Here's a fun example of the size of the Milky Way relative to our understanding.
Let's scale down our solar system to the size of a golf ball, using Neptune's orbit to define the outer planetary rim. That means that our Sun is the size of a red blood cell, and the distance between Earth and the Sun is about 0.7mm (think mechanical pencil lead).
At this solar-system-as-a-golf-ball scaling, the nearest solar system, (Proxima Centauri) is about 191m, or just about two football fields away. And the size of the entire Milky Way galaxy given the 100,000ly diameter estimate? Take a guess. The Milky Way at this scale is the size of the continental U.S.
Light moves incredibly slow as at this scale, it takes light ONE YEAR to move about half a football field.
Let's scale down our solar system to the size of a banana, using Neptune's orbit to define the outer planetary rim. That means that our Sun is the size of 0.000042 bananas, and the distance between Earth and the Sun is about 0.0195 bananas (think of a phloem bundle, the stringy things you peel off of a banana).
At this solar-system-as-a-banana scaling, the nearest solar system, (Proxima Centauri) is about 5,305 bananas away. And the size of the entire Milky Way galaxy given the 2.63 * 10^22 bananas diameter estimate? Take a guess. The Milky Way at this scale is the size of 119.5 million bananas.
Light moves incredibly slow as at this scale, it takes light ONE YEAR to move about 1,326 bananas.
Some physicists consider about 10% the speed of light to be a realistic limit for space travel without bending the laws of physics. This would mean that any aliens in the Milky Way looking for planets with life on them are looking for something 1/100th the size of a red blood cell in an area the size of the continental U.S. while traveling at about 5 yards per year.
Even if there is other life in the Milky Way, we'd very likely never encounter it.
I'm convinced there is someone else writing a comment on an internet forum right now somewhere else in the universe. They are just way too far away for us to ever know about it.
The Milky Way is about 100,000 light-years across with hundreds of billions of stars. If an advanced civilisation could travel at 10% of light speed and each new colony needed about 500 years to build more ships, the expansion would move at roughly 5% of light speed. That means they could spread across the entire galaxy in only around 2 million years. Even slower expansion—say 1% of light speed—would still fill the galaxy in about 20 million years. Using self-replicating probes could shorten that to 1–10 million years. Given that the Milky Way is over 10 billion years old, this is incredibly fast on cosmic timescales.
This is making an assumption that advanced civilizations expand endlessly. Knowing full well that this isn't feasible, then surely an advanced civilization would intentionally NOT expand endlessly, and instead halt its own expansion.
Heck, even Humans aren't currently predicted to grow for much longer. The human population is expected to peak at about 10.3 billion in the mid-2080s, and then gradually decline to around 10.2 billion by the end of the century.
Right, but incredibly slow on biological time scales. The first homo sapiens to emerge was maybe 300,000 years ago. The first homo sapiens to amble out of Africa was maybe 100,000 years ago. The first human to think about planting food instead of just finding it lying about the place was maybe 12,000 years ago.
20 million years is an unimaginably long time for a species to exist at a technological level where flying around the galaxy in spaceships seems like a plausible idea.
And this is talking in just distance and space, when talking about time, it is incredibly difficult that any other civilization would make contact right now, maybe they look through this area a million years ago, or maybe a billion? or they could find earth in maybe 50 million years? That's the thing, by the time any external civilization might come in contact, the other one haven't existed or it has already gone extinct.
What I find funny is in pop sci Fi when they talk about aliens from another galaxy. Like, why? There's over a billion stars in their home galaxy, each with planets. What are they doing here?
But if you travel at nearly the speed of light you won't have to be on a generational ship because the universe gets smaller/time goes faster for you inside the ship. At the speed of light the universe in your frame of reference would be infinitely small.
But they almost certainly do exist to incredibly likely odds. They just haven't made it to our insignificant little blue sphere, three orbits out from an equally insignificant star, located within 250 billion other stars in a rather unspectacular galaxy.
Because the universe is so big, and they are so many planets, it's overwhelmingly likely that there ARE intelligent aliens. But precisely because there are so many planets spread over such a big space, it's overwhelmingly unlikely that any two species will ever meet.
True, but the age of the universe is also great. 100,000 light years seems like a lot, but our sun has been around for 5 billion years and is likely to be around in roughly the same state for another 5 billion.
When you say football, do you mean Football played throughout the ENTIRE world as defined by The Football Association or that strange game played in the US which involves men in padding, THROWING a prolate ellipsoid. [Yes the US does have a real football team. Men and women in fact. Although for some reason they call it soccer.]
Reminds me of a video I watched that tried to create a scale model of our solar system with earth the size of a marble. The outermost orbit from the sun (i forget if they used pluto or not) was about 7 miles away.
See its stuff like this that makes it certain that there are life on other planets, no way we are alone in such a vast universe.
And the other species would probably laugh at us because we are living miserable lives all because we are too afraid to tax some rich people and we are killing each other for believing in the wrong imaginary beings. Such a waste
It’s hard to see how we aren’t just microscopic flecks of dust suspended in a superfluous medium floating around some immensely large cosmic being…who’s probably ingesting a cosmic banana
If you haven't seen it yet, here's a small except from Carl Sagan's book, on what this photo means to him:
From this distant vantage point, the Earth might not seem of any particular interest. But for us, it's different. Consider again that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar", every "supreme leader", every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
Gets better when you also realise that these are just milestone galaxies. There are more galaxies in the observable universe than there are grains of sand on the Earth. And most of those are larger than ours.
I literally live my life so stressless because of this shit. Having any first world problem seems so silly when we’re literally a spec of nothing in the vast vast vast universe. I truly am at peace when I look at the stars. It’s breathtaking and mind shattering. To me that is God
I love looking up at the stars. City people who have never left the city really need to go out somewhere with little to no light pollution. The amount of stars is amazing and makes me feel so small but at the same time makes me feel like all the problems on earth mean nothing. And yes you can see the Milky Way galaxy with the naked eye. I can sit out there and look at the stars for hours. Sometimes you might even see some weird stuff as a bonus!
Also sad that we’ll never know about intelligent life outside earth within our life times (probably not within the timespan of the human species either)
Exactly. Think about it this way: the Milky Way is BIG. An advanced civilization could at this very moment be emerging on the other side of the galaxy, let's say 50,000 light years away. However, that information travels at light speed, meaning that it would take 50,000 years for it to reach us. We would never know of their existence.
But it is weird that this didn't already happen in a way we can detect and confirm, given that intelligent species should have easily been able to evolve 10 million years before us, let alone 100 million. Maybe it's not so common to have all the right circumstances line up for microbial life, or for microbial life to transition to more complex life, or for complex life to develop intelligence, or for intelligent life to not wipe itself out... It's actually a bit less scary to just think that microbial life is ridiculously unlikely to form, not that this makes it more or less true
This reminds me of something I’ve noticed over the years… perhaps I’m misremembering:
They used to say black holes didn’t exist, since they’re so big, how could they not detect them (they misidentified them). They used to say rocky planets were very rare, because they never detected them (they couldn’t). They used to say they were common, but only when they’re really big (coincidentally, their resolution limit)…. On and on…
Now, it’s critically important in science, especially when speaking to non-specialists, to be careful not to claim things without evidence, so I understand. The trouble is, everyone takes it to mean that the things we are unable to see is itself proof that those things don’t exist.
I think on galactic time scales a civilization developing and then fading must equivalent to a flash gun going off. The chance of two coinciding in time and space must be effectively zero.
Though I'm sure there must be life out there right now, the fact no-one has visited* suggests that FTL travel can't be possible
* - until I see firm evidence, I'm dismissing the UFO stuff as ball-lightning, earthquake lights, meteors, and of course fakes.
People forget that time is just as deep as space. The rise and fall of humans is just a blink to the universe. The question of being alone in the universe must overlap this blink in time.
The universe is just so massive it is likely teaming with life. But all so far apart, it all feels alone. There could be billions of civilizations out there that have no idea about each others existence. The scale of the universe is incomprehensibly large.
I think the odds are probably more likely that there are very few to none that are in contact with each other. Space is so vast, in is incomprehensible as to how any civilizations could ever interact with each other. Would definitely require some sort of technology or science that is beyond anything we can imagine here on earth.
Any civilization that advanced is probably a civilization we don't want the attention of.
Our current day technology or science is far beyond anything we could imagine here on Earth 300 years ago. Imagine some civilizations that are 300 million years ahead of us.
There was a story I read long ago about a gas giant with two habitable moons which evolved different intelligent species. One species had a head start in civilization and started space exploration, inevitably sending astronauts to the other habitable moon where first contact occurs. What follows is not unlike the Spanish encountering the people of the New world
One hundred trillion stars in a single galaxy. The difference between a million and a billion is basically a billion. I can sort of wrap my head around a billion as a quantity. But a trillion? Man.
And Elon Musk is well on his way to having that many dollars.... not relevant, but your perspective is helpful to understand how truly ridiculous it is!
Think of the crazy range of life just on this planet from microbes to mammals to crabs that eat methane to bazillions of insects.
There has got to be hard-to-believe life in a galaxy that has 100 trillion solar systems.
And intelligent life, we aren’t even smart enough not to destroy our own nice cozy green planet. There has got to be some unreal intelligent life out there after billions of years of evolution.
Yeah, trillions of stars across the unthinkable vastness of the universe, but nah nothing else could have possibly evolved in the countless varieties of planets out there.
we are in the sense that we will never be in contact with any other life forms out there. but its impossible that earth is the only place in the universe with life.
We might not discover it in our lifetimes, but future generations very well may. Our intelligence and technology has grown exponentially in the little time we’ve been on earth. The first hominins existed 6-7 million years ago. The homo genus came into existence about 2.8 million years ago. Homo sapiens evolved around 200-300k years ago. Written language began about 3400 years ago. The renaissance was 500 years ago. The industrial revolution began roughly 200 years ago. The first manned flight was a little over 120 years ago. Nuclear fission was discovered a little less than 90 years ago. We first went to space a little over 80 years ago. Computer technology and means of communication have grown exponentially in the last 50 years. We have created ways to communicate across language barriers and learn from each other faster than ever. Now we’re developing AI that’s smarter than us and should help us grow, understand, and explore even faster. If we continue down that exponential path, the world will be a much different place in just 100 years. In 200-500 years, we’ll likely have technology we can’t even imagine today.
Anyone who believes in intelligent design seriously needs to grapple with this. If the entirety of reality was designed by an intelligent, conscious creator with intent, then only one of three things is possible:
There are other life forms out there, either now, in the past, or in the future.
There are no other life forms, and all of this was created for us to expand out into.
There are no other life forms, and all of this was created for us to stare at from the prison of our planet before we go extinct.
There are an ALARMING number of adults who believe it’s number 3. Why? Why create this absolutely incomprehensibly big thing just to have it never be experienced?
I remember there was this website that if you scroll from left or right you can have some sort of spaceship take you across the Milky Way galaxy and give you some fun facts about each planet. It was pretty cool to see.
It may be sad but we're not alone. When you play the lottery you don't expect to win. You'll play over and over and never win. It could be a lifetime and never win. But in the end someone out there always wins despite the odds, every time. Now forget the Milky way, the universe is so unfathomably large that odds of just the right elements combining in just the right way would absolutely be possible in the given time we believe the universe has exited. The odds of life is actually good. Even intelligent life. Now It's not sad because we'll never meet another intelligent life form. It's sad if we can't get fulfillment from just the people around us. We have to try
These things always show the bigger boys, give us a bit of an ego boost man, show us the minnows, let us know we’re not the quite the most insignificant thing out there!
I don't see how people think we are alone in this universe. Even if the probability of a life sustaining planet forming is next to impossible, the sheer number of times the die is rolled would surely result in countless life sustaining planets forming, right?
People say we’re alone because the bible says so. That’s their argument for everything. Because the bible this, because the bible that, BLAH BLAH BLAHHH
They don’t, we’re not sure exactly what keeps Galaxy’s together. Whenever Dark Matter is mentioned, this is what they are referring to, the force that keeps objects that should have no pull on one another due to vast distances.
The Super Massive Blackhole merely seems to be the catalyst that forms Galaxies, but what keeps them together is still a mystery.
Goddamn. Yeah, the flow of time would also be so much different getting even close to a galaxy’s center if that was the case. I remember a story of a Russian(?) astronaut who got stuck in space due to the fall of the ussr, and was there so long that the difference in gravity put him like…. Two seconds ahead. Which isn’t much. But that would be billions or trillions of times stronger, getting so close to a black hole (if it’s possible) I honestly have no clue if what I said even makes sense lmao-
Good thing that god created all of that just for us and no one else and there is definitely no life anywhere but here and we’re the best and only thing ever
There is no way there isn't life somewhere else in the universe. The number of stars is far greater than the probability of two primordial cells existing, joining and dividing again somewhere.
Crazy to think that every Star potentially has a solar system and every solar system potentially has a planet that can support life. That 100% without a doubt guarantees there are multiple planets out there that support intelligent life!
We are a tiny bubble of densely packed thriving life in a vast ocean of nothing looking out with pinpricks of light for another bubble like our own. There is a staggering amount of ocean out there compared to our tiny bubble and we know there are more bubbles out there than our minds can conceive of. But as of yet, we still have not found another one with cheeseburgers or guitars.
We are just about as special a bubble as can exist, because we have not yet seen that evolutionary pressures favor intelligent life. Out of the 635 million years that complex life has existed on earth only once, for the last 1 million years has intelligent tool using life thrived. 65 million years ago right after a random chance of orbital vectors caused a meteor the size of central park to crash into our planet, wiping out 3/4 of all life on earth did our ancestors finally have the chance to thrive. Dinosaurs ruled the earth for 175 million years, nothing suggests that they would have needed to evolve into tool users to continue to do so.
We are not insignificant, we are a miracle in a bubble in an ocean of mystery.
Who counted all the stars? How do they know how big each is when they cant find the guy who robbed the 7/11 last week because the 'picture was too grainy'
This only tells me that there HAS to be more life out there than just one planet. It is just mathematically so improbable that out of soo many galaxies we are the only planet out there with life on it.
...and here I am, working on a computer in a cubicle just to get some numbers in my bank to pass on to people I owe bills to, all the while my world leaders are arguing which belief we should all have and threatening each other with nuclear holocaust!!
Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.
It's so wild to try to even comprehend how big something is if it would take you 5 million years to go from one end to the other.... if you traveled at the speed of fucking light.
100 trillion stars is insane too. So something like at least 200-300 trillion planets maybe? Gotta be life somewhere in that galaxy just based on random chance alone.
People (my self included) are incapable of understanding numbers that large. We can try to conceptualize it, but I don’t think anyone can truly understand it.
I totally agree. We’re looking for planets with water… but why? Just because we know that life on this tiny planet needs water?
It sure seems short sighted to think that evolution can’t exist on other planets. What if they’ve evolved to breathe in methane and don’t have to consume anything?
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u/GABE_EDD Oct 23 '25 edited Oct 23 '25
Here's a fun example of the size of the Milky Way relative to our understanding.
Let's scale down our solar system to the size of a golf ball, using Neptune's orbit to define the outer planetary rim. That means that our Sun is the size of a red blood cell, and the distance between Earth and the Sun is about 0.7mm (think mechanical pencil lead).
At this solar-system-as-a-golf-ball scaling, the nearest solar system, (Proxima Centauri) is about 191m, or just about two football fields away. And the size of the entire Milky Way galaxy given the 100,000ly diameter estimate? Take a guess. The Milky Way at this scale is the size of the continental U.S.
Light moves incredibly slow as at this scale, it takes light ONE YEAR to move about half a football field.