3 ms·

Seriously, what are you talking about? We know a lot about cosmology. In particular there is very good evidence for for the basic model: hot big bang, cold dar

by weichi 17y ago

Seriously, what are you talking about? We know a lot about cosmology. In particular there is very good evidence for for the basic model: hot big bang, cold dark matter, accelerating expansion, geometrically flat, ~14 billions years old (see http://www.astro.ucla.edu/~wright/cosmology_faq.html http://www.astro.ucla.edu/~wright/cosmology_faq.html for more). Granted we don't know what the dark matter is, and we don't know what's causing the acceleration. Those are big unknowns! But the basic picture is pretty well understood. And I think it's very unlikely that much of this picture is "deeply wrong". I mean, what do you think? Some day we are going to discover that the universe wasn't really denser and hotter in the past? That the universe isn't really expanding? That baryonic matter makes up all of the mass of the universe?

waterlesscloud 17y ago
The very faq you link to uses cautious language. Look at "currently most accepted model" right there in the first question. If you've followed cosmological history at all, it's been a cascading series of big changes decade after decade. I'm virtually certain the model of 2030 will vary in deep, significant ways from the model of 2010.
- weichi 17y ago
  Can you be more specific? What parts of the "hot big bang, cold dark matter, accelerating expansion, geometrically flat, ~14 billion years old" model will be shown to be "deeply wrong"? Do you think that discovering, say, the nature of dark energy, is going to demonstrate that the universe isn't really expanding? That we are going to discover that the universe is really 100 billion years old? That the universe was actually colder and larger in the past?
InclinedPlane 17y ago
You're both correct. We know a lot about cosmology compared to what we knew, say, 100 or especially 200 years ago. Many of the big, open cosmological questions throughout human history (what is the Universe, how was it created, how old is it, what are the stars, what powers the stars, how far away are galaxies, etc, etc) have been answered. We should not downplay that remarkable achievement. We know the age of the Universe to high precision, despite the fact that that age is fully 6 orders of magnitude greater than all of human history. Nevertheless, there is still much we don't know, and likely what we don't know easily exceeds what we do know, by a fair margin. We do not know the nature of the majority of dark matter, we do not know the nature of "dark energy", we do not fully understand why the Universe is filled with matter rather than just energy, etc.
- weichi 17y ago
  waterlesscloud is not saying that there is lots we still don't understand. He is saying that much, perhaps most of what we currently believe is "deeply wrong". This is of course possible, but I think it is very unlikely.

by weichi 17y ago

waterlesscloud 17y ago

The very faq you link to uses cautious language. Look at "currently most accepted model" right there in the first question. If you've followed cosmological history at all, it's been a cascading series of big changes decade after decade. I'm virtually certain the model of 2030 will vary in deep, significant ways from the model of 2010.

weichi 17y ago
Can you be more specific? What parts of the "hot big bang, cold dark matter, accelerating expansion, geometrically flat, ~14 billion years old" model will be shown to be "deeply wrong"? Do you think that discovering, say, the nature of dark energy, is going to demonstrate that the universe isn't really expanding? That we are going to discover that the universe is really 100 billion years old? That the universe was actually colder and larger in the past?

InclinedPlane 17y ago

You're both correct. We know a lot about cosmology compared to what we knew, say, 100 or especially 200 years ago. Many of the big, open cosmological questions throughout human history (what is the Universe, how was it created, how old is it, what are the stars, what powers the stars, how far away are galaxies, etc, etc) have been answered. We should not downplay that remarkable achievement. We know the age of the Universe to high precision, despite the fact that that age is fully 6 orders of magnitude greater than all of human history. Nevertheless, there is still much we don't know, and likely what we don't know easily exceeds what we do know, by a fair margin. We do not know the nature of the majority of dark matter, we do not know the nature of "dark energy", we do not fully understand why the Universe is filled with matter rather than just energy, etc.

weichi 17y ago
waterlesscloud is not saying that there is lots we still don't understand. He is saying that much, perhaps most of what we currently believe is "deeply wrong". This is of course possible, but I think it is very unlikely.