Starship Asterisk*

Christian G. wrote: ↑Fri Jul 05, 2024 1:38 pm

Chris Peterson wrote: ↑Wed Jul 03, 2024 3:55 am

Avalon wrote: ↑Wed Jul 03, 2024 2:40 am What kind of explanation is "before" not having any meaning in the context of the universe? The entire illustration is a timeline of the universe.

That doesn't mean there's a "before". That word is pretty hard to define when time doesn't exist.

I'm reminded of the "What did God do before creating the Universe? He was preparing Hell for those who would ask!"
We can’t ask what was going on during the time when time did not exist - obviously. My question is: How do you ask the question? What is the correct choice of words?
Before, there was no before, fair enough. But that doesn’t mean it was nothingness.... Did the Big Bang result from a quantic fluctuation, was it a violent transition between two different states of the universe or whatever other speculation misguided or not, whatever the unknowable answer, - how do you merely formulate the question of the "upstream"of the Big Bang?

Chris Peterson wrote: ↑Wed Jul 03, 2024 3:55 am

Avalon wrote: ↑Wed Jul 03, 2024 2:40 am What kind of explanation is "before" not having any meaning in the context of the universe? The entire illustration is a timeline of the universe.

That doesn't mean there's a "before". That word is pretty hard to define when time doesn't exist.

Avalon wrote: ↑Wed Jul 03, 2024 2:40 am What kind of explanation is "before" not having any meaning in the context of the universe? The entire illustration is a timeline of the universe.

Avalon wrote: ↑Tue Jul 02, 2024 2:11 am So, so many questions. What IS outside of time, like before the BB? How is it that humans existed for millions of years and the formation of cities only during the last 10,000 years? Were they without any intelligence or social skills before that? How convinced are we about the Theia event? How are events taking billions of years even calculated time-wise? Etc., etc.

johnnydeep wrote: ↑Mon Jul 01, 2024 11:04 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 6:15 pm

johnnydeep wrote: ↑Mon Jul 01, 2024 5:56 pm

Sure, but it must be possible to compare the two opposing forces operating between my two protons. But I suppose in retrospect, that in isolated space, it would take much more than a 1 meter spatial separation for dark energy to overcome the mutual attraction between them. I'm still interested in the quantities though.

Well, to further complicate things, the "force" of gravity is the product of a distortion of spacetime created by mass. That makes two masses want to "fall" towards each other. But dark energy isn't a distortion, because it is uniform. It doesn't care about mass (so it isn't like anti-gravity). It is just a steady expansive pull on all of spacetime. But spacetime can't expand against strong gravitational attraction (which is why galaxies and galaxy clusters are not getting larger or separating). Spacetime is held together locally by gravity. The gravitational attraction of a couple of protons (lets make them neutrons, okay... don't need to add EM forces to this problem) is extremely small, so if you could somehow get those particles isolated enough (or just take it as a thought experiment where they are the only things in the Universe), there will be some distance where dark energy dominates gravity. I wouldn't be surprised if it was a very small distance. But I don't know.

(Yeah, neutrons, except isolated neutrons are unstable. But I guess that doesn't matter for this thought experiment.)

I'm surprised you'd think that (in blue). But surely, this should be calculable based on the Hubble constant?

And one more thought: if dark energy content depends on the "amount" of space, what about when space is compressed in a black hole - does that concentrate the dark energy and result in a greater repulsive force?

Chris Peterson wrote: ↑Mon Jul 01, 2024 6:15 pm

johnnydeep wrote: ↑Mon Jul 01, 2024 5:56 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 5:48 pm
"Stronger" and "weaker" is probably not the best way to think of it. The force of gravity falls of with distance, while the force of dark energy, while very small, is uniform across all of space. So it dominates when space is nearly empty of mass, which only occurs over cosmological distances.

Sure, but it must be possible to compare the two opposing forces operating between my two protons. But I suppose in retrospect, that in isolated space, it would take much more than a 1 meter spatial separation for dark energy to overcome the mutual attraction between them. I'm still interested in the quantities though.

Well, to further complicate things, the "force" of gravity is the product of a distortion of spacetime created by mass. That makes two masses want to "fall" towards each other. But dark energy isn't a distortion, because it is uniform. It doesn't care about mass (so it isn't like anti-gravity). It is just a steady expansive pull on all of spacetime. But spacetime can't expand against strong gravitational attraction (which is why galaxies and galaxy clusters are not getting larger or separating). Spacetime is held together locally by gravity. The gravitational attraction of a couple of protons (lets make them neutrons, okay... don't need to add EM forces to this problem) is extremely small, so if you could somehow get those particles isolated enough (or just take it as a thought experiment where they are the only things in the Universe), there will be some distance where dark energy dominates gravity. I wouldn't be surprised if it was a very small distance. But I don't know.

johnnydeep wrote: ↑Mon Jul 01, 2024 5:56 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 5:48 pm

johnnydeep wrote: ↑Mon Jul 01, 2024 5:31 pm

So this question just occurred to me: how much weaker (or stronger) is dark energy compared to gravity? Say, given two protons separated by a meter, how does their mutual attraction due to gravity compare to the dark energy expansion force due to the spatial separation between them?

"Stronger" and "weaker" is probably not the best way to think of it. The force of gravity falls of with distance, while the force of dark energy, while very small, is uniform across all of space. So it dominates when space is nearly empty of mass, which only occurs over cosmological distances.

Sure, but it must be possible to compare the two opposing forces operating between my two protons. But I suppose in retrospect, that in isolated space, it would take much more than a 1 meter spatial separation for dark energy to overcome the mutual attraction between them. I'm still interested in the quantities though.

Chris Peterson wrote: ↑Mon Jul 01, 2024 5:48 pm

johnnydeep wrote: ↑Mon Jul 01, 2024 5:31 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 5:18 pm

This is the point where the expansion rate of the Universe transitioned from slowing to speeding up. Where the "force" of dark energy became greater than the "force" of gravity.

So this question just occurred to me: how much weaker (or stronger) is dark energy compared to gravity? Say, given two protons separated by a meter, how does their mutual attraction due to gravity compare to the dark energy expansion force due to the spatial separation between them?

"Stronger" and "weaker" is probably not the best way to think of it. The force of gravity falls of with distance, while the force of dark energy, while very small, is uniform across all of space. So it dominates when space is nearly empty of mass, which only occurs over cosmological distances.

johnnydeep wrote: ↑Mon Jul 01, 2024 5:31 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 5:18 pm

zendae wrote: ↑Mon Jul 01, 2024 5:06 pm "Dark energy overtakes gravity."

Is this because gravity was universally weak at this stage due to less matter? I am not sure what exactly this statement really implies. What would be the difference between the Universe with no dark energy and the Universe after dark energy "overtook" gravity? I know that gravity is far, far, far weaker than the strong force, yet virtually nothing - perhaps absolutely nothing - overtakes gravity at a certain point. The term "overtakes" in the quote has me.

This is the point where the expansion rate of the Universe transitioned from slowing to speeding up. Where the "force" of dark energy became greater than the "force" of gravity.

So this question just occurred to me: how much weaker (or stronger) is dark energy compared to gravity? Say, given two protons separated by a meter, how does their mutual attraction due to gravity compare to the dark energy expansion force due to the spatial separation between them?

ww1y wrote: ↑Mon Jul 01, 2024 2:43 pm "Within a few billion years, atoms formed," while technically correct, is somewhat misleading. Unless JADES-GS-z14-0 is made up of something other than atoms?

Chris Peterson wrote: ↑Mon Jul 01, 2024 5:18 pm

zendae wrote: ↑Mon Jul 01, 2024 5:06 pm "Dark energy overtakes gravity."

Is this because gravity was universally weak at this stage due to less matter? I am not sure what exactly this statement really implies. What would be the difference between the Universe with no dark energy and the Universe after dark energy "overtook" gravity? I know that gravity is far, far, far weaker than the strong force, yet virtually nothing - perhaps absolutely nothing - overtakes gravity at a certain point. The term "overtakes" in the quote has me.

This is the point where the expansion rate of the Universe transitioned from slowing to speeding up. Where the "force" of dark energy became greater than the "force" of gravity.

zendae wrote: ↑Mon Jul 01, 2024 5:06 pm "Dark energy overtakes gravity."

Is this because gravity was universally weak at this stage due to less matter? I am not sure what exactly this statement really implies. What would be the difference between the Universe with no dark energy and the Universe after dark energy "overtook" gravity? I know that gravity is far, far, far weaker than the strong force, yet virtually nothing - perhaps absolutely nothing - overtakes gravity at a certain point. The term "overtakes" in the quote has me.

Chris Peterson wrote: ↑Mon Jul 01, 2024 4:31 pm

johnnydeep wrote: ↑Mon Jul 01, 2024 4:27 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 4:24 pm
Electromagnetic radiation isn't the only medium we have for observation. Gravity waves (which we are increasingly able to detect) might provide a way of looking at the Universe during a time when it was optically opaque.

Ok, thanks. I always seem to forget about gravitational waves (note: not gravity waves which are about fluid dynamics).

Yes, gravitational waves. Who knows with what resolution and sensitivity we'll eventually be able to measure them, even to image with them. And I wonder about particles like neutrinos or dark matter, which might be unaffected by passing through neutral hydrogen. Lacking the technology, at the moment, to observe the dark ages doesn't mean they aren't observable.

johnnydeep wrote: ↑Mon Jul 01, 2024 4:27 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 4:24 pm

johnnydeep wrote: ↑Mon Jul 01, 2024 4:22 pm

What do you mean by being "in principle observable"? (assuming the "dark ages" was the period of time from the BB to about 380,000 years when photons were freed to travel)

Electromagnetic radiation isn't the only medium we have for observation. Gravity waves (which we are increasingly able to detect) might provide a way of looking at the Universe during a time when it was optically opaque.

Ok, thanks. I always seem to forget about gravitational waves (note: not gravity waves which are about fluid dynamics).

Chris Peterson wrote: ↑Mon Jul 01, 2024 4:24 pm

johnnydeep wrote: ↑Mon Jul 01, 2024 4:22 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 3:41 pm
The Big Bang is not a hypothesis, it is a theory, and one which is well supported by multiple independent lines of objective evidence. The existence of inflation is similarly well supported, and doesn't violate any physical principles. We observe the CMB (which I assume is what you mean), and while we can't observe the "dark ages" in the electromagnetic spectrum, it is in principle observable. Our understanding of the formation of stars and galaxies is unlikely to be "wrong", simply incomplete.

...

What do you mean by being "in principle observable"? (assuming the "dark ages" was the period of time from the BB to about 380,000 years when photons were freed to travel)

Electromagnetic radiation isn't the only medium we have for observation. Gravity waves (which we are increasingly able to detect) might provide a way of looking at the Universe during a time when it was optically opaque.

johnnydeep wrote: ↑Mon Jul 01, 2024 4:22 pm

Chris Peterson wrote: ↑Mon Jul 01, 2024 3:41 pm

Syringa vulgaris wrote: ↑Mon Jul 01, 2024 3:36 pm Really, now?

We don't know if there was a big bang, it is a hypothesis without any evidence to support it.

We have no idea what is this "inflation", except we know it must have violated all assumptions that are the foundation of modern physics.

We have no idea how things were in the part that says "SMB" and "dark ages".

Our current beliefs about the timeline of the appearance of stars and galaxies, the very first thing we can actually measure, appear to be very wrong.

Most of the remaining "spiral" (the outer 3 rings or so) is concerned with very local phenomena compared to what we believe is the size of the visible Universe.

And even there we can't see 80% of the phenomenon that acts on the visible stuff through gravity.

But yeah, let's pretend we can answer a question like "What's happened since the universe started?".

We can hypothesize, and make some claims about a small part of the Universe, but that's about all.

We know a few things, but let's not pretend a whole lot is set in stone.

The Big Bang is not a hypothesis, it is a theory, and one which is well supported by multiple independent lines of objective evidence. The existence of inflation is similarly well supported, and doesn't violate any physical principles. We observe the CMB (which I assume is what you mean), and while we can't observe the "dark ages" in the electromagnetic spectrum, it is in principle observable. Our understanding of the formation of stars and galaxies is unlikely to be "wrong", simply incomplete.

...

What do you mean by being "in principle observable"? (assuming the "dark ages" was the period of time from the BB to about 380,000 years when photons were freed to travel)

Chris Peterson wrote: ↑Mon Jul 01, 2024 3:41 pm

Syringa vulgaris wrote: ↑Mon Jul 01, 2024 3:36 pm Really, now?

We don't know if there was a big bang, it is a hypothesis without any evidence to support it.

We have no idea what is this "inflation", except we know it must have violated all assumptions that are the foundation of modern physics.

We have no idea how things were in the part that says "SMB" and "dark ages".

Our current beliefs about the timeline of the appearance of stars and galaxies, the very first thing we can actually measure, appear to be very wrong.

Most of the remaining "spiral" (the outer 3 rings or so) is concerned with very local phenomena compared to what we believe is the size of the visible Universe.

And even there we can't see 80% of the phenomenon that acts on the visible stuff through gravity.

But yeah, let's pretend we can answer a question like "What's happened since the universe started?".

We can hypothesize, and make some claims about a small part of the Universe, but that's about all.

We know a few things, but let's not pretend a whole lot is set in stone.

The Big Bang is not a hypothesis, it is a theory, and one which is well supported by multiple independent lines of objective evidence. The existence of inflation is similarly well supported, and doesn't violate any physical principles. We observe the CMB (which I assume is what you mean), and while we can't observe the "dark ages" in the electromagnetic spectrum, it is in principle observable. Our understanding of the formation of stars and galaxies is unlikely to be "wrong", simply incomplete.

...

Syringa vulgaris wrote: ↑Mon Jul 01, 2024 3:36 pm Really, now?

We don't know if there was a big bang, it is a hypothesis without any evidence to support it.

We have no idea what is this "inflation", except we know it must have violated all assumptions that are the foundation of modern physics.

We have no idea how things were in the part that says "SMB" and "dark ages".

Our current beliefs about the timeline of the appearance of stars and galaxies, the very first thing we can actually measure, appear to be very wrong.

Most of the remaining "spiral" (the outer 3 rings or so) is concerned with very local phenomena compared to what we believe is the size of the visible Universe.

And even there we can't see 80% of the phenomenon that acts on the visible stuff through gravity.

But yeah, let's pretend we can answer a question like "What's happened since the universe started?".

We can hypothesize, and make some claims about a small part of the Universe, but that's about all.

We know a few things, but let's not pretend a whole lot is set in stone.