How unique is 'Earth-like' life in the universe?

Discussion in 'Science' started by Medieval Man, Nov 5, 2017.

  1. Nightmare515

    Nightmare515 Ragin' Cajun Staff Member Past Donor

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    I remember it quite comically because my sister called me freaking out because shes one of those people who believes in everything. I'm talking literally everything, bigfoot, abominable snowman, loch ness monster, aliens, ghosts, demons, zombies, Hellraiser, and whatever else you could even think of. So she calls me screaming bloody murder because Independence Day was happening in real life apparently and she was convinced that out of all the folks in the world they had come specifically for her lol....

    Watching that unfold in real life was hilarious. Folks were rushing to the stores and emptying the shelves and everything. Neighbors were inside calling loved ones. Weirdos were on their roofs with signs and all types of **** lol. Meanwhile my neighbor who is also a big Astronomy guy and myself just walked outside stared at them for a few mins then went inside and sat on the couch.

    Human beings have some pretty extensive imaginations to say the least. Which is funny to me because you would think behind the hysteria some logic would prevail. Seeing how these mysterious flying orbs flew around for like 3 hours you would think that if it was something out of the ordinary then the US Air Force who has a fully operational base in Phoenix would have probably scrambled some jets over there to take a look at it.

    The Air Force will scramble fighters to intercept you if you accidentally fly your Cessna too close to their base or training area. I'm pretty sure they would have launched some fighter jets after a formation of alien spaceships flying around Phoenix for 3 hours scaring the crap out of everybody lol.
     
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  2. OldManOnFire

    OldManOnFire Well-Known Member

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    If Earthlings were to ever travel to another solar system, or ET's traveling to Earth, is it fathomable to achieve this in small spacecraft (2-3 people) or spacecraft the size of a small city (100's of people)? I'm guessing it will require an entirely self-sustaining biosphere capable of multigenerational travel. Therefore, unless it can dock outside of a solar system, and be undetectable, it is unlikely they can exist without us fully knowing they are ET's.

    I can imagine this type of ET craft because it's actually something Earthlings could build today. The ONLY problem is there's not enough money on Earth to fund such a venture! I think the idea of ET spacecraft on small scale that can keep up with one of our military jets is not likely...
     
  3. FreshAir

    FreshAir Well-Known Member Past Donor

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    the real question is how long does human like life last on a planet before it destroys itself, what percent avoids that destruction....
     
  4. OldManOnFire

    OldManOnFire Well-Known Member

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    You're going to get your answer regarding Earth...soon...
     
  5. Nightmare515

    Nightmare515 Ragin' Cajun Staff Member Past Donor

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    Given current technology and even proposed technology it's not really fathomable for humans to conduct interstellar travel in anything but huge generation ships. As of right now we have no technology capable of reaching even the nearest star in anything less than literally thousands of years. There are a few theoretical propulsion systems on the table being researched that could cut that time down significantly, fusion drives, ramjet's, laser sails, etc. These theorized systems could propel a spacecraft to Alpha Centauri between 10-50 years or so, but the energy requirements are astronomical (pun intended), and they are still just theories.

    Here's the basic breakdown of how this works. Thrust requires fuel, more thrust requires more fuel, accelerating a huge sci-fi sized spaceship to the speeds necessary to get anywhere in a reasonable amount of time (a decent fraction of the speed of light) would require a lot of fuel. One of the biggest problems facing scientists and engineers is figuring out how to take that much fuel with you. So you build a huge spaceship weighing thousands or hundreds of thousands of tons, then you need fuel to move it, to move something that massive you need hundreds of times more fuel in weight than the spaceship itself, which makes the whole thing even more massive requiring even more fuel to move it.

    Think of it this way, the Alcubierre Drive (warp drive) is theoretically possible to build within the laws of physics. Sort of....but in order to power that thing to "warp speeds" to get to the nearest star in 4 years you would have to build a huge spaceship....and take the entire planet of Jupiter with you as fuel to power the engines.

    It's not just the money that's the problem it's our current limited technology. We basically just don't know how to build engines that can propel anything very fast yet. We're getting there though. ET may not be limited by our own technological handicaps though, they may very well have figured out how to achieve Star Trek levels of speed at like 1000x the speed of light or something and can zip around the galaxy in days or weeks. So them having a small 2 or 3 person spacecraft that can visit Earth as routinely as quickly as I can fly from New York to LA in a commercial jet isn't out of the question. We simply don't know what they can do, if they even exist, we've never met them before.
     
  6. tecoyah

    tecoyah Well-Known Member

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    It should be obvious to anyone who seriously contemplates these issues that interstellar travel is unlikely to involve organic entities of any kind. Likely even we have been investigated by micro probe and do not even know it, which is how they intended it. Considering the advances we little humans have made in nano technology I find it extremely doubtful that an alien would build a big spacecraft and fly around here at night with its lights on...what the hell would it need those lights for anyway?
    By the time WE decide to check out our nearest star it will likely be with a tiny little probe the size of a bumblebee that gets there in a decade or less and any images take longer to get here than it took to get there.
     
  7. Durandal

    Durandal Well-Known Member Past Donor

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    That's forward thinking! However....

    I think that macroscopic life is much less common than microscopic life, and that anything resembling tetrapods or other animals is less common still, especially when you factor in time. While other life might arise that bears some resemblance to terrestrial animal life, it may happen at such a distance and such a difference in time (star systems are still being born even as ours is middle-aged and we sit here contemplating the universe, while others are long dead) that we would be lucky indeed even to coexist. I mean, it's freaky to think about just how short a time humans in particular have been around, and just how briefly we have had the technology to study the cosmos in a meaningful way. The next civilization could be not only hundreds, thousands, millions of light years away, but as many earth years separated as well.

    So, have we ever been observed by other intelligent life? Ever been visited by a probe of any kind? Chances are, no way, Jose.
     
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  8. tecoyah

    tecoyah Well-Known Member

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    I like the beach analogy:

    Imagine a beach full of sand as big as the Earth. Now paint one hundred grains of sand neon blue. Take these grains and spread them randomly across the beach. Find one of these grains in a day with just your eyes and hands. keep in mind the waves are coming in and the sand is twenty feet deep. Oh..... and the paint will wash off in an hour,
     
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  9. OldManOnFire

    OldManOnFire Well-Known Member

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    We don't have the technology to go super-fast and maybe never will but we can go 50K/60K mph which means if we set out on a course towards Alpha Centauri it's going to be a very, very, very long time which is fine as long as the ship can sustain it's crew.

    When people talk about traveling at or near the SOL I can't help but think about the movie Spaceballs when they need to go fast and choose Ludicrous Speed...the people in the ship must deal with the acceleration and braking from SOL. How long will it take to accelerate without compromising the passengers to near SOL? How is it possible to navigate objects when traveling near SOL? How long does it take to go from SOL to 50K mph speed? Never mind the physiological effects on humans traveling at high speeds...just consider the acceleration and braking. Unless we discover new physics or whatever I just don't see an 'object' and it's passengers being able to travel at near SOL...
     
  10. Nightmare515

    Nightmare515 Ragin' Cajun Staff Member Past Donor

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    Going 50/60k mph is nowhere near "fast" when talking about interstellar distances. Just doing quick math it would take a spaceship around 50,000 years going 60,000mph to travel to Alpha Centauri...

    It sounds fast to us here on Earth, but not when your destination is roughly 25,000,000,000,000 miles away.

    You're talking about building a "generation ship" where the "generation" that actually arrived at Alpha Centauri would be well over 500 generations away from the ones who started off. Star Trek was supposedly set in the 2300's. This ship would arrive there in the year 52017 lol. We need to go WAY faster than that.

    What you are talking about is actually a pretty interesting discussion that is very real in the space industry. Think of it this way. Lets say we can somehow build the generation ship you mentioned and somehow it would actually be able to keep 500+ generations of humans alive on it for the next 50,000 years and it travels at 60,000mph and we launch it in 2020. Then 20 years later we develop faster engines that can go twice as fast and travel at 120,000mph and we launch that one to Alpha Centauri. Those folks who launched after the first ones zip right by them and get there twice as fast. Then 200 years later we develop super engines that can travel at 25% the speed of light and we launch that ship in 2240 and it can get to Alpha Centauri in 20 years. It gets to Alpha Centauri before the first ship even gets 1/10000th of the way there. Then we develop even faster engines that can go 50% light speed and launch those and they can get to Alpha Centauri in 10 years. Etc, etc.

    So the original "generation ship" we sent off to colonize the stars will arrive at it's destination about 47,720 years after the first humans actually got there and likely see a full blown Terraformed Alpha Centauri solar system with billions of humans all over the place. Pretty much negating their purpose for showing up.

    Point is technology moves too fast. In layman's terms, before we launch anything to the stars we have to get to the technological point of propulsion advancements to where the next thing we launch to the stars isn't going to beat the first thing we launched to the stars there.

    The fastest thing humans have ever launched into space was the New Horizons probe which travels at over 36,000mph. If it were pointed at Alpha Centauri it wouldn't get there for over 78,000 years. If we want to send humans to Alpha Centauri we're going to have to figure out how to propel a huge spaceship and some very significant percentage of light speed. If we want to get there in any reasonable amount of time (less than 100 years) then we are going to have to develop engines that can propel a spaceship at around 33,500,000mph.

    60,000mph ain't gonna cut it.

    The acceleration aspect is a good one to discuss and is often left out simply for the sake of making things easier to understand using raw numbers that regular folks can multiply and divide by. A ship traveling to Alpha Centauri would likely spend the first part of its journey accelerating to it's speed, then cut the engines and just coast at that speed (no friction in space), then turn around and blast the engines at the halfway point to decelerate until it arrived. Or it would have to spend the entire first half of the journey accelerating and the second half decelerating with no cruise inbetween depending on how fast it could accelerate.

    As far as how much acceleration people can handle. The average person can withstand around 5gs for a short amount of time before passing out. Fighter pilots and astronauts that wear pressure suits can withstand up to around 9gs briefly. So without any sort of dampening technology aboard the spaceship then the acceleration would have to be sustained at around 1g. Any higher sustained g's would screw the crew up. But when talking about the technology required to even build a generation starship I'm pretty sure a whole lot of g dampeners and whatnot would be involved to negate the effects of high g's to keep the crew from feeling it themselves. Some sci fi books discuss this talking about how their big star battle ships have g dampeners that allow the ship to accelerate at like 60gs but the crew only feels 6gs or something.

    Navigating in space isn't something to worry about. Space is extremely empty. Even our Solar System is mostly empty. The Sun holds 99.8% of all the mass in the solar system. Meaning 99.8% of all the "stuff" in the solar system, dust, planets, asteroids, moons, etc, is the Sun. After that is Jupiter which takes up a huge chunk of the other 0.2% The rest of it is basically just empty space. The solar system is so "empty" that NASA doesn't even calculate whether or not it's probes will smack into an asteroid or something when passing through the asteroid belt on their way to the outer planets because the odds of it hitting anything are virtually zero. If you think the Solar System is empty then interstellar space is REALLY empty. We at least have planets and asteroids and stuff in the solar system, there is virtually NOTHING between the stars.

    Basically you could draw a theoretical straight line from Earth to the other side of the whole Milky Way Galaxy with it's billions of stars and planets and comets and whatever else is out there and you wouldn't hit anything. Our pictures of space are always from a perspective that make stuff look really close together. Our solar system models do the same thing. But remember, our closet neighboring star is 25,000,000,000,000 miles away from us. Even things as huge as stars, you'd have to be trying if you wanted to run into one with a spaceship.

    That's why Project Starshot is talking about launching a bunch of tiny stamp sized micro spaceships at Alpha Centauri. They aren't worried about anything in space messing up the trajectory of their little stamp starships, there's almost nothing out there.

    Hope this all helps :wink:
     
  11. tecoyah

    tecoyah Well-Known Member

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    What would be the point of going to a star if we simply built a huge station and moved there instead.
     
  12. OldManOnFire

    OldManOnFire Well-Known Member

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    I know 60K mph is not fast when we're talking astronomical distances but it's the best we can do today...or 38K mph? And even though it's slow it would be pretty neat to have a spaceship with a couple hundred passengers buzzing through our solar system then on to the next solar system...no matter the amount of time. And I would guess that as technology advanced for faster travel it can be retrofitted while in space...depending on the required materials and processes. Even the second launch could bring the new technology to the first spaceship? No matter the speed of the spaceship it's a pipe dream due to the amount of money required.

    Regarding navigating at very high speeds I was thinking more about smaller objects that we don't know exist and cannot preprogram...like asteroids or other space junk.

    And the other unknown is the effects high speed, low gravity, interstellar travel might have on humans and cargo? Maybe living organisms from Earth simply cannot deal with that kind of travel?

    Yes...always enjoy the discussion...
     
  13. OldManOnFire

    OldManOnFire Well-Known Member

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    Curiosity...
     
  14. Nightmare515

    Nightmare515 Ragin' Cajun Staff Member Past Donor

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    Human manifest destiny mainly and the drive for us as a species to go and colonize another world. That drive is innate in human beings. Right now our goals are to get people to Mars and start a colony there. In a few decades or hundred years that Mars colony will continue to grow and eventually likely become it's own self sustaining planet outside of Earth. Then we will want to colonize other places, maybe floating airship cities in the atmosphere of Venus, or colonies on Ganymede, etc. Once we do all of that then we will just want to keep on going, it's how we humans are we are designed that way by nature.

    You are right though and it does actually make sense in the long run to just build a bunch of huge space stations to put people on if we are so keen on getting off of Earth. Especially when as crazy as it might sound it is literally more feasible for human beings to build the actual Death Star than it is to send human beings to another star lol
     
  15. Nightmare515

    Nightmare515 Ragin' Cajun Staff Member Past Donor

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    I agree it would be cool to see humans build a generation ship. I would give anything to be alive at a time when I could at least see the internet pictures of engineers building a huge ship like that up in orbit. I will likely be long dead by the time we humans even begin construction on anything like that but I wish I could at least see them start. It's sadly just not anywhere near feasible right now nor will it be any time soon. For one the costs would be mind blowing, it would take trillions of dollars to build something like that right now. And the biggest problem is that it just wouldn't make any sense whatsoever outside of "it's cool" and nobody is going to fund that. Trying to find investors to help build a spaceship that will get to its destination 50,000 years from now is unlikely...I absolutely love Astronomy and Astrophysics, but even I wouldn't donate even 5 dollars for something like that.

    Whether or not this theoretical spaceship could be retrofitted while in space is debatable for sure but highly doubtful. Most of the theoretical propulsion drives that we have come up with require different sources of fuel for one. So lets say we launch our spaceship with huge ion drives because they are the most fuel efficient. Ion drives are electric propulsion systems that accelerate ridiculously slow but take virtually no fuel to move. We have those now on some space probes. New Dawn uses one. Then lets say our next spaceship is powered by nuclear fusion drives. Those require actual fuel in the form of Helium-3 and Deuterium. Fusion drives are actually being considered for interstellar missions right now because they can provide enough speed to get a probe to Alpha Centauri in about 100 years or so. So they are a plausible candidate for our next spaceship to use.

    So we'd have to first mine enough Helium-3 to use for fuel (I don't feel like doing all the math to determine how much would be needed to accelerate a huge generation ship with X amount of mass). So we'll just say it will require A LOT, because it will. And we have to mine it from the Moon because that's the closet place to us that has the amounts we need to power stuff like this. So we have to mine enough to power our current ship AND enough to give to our old ship as well as drag along the engineering stuff and parts and pieces and engines themselves to transfer to our old ship. We also have to match velocities with our old slower ship in mid flight which will cause us to expend fuel slowing down. Then transfer the stuff, then speed back up again which requires more fuel. Way too much and virtually impossible to do.

    In regards to navigation, still your concerns are unnecessary. There isn't even that much "small stuff" in space in regards to the amount of "space" there is in space. Even the most dense part of our Solar System is virtually empty. New Horizons (the probe that went to Pluto) is currently on its way out into the Keiper Belt which is the "most dense" part of our Solar System with the most stuff floating around out there. New Horizons doesn't have a projected path that NASA preprogrammed so that it doesn't hit something out there and they are worried about it, but actually the opposite. New Horizons is stuck on a pretty much straight line because it doesn't have the fuel to move very much. So once it got past Pluto there was a rush for NASA to find something in it's path that it WOULD get close enough to for it to actually study. And luckily the were able to find a couple things that it will fly "close" enough by to study them. And by "close" we're talking several thousand miles.

    Like I said you have to really "try" to run into something in space. NASA wasn't panicking because New Horizons might hit something in our densest part of the Solar System because it can't move out of the way, they were worried that it wouldn't even get close enough to anything in our densest part of the Solar System for them to look at because it can't move :wink:

    It wouldn't be the low gravity that screws up the crew on long missions but rather cabin fever and psychological effects of being on a spaceship with only a few hundred other people until you die. A ship expected to travel that far wouldn't be like what you see in the ISS with Astronauts floating around in low gravity. It would likely by a cylindrical ship that simulated 1g by spinning on it's axis with floors on the walls and ceiling and things like that like that colony ship at the end of the movie Interstellar if you've seen that movie.
     
  16. tecoyah

    tecoyah Well-Known Member

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    Agreed....but there is no reason we could not simply move the station as easily as a ship.
     
  17. tecoyah

    tecoyah Well-Known Member

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    So...we move the station. In space the shape and size do not effect mobility.
     
  18. OldManOnFire

    OldManOnFire Well-Known Member

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    Because of the required costs and yet unproven drive technology it's obvious it will be many decades before this can possibly happen. And I would donate my latte money for such a venture because unless we discover some new physics some type of multi-generational spaceship will be the natural progression for Earthlings to leave this rock and venture out. First this will be to explore our closest neighbors but once we start thinking about exploring the outer half of our solar system we might as well be prepared, like Voyager 1&2, to keep on trucking to the next solar system. Prior to this we will put some more humans on the Moon, maybe a small colony on the Moon, then get a couple of humans to Mars, maybe a small colony, but then what do we do without the capability to have multi-generational space travel? We can hope that within the next 100 years we can develop better/faster drive technologies that can greatly reduce interstellar travel time...but even with much higher speeds it will still be a one-way ticket on a multi-generational cruise.

    I can imagine that retrofitting an orbiting spaceship with new drive technology will be a logistical nightmare...a huge challenge. But maybe we get lucky? Maybe a new ship replaces an old ship? Maybe when a ship is considered spent is where we build another colony? We're talking about 100's of years of time for such a venture so I'm thinking there will be lots of possibilities we don't know about today.

    Again, I understand the logistics, but it's unlikely we will ever have all the answers by launch day. So we go with what we got and venture out.

    We also don't know all of whats 'out there'? Do we 'panic' more knowing we have human passengers aboard? Does it make a difference if we have 2 passengers versus 200? IMO we're not going to reach these types of speeds anyway so a moot point.

    I'm thinking humans will be challenged by all sorts of issues; variable gravity, confinement, time, personalities, light, boredom, fear, unknown physiological issues, a lack of good looking women, etc...
     
  19. OldManOnFire

    OldManOnFire Well-Known Member

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    Call it whatever you wish but it must be multi-generational sustainable and like Nightmare says it will take a very long time so from this time perspective it almost seems a stupid thing to attempt...but I continue to prefer that we keep our space exploration idea moving forward and IMO a large spaceship will be the answer...
     
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  20. Nightmare515

    Nightmare515 Ragin' Cajun Staff Member Past Donor

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    We actually have a better understanding of whats out there than you may believe. We understand how solar systems form and we understand that most of the "stuff" in a galaxy is revolving around stars unless you are in a nebula or something. Even within a solar system we see how far away stuff is from each other. Space is enormous and the stuff in space is tiny compared to the amount of space itself. Granted there is some stuff out there that is floating around between the stars but I mean you would have to be ridiculously lucky (unlucky) to hit anything. It would basically be like to kids with BB guns on opposite sides of Yankee Stadium trying to shoot their guns and make their BB's collide in mid air. It's virtually impossible to do that there's simply way too much volume in a stadium in regards to those 2 tiny BB's.

    There is some stuff out there that we cannot see in visible light such as a super cool Brown Dwarf that only emits IR radiation so it's invisible to the naked eye. But even in regards to something as huge as that, you have a better chance of hitting the jackpot lottery 5x in a row than accidentally running into one of those on your way to your destination star.

    Sci-Fi and pop culture have put a false image into peoples heads about how space actually is. We see moves like Star Wars where the heros are ducking and dodging their way through asteroid belts and things like that when in reality I could drop you in the middle of the densest part of the asteroid belt and you would look like you were in the middle of deep space because you wouldn't see any asteroids. Well you might see a couple out in the distance as tiny specs if you looked close enough or had a telescope with you and knew where to look.

    When I say "nothing" I don't technically mean "nothing" I mean nothing relatively big. There is a lot of space dust and micrometeorites out there that our probes DO have to contend with. Because of this probes are shielded with what's referred to as Whipple Shielding which is basically body armor for the probe. A generation ship would certainly have to contend with that and would certainly have to have some type of armor to protect it.

    Once we start talking about speeds in the fractions of light speed then those tiny particles start to become more troublesome and a ship would need some sort of shielding to protect it. At those speeds I do believe dust particles basically ionize and become some sort of plasma or something I think. Not too sure I haven't researched that subject in awhile.

    So yes there is "stuff" in space just not a lot of big stuff like large asteroids or planets or anything.
     
    Last edited: Nov 14, 2017

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