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The universe is expanding faster than expected

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Re: The universe is expanding faster than expected

#151

Post by atomi »

taude wrote: post #127

If you're finding this interesting, I recently discovered this YouTube channel on How Far Away Is It [1]. There's a few different playlists of what he calls digital books, that are all worth watching for a novice: How Far Away is It? [2]; How Small is It [3]; How Fast is It [4] As a side benefit, it can be soothing and nap inducing, but in the best ways. It's taken a couple attempts to get through some of the episode…

There is also one of my favorite talks tangentially related by Lawrence Krauss. He explains that eventually a civilization exploring the universe around them will only see it's own galaxy and likely believe that's all there is. We are living in an extraordinary time where we are still able to see other galaxies.

https://www.youtube.com/watch?v=7ImvlS8PLIo

Re: The universe is expanding faster than expected

#153

Post by dragonwriter »

drukenemo wrote: post #143
chanakya wrote: post #126

Can someone explain why the universe is expanding at all? I've heard it said "it's the momentum from the Big Bang". That sounds reasonable, but then we're told that it's not that the galaxies are flying apart, it's that the "basic metric of space itself is expanding". I can understand momentum from an explosion, but why would "space itself" expand because of an explosion?

I’m amazed how the God hypothesis seems to not exist amongst the modern, smart tech world. Everything is science, science one day will know...

> I’m amazed how the God hypothesis seems to not exist amongst the modern, smart tech world.

God is not a hypothesis, but more of an theory in the analytical rather than scientific sense. That is, God is a conceptual framework by through which other information is interpreted, not a source of testable predictions.

Re: The universe is expanding faster than expected

#154

Post by est31 »

atomi wrote: post #151
taude wrote: post #127

If you're finding this interesting, I recently discovered this YouTube channel on How Far Away Is It [1]. There's a few different playlists of what he calls digital books, that are all worth watching for a novice: How Far Away is It? [2]; How Small is It [3]; How Fast is It [4] As a side benefit, it can be soothing and nap inducing, but in the best ways. It's taken a couple attempts to get through some of the episode…

There is also one of my favorite talks tangentially related by Lawrence Krauss. He explains that eventually a civilization exploring the universe around them will only see it's own galaxy and likely believe that's all there is. We are living in an extraordinary time where we are still able to see other galaxies. https://www.youtube.com/watch?v=7ImvlS8PLIo

I can imagine scientists in a couple billion years debating whether the historic records of other galaxies existing should be believed or whether one should dismiss them as crazy religious texts someone faked a couple million years ago...

(obviously by then we'll probably uploaded ourselves to computers and turned into totally different beings from what we are now, but the problem of trusting historic data still exists)

Re: The universe is expanding faster than expected

#155

Post by ravi-delia »

Rexxar wrote: post #140
chanakya wrote: post #126

Can someone explain why the universe is expanding at all? I've heard it said "it's the momentum from the Big Bang". That sounds reasonable, but then we're told that it's not that the galaxies are flying apart, it's that the "basic metric of space itself is expanding". I can understand momentum from an explosion, but why would "space itself" expand because of an explosion?

Science ultimately never answer to "why?" but to "how?". Science give us a model to describe universe but won't tell you why it exists.

While it seems that might be true of whatever the bottom level is, we're nowhere near that now. For instance, we know not just the how but why of Newtonian gravity; relavistic gravity! Of course, we have lots of unknowns about relavistic gravity, so on it goes.

Re: The universe is expanding faster than expected

#156

Post by grishka »

pdonis wrote: post #115
grishka wrote: post #109

> It would be incredibly exciting if there was new physics It would indeed be incredibly exciting if it would lead to a less silly explanation of the redshift than "universe is expanding".

> It would indeed be incredibly exciting if it would lead to a less silly explanation of the redshift than "universe is expanding". It won't. There is no question about whether the universe is expanding. The issue is over how fast it is expanding; we have two different theoretical models that are giving different answers, and we don't understand (yet) how to reconcile them.

> There is no question about whether the universe is expanding.

Why?

> we have two different theoretical models that are giving different answers, and we don't understand (yet) how to reconcile them.

Maybe... just maybe... that's because it isn't actually expanding, but there's some other, unknown effects at play?

It's about time we think outside the box. To me, as a regular programmer kind of person, the very idea that the universe is expanding makes about as much sense as dark matter. I get it, both make the calculations work out, but they're basically "we have no clue what this actually is, here's our best guess" kind of variable.

Re: The universe is expanding faster than expected

#157

Post by cambalache »

chanakya wrote: post #126

Can someone explain why the universe is expanding at all? I've heard it said "it's the momentum from the Big Bang". That sounds reasonable, but then we're told that it's not that the galaxies are flying apart, it's that the "basic metric of space itself is expanding". I can understand momentum from an explosion, but why would "space itself" expand because of an explosion?

You have to differentiate 2 things.

The expansion of the universe, which is known since Hubble observations.Although interesting, it can be explained assuming the big bang (a big assumption of course, but with plenty of experimental evidence).

The second thing,, and the truly mind-blowing one, it is that not only the universe is expanding, but that the expansion is accelerating!! The usual date for this discovery is 1998. This is like throwing a baseball upwards and instead of it keeping its speed or de-accelarating (because of gravity and friction) the ball instead starts to move faster and faster. You would suspect the existence of an unknown energy that is powering this acceleration. That is what is called dark energy , which for all intents and purposes it is a giant black box with a question mark right now.

Re: The universe is expanding faster than expected

#158

Post by type_enthusiast »

dheera wrote: post #147
7373737373 wrote: post #5

Here's a narrated video about this current cosmological crisis: https://www.youtube.com/watch?v=0sfvQ_fsil4 This is one of the key graphics: https://i0.wp.com/particlebites.com/wp-content/uploads/2020/...

The biggest "concern" I have about the expanding universe is that although I have a lot of hope for interstellar travel at some point in the coming few millenia, intergalactic travel poses a whole another set of impossibilities to face, that I'm worried it will never be possible. The space between galaxies is pretty devoid of anything you can use as fuel, repair materials, or anything else. That space is expanding, a…

Well, that puts some perspective on 2020.

I mean, it's bleak perspective, but surely if we all write to our congressperson we can act now to prevent the heat death of the universe, right?

Re: The universe is expanding faster than expected

#159

Post by lisper »

User23 wrote: post #150
lisper wrote: post #134

Earlier quoted context omitted.

> physics is a laboratory science That would come as news to most theoretical physicists, who rarely set foot in a laboratory. > we can ... produce quarks How do you know we can produce quarks? Also, where does astronomy fit into your taxonomy? Was Newton doing science or phenomenology when he came up with the inverse square law? Plate tectonics? What about (drum roll, please) biology?

> That would come as news to most theoretical physicists, who rarely set foot in a laboratory. I agree that it's fair to describe cosmologists as a species of theoretical physicist, given the long standing connection between the observation of heavily bodies and the birth of the modern physical sciences. Still the relation is rather remote. > How do you know we can produce quarks? I personally don't. I'm relying on h…

> Astronomy is a phenomenology

OK, again this would come as a surprise to most astronomers. Are you aware that we have sent spacecraft to other planets, and that humans have walked on the moon?

Re: The universe is expanding faster than expected

#160

Post by [deleted] »

rytill wrote: post #20
xwdv wrote: post #13

Earlier quoted context omitted.

The worry is that not only will we be utterly destroyed, but that the destruction will be so thorough it will blow backward through time erasing all events that ever happened and making it so that we never even lived. That means everything we experience right now didn’t happen, we are just seeing a probability of what could happen but didn’t because it’s all destroyed. These lives mean nothing.

I don't see how it's possible to un-make-something-happen. It already happened. It's gone. You can't kill what's already dead.

[deleted]
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