky cities with carbon fixers on venus, after a few hundred years it'd be colder...
Fun to think of, but ultimately we need to terraform earth towards cooling, as our current warming is too successful
If I were a very determined, ultimate Bond villain* who set out to destroy the whole universe, what are my options? How bad can I fuck it up for all ? Back-to-back mega nuclear explosions occurring simultaneously on all planets within reach? Could that start chain reactions around our galaxy that'd bring it all down? What else?
* Funnily enough, I just started reading 'From Russia with Love' whose first few chapters deal with the unusually vicious nature of our henchman.
The way to settle Venus is in balloons floating in the atmosphere, at altitudes with decent temperature and pressure.
It would be a great opportunity to one day build a strip mining colony on Venus, and ship those metals to Earth, and build future space colonies. But it might be easier to find some random floating asteroids that contain all those valuable metals.
I think the most important ingredient that Venus does have, is gravity, that’s near similar to Earth. This means that humans can live on the ground, and not be subjected to mass and bone deterioration of living on Mars.
But first, we’ll need to solve some engineering problems, like how to cool the place down. Maybe throw up some solar shades, and harvest the sun.