4 ms·

I think the Fermi Paradox is more easily explained by three things. 1. It is possible that self-aware life with the ability to manipulate the environment is ra

I think the Fermi Paradox is more easily explained by three things. 1. It is possible that self-aware life with the ability to manipulate the environment is rare. Most people assume that self-aware life will build cities, but crows, cetaceans, octopuses, and elephants don’t do so despite having quite a bit of smarts. They lack hands. 2. It is possible that the speed of light is a very real boundary and that cannot be broken limiting the ability of life to spread itself within a life time. As anything that persists spends energy to do so, it may be that living things won’t willingly take the chance for themselves and posterity of living on a ship for many generations. 3. Nuclear war. Most intelligent life is predatory. If you want to manipulate your environment, you also have to focus. Most animals with eyes on the front of their heads that can focus well, are also predators. That predatory instinct creates violence, and that leads to war in pack-oriented social predators. With enough advancement, nuclear weaponry and war may be the rule not the exception.

admax88qqq 4y ago
> living on a ship for many generations. Thanks to time dilation, with 1g of acceleration you can go anywhere in the galaxy and back in 40 years.
- elkos 4y ago
  provided faster than light travel is possible right? Cause the galaxy is pretty big isn't it?
  - 4gotunameagain 4y ago
    I think he means that your local time passed will be 40 years, while much longer for the rest of non accelerating people. And of course I have no idea if the maths check out :)
    - qayxc 4y ago
      > And of course I have no idea if the maths check out :) The galaxy is about 90,000 ly across so a time dilation of about 0.004 is required to get to the 40 yr figure. Doing the Lorentz transformation results in a required speed of 299,790 km/s or 99.999% the speed of light. Needless to say that this is indeed practically unachievable by any macroscopic space craft. Even if you were able to accelerate a ship to such speed, said ship wouldn't survive the journey as radiation from the blue-shifted light of stars in front of it as well as interstellar particles would destroy any known material.
- credit_guy 4y ago
  Here's one little trick to quickly estimate the fuel you need to get to 99.9% of the speed of light. You take the rocket equation and replace the velocity with the "rapidity", which is the inverse hyperbolic tangent of the velocity expressed as a percentage of the speed of light. That sounds like a mouthful, but you can actually estimate this in your head. The inverse hyperbolic tangent is 1/2 log((1+x)/(1-x)). If you plug in 0.999, you get 1/2 log( 1.999/0.001), which is indistinguishable from 1/2 log(2000). If you ever did rough estimates with logarithms, you know that you only need to remember 2 logarithms, log(2) and log(10). They are 0.7 and 2.3, so log(2000) is roughly 0.7 + 6.9 = 7.6, and half of that is 3.8. You now apply the classical (non-relativistic) rocket equation as if the final velocity is 3.8 times the speed of light (which is 300000 km/s). That's about 1 million kilometers per second. If you use the best chemical propellants, you can reach an exhaust velocity of about 5 km/s, so the ratio is about 200000. You take exponential of that, and that's how much fuel you need for each unit of cargo you want to ship. You need to use some multiple precision library, because with normal (double) precision floating point numbers, you will get an overflow if you try to do exp(200000). But let's say you want to use the VASIMIR engine, that reaches (theoretical) exhaust velocities of 100 km/s. Then your ratio will only be 10000. Exp(10000) is still out of reach of normal numerical libraries. The even more theoretical fragment fission rocket engine reaches exhaust velocities of 10000 km/s. Now we get Exp(100) which is about 3 followed by 43 zeros. If you want to accelerate a space capsule weighing one ton to 99.9% the speed of light, you need that many tons of fuel (assuming a 100% efficient fragment fission rocket). That's a bit unfortunate, because it exceeds by a few orders of magnitude the mass of all the stars and planets in the galaxy.
hotpotamus 4y ago
I wonder why they'd leave their home systems? There's no reason to suspect there's anything out there that they can't make close to home - presumably it's all just mass and energy (which are on some level the same thing anyway). Depending on the type of star they live around (seems like a fair assumption they need a star for energy), it'll run down quickly or slowly, but so will every other energy source in the universe. That is to say that I think the answer to the Fermi Paradox is simple, everyday Nihilism.
LorenPechtel 4y ago
#2 assumes we won't develop life extension to the point that they aren't generation starships. I find this an unlikely assumption.
- AstralStorm 4y ago
  Even if we do, there's no reason to think they would reach us. Shooting a bullet at random possibly habitable world is likely, at Earth or even Sol in particular, no. Barring some sort of teleportation technology or whatever FTL is, the amount of energy required to travel there in reasonable time is huge.

admax88qqq 4y ago

> living on a ship for many generations. Thanks to time dilation, with 1g of acceleration you can go anywhere in the galaxy and back in 40 years.

elkos 4y ago
provided faster than light travel is possible right? Cause the galaxy is pretty big isn't it?
- 4gotunameagain 4y ago
  I think he means that your local time passed will be 40 years, while much longer for the rest of non accelerating people. And of course I have no idea if the maths check out :)
  - qayxc 4y ago
    > And of course I have no idea if the maths check out :) The galaxy is about 90,000 ly across so a time dilation of about 0.004 is required to get to the 40 yr figure. Doing the Lorentz transformation results in a required speed of 299,790 km/s or 99.999% the speed of light. Needless to say that this is indeed practically unachievable by any macroscopic space craft. Even if you were able to accelerate a ship to such speed, said ship wouldn't survive the journey as radiation from the blue-shifted light of stars in front of it as well as interstellar particles would destroy any known material.
credit_guy 4y ago
Here's one little trick to quickly estimate the fuel you need to get to 99.9% of the speed of light. You take the rocket equation and replace the velocity with the "rapidity", which is the inverse hyperbolic tangent of the velocity expressed as a percentage of the speed of light. That sounds like a mouthful, but you can actually estimate this in your head. The inverse hyperbolic tangent is 1/2 log((1+x)/(1-x)). If you plug in 0.999, you get 1/2 log( 1.999/0.001), which is indistinguishable from 1/2 log(2000). If you ever did rough estimates with logarithms, you know that you only need to remember 2 logarithms, log(2) and log(10). They are 0.7 and 2.3, so log(2000) is roughly 0.7 + 6.9 = 7.6, and half of that is 3.8. You now apply the classical (non-relativistic) rocket equation as if the final velocity is 3.8 times the speed of light (which is 300000 km/s). That's about 1 million kilometers per second. If you use the best chemical propellants, you can reach an exhaust velocity of about 5 km/s, so the ratio is about 200000. You take exponential of that, and that's how much fuel you need for each unit of cargo you want to ship. You need to use some multiple precision library, because with normal (double) precision floating point numbers, you will get an overflow if you try to do exp(200000). But let's say you want to use the VASIMIR engine, that reaches (theoretical) exhaust velocities of 100 km/s. Then your ratio will only be 10000. Exp(10000) is still out of reach of normal numerical libraries. The even more theoretical fragment fission rocket engine reaches exhaust velocities of 10000 km/s. Now we get Exp(100) which is about 3 followed by 43 zeros. If you want to accelerate a space capsule weighing one ton to 99.9% the speed of light, you need that many tons of fuel (assuming a 100% efficient fragment fission rocket). That's a bit unfortunate, because it exceeds by a few orders of magnitude the mass of all the stars and planets in the galaxy.

hotpotamus 4y ago

I wonder why they'd leave their home systems? There's no reason to suspect there's anything out there that they can't make close to home - presumably it's all just mass and energy (which are on some level the same thing anyway). Depending on the type of star they live around (seems like a fair assumption they need a star for energy), it'll run down quickly or slowly, but so will every other energy source in the universe. That is to say that I think the answer to the Fermi Paradox is simple, everyday Nihilism.

LorenPechtel 4y ago

#2 assumes we won't develop life extension to the point that they aren't generation starships. I find this an unlikely assumption.

AstralStorm 4y ago
Even if we do, there's no reason to think they would reach us. Shooting a bullet at random possibly habitable world is likely, at Earth or even Sol in particular, no. Barring some sort of teleportation technology or whatever FTL is, the amount of energy required to travel there in reasonable time is huge.