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Why is there a normal galaxy sitting at the edge of the Universe?

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Re: Why is there a normal galaxy sitting at the edge of the Universe?

#171

Post by vermilingua »

krapp wrote: post #156
Supermancho wrote: post #155

Earlier quoted context omitted.

> Since there's no frame of reference outside the universe That's unknown. The observable universe is all we know for sure and there's evidence that there is both something beyond what we can observe, which conforms to what we know as space and matter, and something beyond that (whatever existed around the big bang locality).

>there's evidence that there is something beyond what we can observe By definition, there can't be. Evidence implies something we can observe, which would mean it isn't beyond the observable universe.

Then explain the Hubble volume: unless you believe the Earth is at the center of the universe, basic reasoning tells you that there is a sphere beyond which is outside our light cone, and yet outside which the universe still exists.

Are you saying the observable universe is bounded to our Hubble volume?

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#172

Post by withinboredom »

skissane wrote: post #161
pvarangot wrote: post #109

Earlier quoted context omitted.

That webpage says a tech demo is due 2024, with launch in 2034 and the constellation would reach 550AU by 2064, so probably a lot of how this will work is still WIP.

The problem with dates like that is they are pure best wishes. They might have funding for a demo in 2024 – although it isn't even clear they've got that yet, it sounds like they may just have funding to develop their proposal further. Even assuming the tech demo is successful, it sounds like they don't even yet have a detailed costed proposal for a 2034 launch, and no idea how likely that it will actually get funded…

> Politicians and bureaucrats want immediate results

This makes me sad. The entire point of Government is to be an enterprise spanning multiple generations.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#174

Post by krapp »

vermilingua wrote: post #171
krapp wrote: post #156

Earlier quoted context omitted.

>there's evidence that there is something beyond what we can observe By definition, there can't be. Evidence implies something we can observe, which would mean it isn't beyond the observable universe.

Then explain the Hubble volume: unless you believe the Earth is at the center of the universe, basic reasoning tells you that there is a sphere beyond which is outside our light cone, and yet outside which the universe still exists. Are you saying the observable universe is bounded to our Hubble volume?

>basic reasoning tells you that there is a sphere beyond which is outside our light cone, and yet outside which the universe still exists.

Of course, but basic reasoning isn't evidence. Again... "evidence" implies something that can be observed, and something that can be observed, by definition, lies within the observable universe.

>Are you saying the observable universe is bounded to our Hubble volume?

I'm saying the observable universe is bounded to what we can observe, and evidence of something beyond the observable universe is a contradiction in terms.

I don't know how I can possibly make it simpler.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#175

Post by mensetmanusman »

tectonic wrote: post #2

Nice gravitational lens observation! We're hoping to use the same technique with the Sun to observe exoplanets by launching a fleet of small satellites to 547 AU (80 billion km / ~3 light days). The craft would sample the distorted Einstein ring around our Sun from that vantage point, then combine and reconstruct an image of the disk of an Earth-like exoplanet up to 100 light-years beyond, at a resolution of 25 kilom…

Wow.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#176

Post by meowface »

Aerroon wrote: post #159
meowface wrote: post #137

Earlier quoted context omitted.

From my layman's perspective, I think this is plausible, and many physicists seem to agree it's plausible. Maybe another plausible explanation could be the reverse: maybe before the Big Bang, our/the universe was in the state you describe, and the Big Bang is our perception of it "snapping back" and exploding violently outward (aka a white hole). Carlo Rovelli and others propose that black holes actually only appear…

> So under this hypothesis, a black hole never reaches a true singularity, but as close to a singularity as physically possible, and then it almost instantaneously bounces back like a taut rubber band that's stretched back as far as it'll go. Kind of like a graph of 1/x, where everything behaves predictably, but there's that one point that doesn't fit?

I'm absolutely terrible and uneducated when it comes to math, so I'm not sure exactly what you mean. But if you mean 1/x where x = infinity, then yes, the classical idea of a singularity (such as what's been theorized to exist within a black hole, curving to an infinitely small point) is basically like 1/infinity or dividing by zero.

Rovelli hypothesizes this never actually happens and is not physically possible, and rather, when the most physically extreme possible level of curvature does occur, it "snaps back". If true, this ensures black holes do actually behave predictably, and physics doesn't actually break down; it just gets as extreme as it can possibly get.

So under this hypothesis, x gets really high, but the universe prevents it from ever reaching infinity. This would also potentially resolve some paradoxes related to black holes.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#177

Post by throwaway568 »

dumpsterdiver wrote: post #67
zemnmez wrote: post #59

Earlier quoted context omitted.

this is because things aren’t ‘moving apart’— space itself is expanding (into what? nobody knows). it’s not that the galaxies are being propelled apart from a force in a particular place either; everything is expanding away from everything else . On the traditional balloon model, the surface of the balloon represents space itself. Those dots on the surface of an expanding balloon are not moving relative to space (the…

>"space itself is expanding (into what? nobody knows)" I have a terrifying theory on this (granted, the Earth will be long gone). What if the universe is not actually expanding in the sense that it is being propelled by an initial explosion, but instead falling towards a much greater mass - the end of time so to speak, where all mass ends. Considering that gravity is a "weak force", the scale of such a mass makes me…

Interesting, this adds to a thought I had a couple of weeks ago.

We can see the past, but we can’t go there, like an observer inside event horizon looking out, they can see light coming in, but can’t leave.

We can’t see the future, but when we are going there, like an observer falling into the event horizon. They can’t see what’s inside, but they can fall inside.

As we experience time, it’s like we are falling into a black hole made of time.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#178

Post by mensetmanusman »

vermilingua wrote: post #171
krapp wrote: post #156

Earlier quoted context omitted.

>there's evidence that there is something beyond what we can observe By definition, there can't be. Evidence implies something we can observe, which would mean it isn't beyond the observable universe.

Then explain the Hubble volume: unless you believe the Earth is at the center of the universe, basic reasoning tells you that there is a sphere beyond which is outside our light cone, and yet outside which the universe still exists. Are you saying the observable universe is bounded to our Hubble volume?

Wouldn’t that be interesting...

great sci fi plot, the earth is the center of the universe because anything out side of our sphere can’t be observed by our consciousness and ‘collapse’ into existence :)

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#179

Post by codeulike »

meowface wrote: post #137
dumpsterdiver wrote: post #67

Earlier quoted context omitted.

>"space itself is expanding (into what? nobody knows)" I have a terrifying theory on this (granted, the Earth will be long gone). What if the universe is not actually expanding in the sense that it is being propelled by an initial explosion, but instead falling towards a much greater mass - the end of time so to speak, where all mass ends. Considering that gravity is a "weak force", the scale of such a mass makes me…

From my layman's perspective, I think this is plausible, and many physicists seem to agree it's plausible. Maybe another plausible explanation could be the reverse: maybe before the Big Bang, our/the universe was in the state you describe, and the Big Bang is our perception of it "snapping back" and exploding violently outward (aka a white hole). Carlo Rovelli and others propose that black holes actually only appear…

See also Magnetospheric Eternally Collapsing Object for another no-singularity theory of Black Holes

https://en.wikipedia.org/wiki/Magnetospheric_eternally_colla...

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#180

Post by mensetmanusman »

ddevault wrote: post #70
zemnmez wrote: post #59

Earlier quoted context omitted.

this is because things aren’t ‘moving apart’— space itself is expanding (into what? nobody knows). it’s not that the galaxies are being propelled apart from a force in a particular place either; everything is expanding away from everything else . On the traditional balloon model, the surface of the balloon represents space itself. Those dots on the surface of an expanding balloon are not moving relative to space (the…

In case anyone is confused, I prefer to explain the expansion of space without metaphors. Space itself is getting larger, everywhere, all at once. The scale factor of the universe is getting larger. New space is constantly being "made". Every second, every kilometer in the universe grows by 2.2×10^-18 centimeters. If no other forces were in play, it'd carry everything along with it and pull everything a bit further a…

Do particles in this model re-adjust their spacing to the new space being created?

e.g. after 10^18 seconds, would the diameter of a hydrogen atom still be the same? or is it scaled to be huge (relative to now) ?

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