[MrWonderful]

You have not the slightest clue of the costs of:
1. Sending equipment to MINE those "resources" you think are out there for our taking,
2. The cost of enclosing those "resources" and bringing them back to earth,
3. How many hundreds of millions or billions of dollars have been spent searching for life you keep crossing your fingers hoping to find,
4. "Dude" is such childish jargon. Are you a teenager?
5. Understanding millions of topics is costing taxpayers trillions of dollars and the researchers don't give a damn about cost/benefit analysis. So we learn more about black holes. You cannot begin to answer how that benefits anyone on earth besides the researcher who collects from government coffers.

[quetzalcoatl]

...the expansion and contraction of space.

I'm picturing a cylindrical geometry that expands and contracts in waves to propel objects moving through it. An interstellar colon, as it were. I call it space peristalsis.

[XogGyux]

I'm picturing a cylindrical geometry that expands and contracts in waves to propel objects moving through it. An interstellar colon, as it were. I call it space peristalsis.

Explains Uranus?

[quetzalcoatl]

Explains Uranus?

Some people are saying Uranus has rings around it. Cannot personally confirm this.

[Negotiator]

We know we can colonize the Milky Way, even with current technology. It will take many millions if not billions of years, and communication between star systems would be extremely hard to do. Still, it would be possible.

So, assuming there was another sentient species out there, why wouldnt it be possible they spawned millions if not billion years earlier than us and thus would have already arrived here ? Are we simply the first ones ?



The astrophysicist and YouTuber Dr. Becky recently estimated that there are a 10,000 planets with sentient life in the visible universe. I havent read her book about it, but here is what I heard (from her and other sources).



For example in order to have a lot of elements heavier than iron, our solar system was close to a kilonova when it formed. A kilonova is an event of a neutron star colliding with a compareable object - either another neutron star, a white dwarf, or a stellar black hole. A kilonova creates a lot of heavy elements, some of which are required for life to exist. Kilonovas are rare and most star systems arent exposed to one during creation, which means the heavy elements are a lot more rare in most star systems compared to our own (we can find the ones that are the same as ours easily by evaluating the spectrum of the star. So far we only have found one other star thats like our own and was also exposed to a kilonova during creation).

Another example how unique our star system is is how amazingly silent our Sun is compared to all other stars we've observed nearby. This is probably because our star rotates very slowly. While red dwarf stars specifically are known to have outbursts that increase the energy output by a factor of a 100 for short amounts of time. Which creates extremely harsh conditions for life and probably makes complex life impossible.

Another example is how the amount of nuclear elements in the core of our Earth is just right so we can have a constant magnetosphere, with only a 15 mio year gap 550 mio years ago that we recently found that put our atmosphere and later oceans in great danger of getting stripped away by the sun, but fortunately magnetism restarted.

Yet the amount of radioactive elements in the core wasnt so high to give us high vulcanism and an excessively dense atmosphere, like Venus has. If Venus had the orbit of Earth, its surface temperature would be 400 degree celsius - manageable for some exotic life forms on earth, but far too high for complex life.

So the amount of radioactive elements in our Earths core was really like, fine tuned.

Another example is how our moon was probably extremely important in various stages of the Earths development, for example right when it formed it was so hot that it added additional heat to the heat of the young and relatively weak sun, allowing Earth to end one of its two ice ages, and how it stabilizes the Earth just right, making sure it never rotates on the poles (which would be very detrimental to life).

The status of an ice Earth is by the way stable. Should the Earth be fully covered in ice again, its albedo would be so high it wouldnt change in hundreds of millions of years. Until the Sun gets so hot that it will not only melt the ice, but also thanks to the now much lower albedo heat the Earth up quickly to temperatures incompatible with complex life.

So many things had to go right for our Earth for complex life to prevail here.

And the next step after complex life is of course - sentient life. Our planet held complex life for many hundreds of millions of years before it finally developed one sentient species.

Thats why, despite there being hundreds of billions of stars in the Milky Way alone and hundreds of billions of galaxies in the visible universe, there might only be as few as 10,000 planets which actually developed sentient life.



Thus, based on our current knowledge, complex life seems to be very unlikely. And with only 10,000 such planets with sentient life, but about 2 trillion galaxies in the visible universe, this means we are probably alone not just in the Milky Way, but also alone in our Virgo supercluster (the largest structure bound by gravity).

Therefore, extra-terrestials will arrive exactly - probably never.

And it makes sense. Assuming there is no FTL, why would an extra-terrestial arrive at exactly one point in time ? They would appear at a random point in time. The time of the dinosaurs is just as likely as one billion years in the future, when earth will lose its magnetosphere a second and last time (because radioactivity will be so low at that point that the whole core turns solid), the atmosphere will be blown away and the oceans will be stripped as well and we humans, assuming we still exist, have traveled to other star systems for sure, out of sheer necessity.