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First pictures from Euclid satellite reveal billions of orphan stars

nottingham.ac.uk

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Re: First pictures from Euclid satellite reveal billions of orphan stars

#91
post #70

That's a lot of stars indeed. The human mind cannot even comprehend this number. Not to mention all those planets and moons around those stars

My favorite reply in similar comments is the reference to the total perspective vortex by The Hitchhiker's Guide to the Galaxy:

https://hitchhikers.fandom.com/wiki/Total_Perspective_Vortex

Re: First pictures from Euclid satellite reveal billions of orphan stars

#92

So an orphan star is one that's been ejected from its galaxy. If one of those stars had a planet with something capable of "gazing up at the night sky", does that mean their sky would be empty compared to our own?

No, their night sky would be more or less like our own. There would be other stars and galaxies visible, it's just that this planet (along with the other planets of this orphan star) would be outside of a galaxy and they would be travelling the universe in the "void" between galaxies. Being outside a galaxy doesn't mean that you have a black night sky, it just means that you're a little bit further away from other st…

We can see the Milky Way in clear conditions; with light pollution we can only see the brightest stars. Perhaps an orphan star would have a darker sky, without a clear view of a galactic superstructure without using a telescope?

Re: First pictures from Euclid satellite reveal billions of orphan stars

#93

I really find hard to believe how people can say "well, maybe it's not that easy to have other forms of life in the Universe". I mean, we have a cluster with thousands of galaxies, which make it for millions of stars, 240 MILLION light years away. Which means that there is a 240 million years window in which we are basically blind. Any communication from there will never reach the human race, most probably. Philosoph…

If the universe is infinite like we think it is, then there is life somewhere, in fact, there is an infinite number of copies the earth exactly like or own, with a copy of you and me on it. We are just "blinded" by the limits of the observable universe.

So, we are almost 100% sure that there is extraterrestrial life somewhere in the universe, but if there is no possible causal relationship between us, what's the point? It is also the same reason why "the universe" is often shorthand for "the observable universe". There is probably something beyond it, but we have no way to know what it is, so it might as well not exist.

Re: First pictures from Euclid satellite reveal billions of orphan stars

#94
post #93

I really find hard to believe how people can say "well, maybe it's not that easy to have other forms of life in the Universe". I mean, we have a cluster with thousands of galaxies, which make it for millions of stars, 240 MILLION light years away. Which means that there is a 240 million years window in which we are basically blind. Any communication from there will never reach the human race, most probably. Philosoph…

If the universe is infinite like we think it is, then there is life somewhere, in fact, there is an infinite number of copies the earth exactly like or own, with a copy of you and me on it. We are just "blinded" by the limits of the observable universe. So, we are almost 100% sure that there is extraterrestrial life somewhere in the universe, but if there is no possible causal relationship between us, what's the poin…

I am not aware of any models of the universe that posit an infinite mass.

Edit: Also, "observable universe" is a frequently misunderstood concept. Just because something is now outside the observable universe (the distance between them and us is big enough so that the rate of expansion of the universe between us and them is higher than the speed of light) doesn't mean that we aren't, today, receiving light from a long time ago when the object was closer. If you go far enough back in time you can "see" the entire universe . As time passes, more and more mass moves outside of the observable universe since the size of the sphere is constant relative to the rate of expansion.

Re: First pictures from Euclid satellite reveal billions of orphan stars

#95
post #93

I really find hard to believe how people can say "well, maybe it's not that easy to have other forms of life in the Universe". I mean, we have a cluster with thousands of galaxies, which make it for millions of stars, 240 MILLION light years away. Which means that there is a 240 million years window in which we are basically blind. Any communication from there will never reach the human race, most probably. Philosoph…

If the universe is infinite like we think it is, then there is life somewhere, in fact, there is an infinite number of copies the earth exactly like or own, with a copy of you and me on it. We are just "blinded" by the limits of the observable universe. So, we are almost 100% sure that there is extraterrestrial life somewhere in the universe, but if there is no possible causal relationship between us, what's the poin…

> If the universe is infinite like we think it is, then there is life somewhere, in fact, there is an infinite number of copies the earth exactly like or own, with a copy of you and me on it.

This requires more assumptions than just infinite scale.

Re: First pictures from Euclid satellite reveal billions of orphan stars

#96
post #93

I really find hard to believe how people can say "well, maybe it's not that easy to have other forms of life in the Universe". I mean, we have a cluster with thousands of galaxies, which make it for millions of stars, 240 MILLION light years away. Which means that there is a 240 million years window in which we are basically blind. Any communication from there will never reach the human race, most probably. Philosoph…

If the universe is infinite like we think it is, then there is life somewhere, in fact, there is an infinite number of copies the earth exactly like or own, with a copy of you and me on it. We are just "blinded" by the limits of the observable universe. So, we are almost 100% sure that there is extraterrestrial life somewhere in the universe, but if there is no possible causal relationship between us, what's the poin…

this is such a commonly-repeated fallacy. just because something is infinite, doesn't mean everything is possible. the sequence 1,3,5,7,9,... is infinite, and yet it contains no even numbers. there are many such cases.

Re: First pictures from Euclid satellite reveal billions of orphan stars

#97
post #94
post #93

Earlier quoted context omitted.

If the universe is infinite like we think it is, then there is life somewhere, in fact, there is an infinite number of copies the earth exactly like or own, with a copy of you and me on it. We are just "blinded" by the limits of the observable universe. So, we are almost 100% sure that there is extraterrestrial life somewhere in the universe, but if there is no possible causal relationship between us, what's the poin…

I am not aware of any models of the universe that posit an infinite mass. Edit: Also, "observable universe" is a frequently misunderstood concept. Just because something is now outside the observable universe (the distance between them and us is big enough so that the rate of expansion of the universe between us and them is higher than the speed of light) doesn't mean that we aren't, today, receiving light from a lon…

That would imply there’s an edge to be closer to, which doesn’t align with my understanding of it.

Re: First pictures from Euclid satellite reveal billions of orphan stars

#98
post #93

Earlier quoted context omitted.

If the universe is infinite like we think it is, then there is life somewhere, in fact, there is an infinite number of copies the earth exactly like or own, with a copy of you and me on it. We are just "blinded" by the limits of the observable universe. So, we are almost 100% sure that there is extraterrestrial life somewhere in the universe, but if there is no possible causal relationship between us, what's the poin…

> If the universe is infinite like we think it is, then there is life somewhere, in fact, there is an infinite number of copies the earth exactly like or own, with a copy of you and me on it. This requires more assumptions than just infinite scale.

Right, like in math, not all infinite sequences contain every finite subsequence. For example, a non-repeating sequence of 2's and 7's contains no sequence "4". The further condition is that the number be normal[1].

Also, TIL we don't know whether π is normal thus the popular claim that "every string of numbers eventually occurs in π" is not known to be true

[1] https://en.wikipedia.org/wiki/Normal_number

Re: First pictures from Euclid satellite reveal billions of orphan stars

#99

I really find hard to believe how people can say "well, maybe it's not that easy to have other forms of life in the Universe". I mean, we have a cluster with thousands of galaxies, which make it for millions of stars, 240 MILLION light years away. Which means that there is a 240 million years window in which we are basically blind. Any communication from there will never reach the human race, most probably. Philosoph…

People underestimate how dead and hostile the space is to life in general. First of all, you can just swipe most of the available galaxy space off the table because of radiation - the center of the Milky Way, close to our "core" black hole, is just pure hell. This is why we inhabit a remote neighborhood of the galaxy. You can extrapolate that most spiral galaxies are like that and only a small sliver of them are "in play".

Earth won multiple jackpot lotteries in a row, and that's only the variables we are aware of:

* Right-sized star

* Right-sized planet

* Not too far and not to close to the star

* Not too little and not too much water

* Oxygen

* Iron core (magnetic field protects from radiation)

* Right-sized moon (keeps rotation stable, tides)

* Gas giants absorbing a lot of debris coming our away

* A single-star system, with nearly circular, stable planetary orbits (very rare)* ... and so on

Yes, I know there are permutations that might also work, but in general it does not look good for spontaneous life.I like a theory that states that the Universe is just the right size where one single Earth has only a single probability to spring up randomly. The Maker covered their tracks well, if you believe in higher intelligence.

Re: First pictures from Euclid satellite reveal billions of orphan stars

#100

So an orphan star is one that's been ejected from its galaxy. If one of those stars had a planet with something capable of "gazing up at the night sky", does that mean their sky would be empty compared to our own?

No, their night sky would be more or less like our own. There would be other stars and galaxies visible, it's just that this planet (along with the other planets of this orphan star) would be outside of a galaxy and they would be travelling the universe in the "void" between galaxies. Being outside a galaxy doesn't mean that you have a black night sky, it just means that you're a little bit further away from other st…

So my understanding is most of the stars that fill our sky are stars inside our milky way and nearby. "The Milky Way" smudge we can see in a dark sky is the collective effort of all the far-off milky way stars.

I assume some of the 'stars' we can see with the naked eye are actually galaxies, but I assume that's a small percentage.

Our closest galaxy, Andromeda, appears barely as a smudge to the naked eye.

I guess my question is more about how far away from their home galaxies are these orphan stars, expressed as a percentage of a hypothetical planet's sky-cover.

eg we see the milky way as a band because we're inside the galactic plane... would these orphan planets see their home galaxy as a fainter band because they've been ejected still in the galactic plane? Would they see part of the sky covered and part of the sky blank because they're outside their home galactic plane? Are they still close enough to their home galaxy that they're still surrounded by enough stars to fill the sky, or would the star density in their skies be seasonal?

I think it would be fun to speculate on different hypothetical cultural evolutions of different kinds of night sky configurations, like "winter is when our planet's night sees our home galaxy, so winter is when the gods send their nightlumination down on us" etc.

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