Infinity is fun :) It reminds me of that (totally wrong) quote in The Hitchhikers Guide To The Galaxy that the population of the universe is mathematically zero. The Universe is a very big thing that contains a great number of planets and a great number of beings. It is Everything. What we live in. All around us. The lot. Not nothing. It is quite difficult to actually define what the Universe means, but fortunately t…
I know this is not meant to be taken seriously, but some claims don't even make sense from a purely mathematical point of view. > Area: The area of the Universe is infinite. Right now there is more evidence for the universe to be finite rather than infinite. But apart from that: Just because it has no borders doesn't mean it is infinite. This is a classic failure in understanding infinity. For example, the area of th…
If you take a pragmatic stance and consider only what you can measure, then the observable universe is certainly limited. And the rest is, as you pointed out, a matter of semantics.
This part of the Hitchhikers' Guide might not have aged well, but because it contributed to that effect.
Out of which some 3 billion years had to pass before unicellular forms of life evolved into multicellulars. Who knows if this jump alone should be taken for granted - plus, not many planets could provide 3 billion years of "good weather" (or staying habitable) to start with.
That is the odd thing about the history of life on Earth isn't it? Prokaryote popped up almost as soon as was conceivably possible. And then. Nothing. For billions of years. The plausible explanation is that you need Oxygen for Eukaryotes and that's how long it to change the chemistry of a planet. It just seems weird to me.
"Let me make my position clear. The miracle, and I do not mean it in the religion sense, I mean it in the evolutionary sense, the miracle of the evolution, is the cell. While there are theories involving an RNA world and selforganising, it remains a mystery. Once you had the eukaryotic cell from the point of view of evolution and development it was downhill all the way, very very easy. "
I agree with you in that we will probably never have contact with another sentient species of extra terrestrial origin. The distances are to vast, the lifetimes of civilisations and even species too short and so on. However I do think that you vastly underestimate the probability of life. Take a look at https://en.wikipedia.org/wiki/Earliest_known_life_forms . See how quickly life appeared once the earth had cooled d…
But it's fairly likely to be carbon-based, as carbon is the simplest existing element with the maximum amount of valence electrons. And generally, simpler (= lower ordinal number) means more stable, as well as more likely to arise (as less energy is required, e.g. in stars).
Do you think the periodic table contains all the elements in the universe?
But if there can be no data about it. Does it even make sense to talk about it as existing? IIUC everything in the observable universe is sufficiently far away from anything else that any causal relationship with anything is either from before inflation or within the universe we can observe. And given how the existence of matter seems to be rather connected to time, it self a by product of interaction, it seems to fo…
That is an interesting metaphysical objection. Does a particle exist, if you cannot measure it? There is certainly no reason to think it does. But is there reason to categorically deny is existence? Very hypothetically, you might build a "Laplacian supercomputer" that could answer this question. But until this can be done (wich I doubt very much), the agnostic approach, to leave the question as undecidable, is pruden…
But what does it mean for a particle to be near the horizon? The horizon is ours, thus the particle must be near our horizon, which means either the horizon we might observe today, sans opaqueness of the initial universe this means a point in spacetime before particles even existed. Or the furthest point we might observe in the future, which means sending the observer at C in any direction. Now, would the observer ever reach a point where she’d be able to observe any trace of interaction with anything that wasn’t observable from earth at the start of the journey?
Let’s take a photon, or graviton, traveling towards the observer such that the observer would interact with at a distance from here expanding at C, that would be our particle “very very near the horizon”. It would never reach earth so strictly speaking it is outside our horizon so in a sense it is proof of existence outside the horizon. But let’s expand the definition of horizon to include all particles that could be measured by the observer, could any one of them have a history including an interaction with a particle originating outside this expanded horizon?
And some people still aren’t sure if there is other life beyond Earth. :) That's entire galaxies. Not just stars, and that's just the observable universe. We are still being surprised by the lifeforms we observe here on Earth, and the environments and conditions they can thrive in (including the outer hulls of our spacecraft), and we still have yet to discover and catalog all the life on our planet. Life may even com…
It makes me excited and happy to think of other life out there, waiting to meet us. But sad that I will probably not be around to witness it.
There's a huge difference between what evolved organisms can adapt to, and the conditions necessary to start life. Look, humans already adapted to being in space for prolonged periods of time. We adapted to every climate. But drop a naked human in a random spot on our planet, and he will die with high degree of probability. And that's after billions of years of evolution.
Just a reminder - we were naked for most of our history and were able to survive.
But not in nearly as many emvironments as we can today. We can assume, over time, life learns to live under absurd conditions; but its hardly safe to think it can start in those same conditions.
> And some people still aren’t sure if there is other life beyond Earth. :) Until we actually observe it, no, we can't be sure; the probability of it existing is high simply due to the sheer amount of dice rolls there are in the universe, but the likelihood of us observing it is low. We already know there is and was no intelligent life in our solar system besides what's on Earth; there's still hopes of finding traces…
That was my reaction as well. If you're being scientific about it, how can you be sure at all? We have observed exactly zero instances of life beyond Earth. We're all free to believe whatever we like. I have beliefs of my own, but I don't expect anyone to share them unless they happen to believe it too. I just hope people who are so sure of extraterrestrial life can comes to terms with the fact that they are making a…
If we ever create life from nothing, identify conditions where that would happen,estimate number of locations Galaxy that would have planets with said condition...surely that would provide scientifically informed estimation of extraterrestrial life.
>I also doubt humanity will find a way to travel fast enough to get to another solar system within a human lifespan. The next solar system is only four lightyears away. Given the will to break nuclear test ban treaties we think we could develop nuclear pulse propulsion drives that achieve about 10% the speed of light. Even after accounting for acceleration and deceleration that gets us there in a human lifespan. Gran…
A better strategy is to start mining asteroids. Sell mined stuff on earth to make enough money to build ships and lift necessary bootstrapping material out of the gravity well. Also plenty of water out there and sunshine, burning hydrogen as fuel should be possible. Now you will have enough machinery in space to mine building stuff and enough fuel. Gradually build permanent colonies in space. It won't get all humans…
Even if there were bars of pure gold just sitting there on asteroids (or even floating in orbit) for us to take, it would cost more to get them than just mining them on Earth. People underestimate the stupendous economic cost of doing anything in space.
> But all lifeforms That's not nessisarily true. Single celled organisms have a rather fluid exchange of genetic information even our 'single cells' are really several different organisms. It's possible life evolved many times on earth and current single celled organisms and thus all life has a mismatch of ancestors. Further, life may regularly evolve even today, but simply get eaten due to the stiff competition. PS:…
> It's possible life evolved many times on earth It's also possible it evolved elsewhere and rode here on a meteor - or was brought here by some other lifeform several orders of magnitude more advanced than us, using earth as their own cosmic terrarium.
Why not both. We could also be descendants of an invasive alien species that killed off all of Earth's native lifeforms.
It's good practice to assume the simplest possible solution. However, the full range of the full range of what might have happened is ridiculously large.
I'm tired of hearing these types of extremely confident lay-assertions about life beyond earth. It's true that the number of planets is incomprehensibly large, but it could also be true that the probability of a particular planet developing life is incomprehensibly small. In physics and chemistry, there are some odds that remain so extremely small even when you roll the dice many many times. Stop using "incomprehensi…
Let’s talk numbers. There’s 250 billion stars in our Milky Way galaxy. Our local supercluster has 100,000 galaxies in it. Previous estimates were that there are 100-200 Billion galaxies in the observable universe and this article suggests the figure is 10x as much as that. The Kepler telescope has been discovering planets around nearby stars for a while now, and the impression we get are that at least half of the sta…
Nice intuition. Too bad intuition has nothing to do with quantifiable numbers. "Extremely remote probability" is a human idea that you have in your head. It has nothing remotely scientific in it.
There's an extremely remote probability that the atoms in your body might teleport to the Great Wall of China. How much are you willing to bet that it happens?