Aliens, hell yes, hell no, get outta here.

Does extra terrestrial life exist? Undoubtedly. The statistics alone should be enough to answer more than confidently in the positive.

does intelligent life exist off this planet? Far less likely, yet... the statistics should also be overwhelmingly in favor of that to be true.

consider:
https://bigthink.com/starts-with-a-bang/where-big-bang/#:~:text=The answer?,million light-years for simplicity.
"The theoretical center of the Big Bang is about 17 million light-years away from where we are today. (Estimated to be between 14 to 20 million light years away)

"That’s remarkably close by! After all, we can see for some ~46.1 billion light-years in all directions, and 17 million light years is only 0.037% of the radius-of-the-Universe away from us." (Note: to be able to see ~46.1 billion light-years, there has to be something to see. Supposedly, those things that we see all came from the point of origin of the Big Bang).

If we take into account that the objects we can see at the outer reaches of the far far far edges of the observable universe all passed through a radius from the Big Bang equal to our own distance from the Big Bang, then we have to recognize a vast plenitude of galaxy- like formations have been in existence far longer than our own galaxy.

The time frame and conditions for examples of evolutionary life to grow to high levels of intelligence have been more than enough to produce billions of starter species. Many wouldn't make it, but once a certain level of intelligenc, coupled with technology, had been reached, survival into the hundreds of thousands, even millions of years becomes more and more likely. An analogy would be the average age of the human species over time. In pre- and early civilizations, individuals were almost as likely to die in their first ten years as to reach adulthood. However, having been able to reach full maturity, they were more likely to reach old age then to die in their middle adult years. While the average age of early civilized humans may have been somewhere in the thirties, most adult actually survived into their sixties and seventies, with many of them into their nineties.

Think of intelligent alien civilizations in the same way. Once they had reached some form of maturity, a civilization may be able to continue beyond the types of disastrous conditions that would wipe out younger civilizations. Running out of natural resources would hurt, but more likely, that would simply force an intelligent and advanced species to learn to create resources. Force them to expand across their solar system to give them even more options for survival. At some point, their technology might allow them to build something like a planet that can move between stars when their old star begins to fade. If they could develop the technology to keep a planet alive without a sun, they would not have to worry about the speed or time it takes to slingshot their planet out of orbit and into the orbit of another star 50 or more light years away. So what if it takes a thousand years to actually get to the new star.

Consider that the galaxies that have already passed through our current location have already had a similar amount of time as our own, to cool and form and take on the conditions that allowed life to form here, plus they have had millions more years on their way to where they are now.

What we see, when we look out at these other galaxies are the weak remains of their strongest energies from thousands, hundreds of thousands, million and billions of years ago. We are not going to ever know what energy signals they are currently putting out. It is highly likely that we are not the first and are very close to the bottom 0.037% of what is out there.

-Will

 

Shadows. They just need the right kind of light to cast them.
https://www.amazon.com/Flatland-Rom...ocphy=9002459&hvtargid=pla-487669270727&psc=1


-Will

 

That's wrong, so the rest of the post doesn't really follow.

 

I linked my source. Is the number wrong or is the proportion wrong? Are we out on the outer rim of the Universe? Are there not far older galaxies than ours? How does this information nullify the rest of my reasoning?

-Will

 

Okay, I'm wrong.
Here is a more authoritative source.
https://spaceplace.nasa.gov/galaxies-age/en/#:~:text=Astronomers believe that our own,about 500 million years ago.
It says most galaxies formed, like our own, within a few million years of the Big Bang. So, my premise is fundamentally flawed.

Now, take my logic and apply it to our solar system and compare it to other solar systems.

-Will

 

A summary of current understanding:
The Big Bang had no centre. The Universe has no centre. Every observer sees themself at the centre of the expansion. The width of the visible Universe is about 92 billion light years, not 27.5 billion light years, due to the expansion of space-time. The Universe is understood to be many time bigger than this, but how many times bigger is unknown. Due to expansion, many galaxies will eventually pass beyond the horizon. Intuition and natural language is not a good substitute for mathematics when discussing physics and especially cosmology. One tends to end looking as foolish as Scott Adams.

 

https://spaceplace.nasa.gov/galaxies-age/en/#:~:text=Astronomers believe that our own,about 500 million years ago.

So it would be impossible for 46 (92/2) billion light years to be traversed in the time the universe has been around.

A point then: our galaxy is nearly as old as the Universe and is typical for that. There may be a few hundred million years difference between the oldest galaxies and our own. Not a large amount of time on a cosmic scale.

Life, in our case, first developed at almost the moment conditions allowed. If that is typical, and from a cosmic time scale, that's still a lot of time. Life seems inevitable where conditions support it.

From a NASA web site:
"For the first billion years of Earth’s existence, the formation of life was prevented by a fusillade of comet and asteroid impacts that rendered the Earth’s surface too hot to allow the existence of sufficient quantities of water and carbon-based molecules. Life on Earth began at the end of this period called the late heavy bombardment, some 3.8 billion years ago. The earliest known fossils on Earth date from 3.5 billion years ago and there is evidence that biological activity took place even earlier - just at the end of the period of late heavy bombardment. So the window when life began was very short. As soon as life could have formed on our planet, it did." -https://cneos.jpl.nasa.gov/about/life_on_earth.html

If we can consider ourselves as a model of typical evolution, then any conditions that allow for our form of life that has lasted for about 4 billion years, should potentially evolve life to our level. Civilization and technology would follow a similar path.

It seems highly likely that conditions conducive to life and evolution across the universe could exist in uncountable locations and many of those locations have existed for much longer then or own.

Perhapse we are not at the bottom off the evolutionary time scale, but there should by billions of planets in the universe where the conditions and time has been even more favorable. It is far more likely, if life can evolve to travel the distance needed to bring them from there to here, others will achieve that ability before we do. However, there is even more likelihood that they will be so busy in the many other places to explore, that we may never see them until we get off our planet and get out there with them.

The Earth is about 1/3 the age of the Universe. There may be places where life could exist that are a old as 1/2 the age of the Universe. That's plenty of time to grow highly advanced technologically.

-Will

 

You are incorrect.

How can it be understood that the universe is 93 billion light years across and yet only 13.8 billion years old? - Quora

 

Can you be more specific? I thought my last post's observations were using the same numbers your link gave.

"We only know what we can see, and what we can see is 14 billion years old. So the observable universe is that old, and with the speed of light and the accelerating expansion of the universe, it's at least 93 billion light years across."

To be clear, I'm not arguing against these numbers. I have no problem with them at all. I was only noting that I was wrong in describing a center origin to the Big Bang. I stand corrected on that.

If I am incorrect in other statements, please let me know which ones. Thanks.

-Will

 

My interpretation was that you meant it's impossible for the observable Universe to be larger than its age implies. Your sentence is incorrect because the cosmic microwave background radiation (CMBR) has traversed 46 billion light years in 13.8 billion years - having set out about 370,000 years after the Big Bang. Space-time has been stretched - this is why the CMBR and other light from distant epochs is redshifted. The estimated redshift for the CMB is 1,090 - that is, the wavelength of the original radiation has been stretched by a factor of 1,091. Its black-body spectrum currently peaks at a wavelength of 0.187 cm, so the original peak would have been at 1.72 μm - in the near infrared.

There are some that disagree with the current interpretation, but theirs is not the mainstream consensus. It's not a debate I'm interested in entering as I have neither the time nor the inclination to invest. Back in the 1960s, I was more sympathetic to Fred Hoyle's Steady State theory, but the observational evidence demolished it despite Hoyle's efforts to shore it up. Some other theory might yet supplant the current understanding, but it will need to explain the observational data. Ideally, it will also need to be falsifiable - that is, make testable predictions that the current models either do not or that differ in what they predict.

With respect, sometimes I find it requires quite some effort to untangle the essence of what you are trying to communicate. That might well be a failure on my part, not yours. Language can trip us up - especially, when discussing complex subjects such as this.

 

Yeah, no. I want trying to say that. I agree that if we can detect objects out that far, there can be no central location for a Singularity. That all is new information to me. The background radiation wouldn't need to travel anywhere if everywhere started all at once, even if it is expanding.

-Will

 

There is no central location for a singularity because neither universal coordinates nor reference points exist to locate it. The Universe looks pretty much the same in its expansion wherever one is situated within it. One view is that the Big Bang created space-time, within which we find ourselves. Other views such as conformal cyclic cosmology (CCC) offer somewhat different propositions. CCC claims to find evidence in the CMBR that at least one other Universe preceded the Big Bang.

Inflation theory is seen as problematic because there is no known mechanism for it to stop. One theoretical view is that inflation is eternal and still going on in parts of the Universe beyond the observable horizon. This sounds superficially similar to Hoyle's later Quasi-Steady State theory - although that theory did not depend on inflation to remove the evidence from view, and it was inconsistent with observations. Any theory that invokes events that we can never observe nor measure is not physics, but metaphysics.

 

What might an advanced technology that can travel faster than light, look like from here? Looking out at the nearest groups of stars that have planets that could support Earth-type life, what might we expect to see?

If, like the Romulans, their ships were powered by tiny black holes, their gravity signatures might be identifiable. First, however, we would need to consider how long these advanced civilizations might have been at the point where such technology was being used. If they are only a hundred or two hundred years ahead of us, their radiant signatures likely would not have had a chance to reach us. But, if they were several thousand years ahead of us, we may be able to detect signs of their activity from a few hundred light years away.

If we were two hundred years away from faster than light travel, if such a thing was possible, we would only expect to detect signs of such technology if those other beings were more than two hundred years ahead of us. Three, four or more centuries ahead is most likely.

What if a star was observed to dim regularly by a crossing planetary silhouette? We record its orbital cycle and the amount of change in the stars illumination, but over a hundred years, that dimming effect grows slowly less and less. It could be that the orbital plane of the planet(s) have shifted. That is likely to happen on occasion, but could it also be attributed to the growth of an industrial technology that generates artificial light to illuminated their night sky?

If that planet was three hundred light years away, we could buy watching the maturation of their equivalent industrial age while they were, in fact, two hundred years or more past it.

-Will

 

On the other hand why would aliens that advanced even bother coming in person when a probe can do all the work for them?

 

Good point. Perhaps such probes would take the form of native animal life, say something like a sweat bee that can fly, maneuver, pass easily into restricted areas. I have noticed that some flying insects seem more intent on hovering around our faces and taking skin samples, then in foraging for food or defending against predators. They act like tiny robotic probes .

Who knows what they are up to when we aren't there to see them.

-Will

 

Now at some point, space out-ran the matter, so there may have been a discrete shape before the monoblock shredded out into ribbons?

I wonder if the universe was ever at one atmospheric pressure or room temperature at the same time?

 

The universe was at room temperature, 293K, 15 million years after the Big Bang. At that time, the scale factor would be about 100, so the number density (mostly hydrogen molecules and helium atoms) was about one million times the current number density of 0.25 particles per cubic metre, that is, 250,000 m^-3. The number density of air molecules at room temperature and pressure is about 2.6 x 10^25 m^-3, so over one hundred million trillion times denser. Even if the density were the same, you wouldn't be able to breathe as there would be no oxygen*. The actual average number density would be lower than that of a good laboratory vacuum.

*If there was oxygen around, there would be something very wrong with current cosmological models. The abundance of elements heavier than lithium in observations of the early universe is an important test of the validity of those models.

WMAP Big Bang Elements Test (nasa.gov) - Note that this page is not wholly accurate with regard to how atoms of some elements are now thought to have been formed.
The origin of the elements: a century of progress | Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences (royalsocietypublishing.org)

 

A suitably advanced alien culture would not need to send out probes. Advances in multidimensional computer modelling would allow enough scenarios of local galactic civilization growth to provide accurate forecasts and understanding to comprehend any applicable world's development within a few degrees of accuracy. Would it be worth the trouble to just go and visit? it's hard to understand the motivations of an alien intelligence, let alone one highly evolved, possibly hybrid-artificial and almost certainly vastly more intelligent.

But I don't think there would be much point in reaching out, beyond basic threat elimination if such a threat were assessed. The fact we're typing back and forth as our species has already achieved spaceflight indicates to me that such potential modellers do not exist or we were judged mostly harmless. Douglas Adams was right again.

 

The assumption that advanced alien civilisations create megastructures might well be incorrect. As Richard Feynman put it "there's plenty of room at the bottom". Miniaturisation would seem to present a much lower hurdle to cross. As soon as any possible virtual world can be simulated in whatever level of detail is desired, why go to the bother of crossing vast and unfriendly interstellar distances? Such civilisations might indulge in stellar uplifting to extend the lifespan of their home stars but creating huge solid structures that encompass stars is likely to be unnecessary.

 

And if an alien culture has "dark forest" scenario worries, megastructures like a Dyson sphere is one of the best ways to advertise that your culture has reached a pretty big technological threshold and could be a threat. Conversely it could also be a projection against such threats by showing off technical prowess. "We built this. We're not bothering you. Stay away."

But if populations decline naturally after a post-industrial change (maybe not, we hardly even no for sure about humans), it doesn't seem like they'd need the space, anyway.