>No dark energy >No accelerated expansion https://www.

>>8514268
>What is your thoughts on this recent PBS Space Time video?

I think astronomers should do their thinking for themselves, instead of trying to get /sci/ to do it for free.

Fuckers are getting paid, after all.

What I get from it is that apparently there may be less dark energy than previously thought.

I mean, constant expansion still requires a cosmological constant, i.e. dark energy

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I've read the actual paper and it's total crap. They're abusing the press release system. All they do in this papers is reanalyse a single cosmological data set (Supernova Union 2.1) using different methods than everyone else and find no acceleration is only rejected at ~2.8 sigma. (Convientently it doesn't reject their pet model and no it was not blinded). They have made a big fucking deal about this but it's nothing. Take a look at their main plot, no acceleration is the green line, the data favors acceleration. The major issue is that there are dozens of cosmological datasets such as Planck Cosmic Microwave Background Constraints, Baryon Acoustic Oscillation data, local Cepheids, redshfit space distortions... They have ignored all of these when in real cosmology we combine these different datasets to find out what the joint constraint is. So even accepting their work dark energy is still very necessary in cosmology, you don't get to ignore the vast majority of data and then make big claims. Even their bullshit logic for rejecting this data doesn't hold because they admit in the press release that there is another test (the ISW effect) which meets their "dynamical" definition (also bullshit) but they ignored that data too.

They try to make a big deal that in this wider dataset the significance hasn't improved over smaller ones but that is utter bullshit, they haven't used their method on the smaller datasets.

>>8514601
>constant expansion still requires a cosmological constant
no it doesn't, in General relativity any universe with some energy constant (such as in the form of matter), will expand since the rate of expansion is proportional to the total energy content of space. You only need the cosmological constant when this expansion accelerates, in other words when you need the energy of the universe to increase with time, since the cosmological constant contributes a total energy proportional to the volume of space, thus if space expands the energy content of the universe also increases, thus expansion rate increases.

Weve known that the universe is expanding since 1930 yet it was only in the 1990s that we re-added the cosmological constant when we realized it is accelerating.

>>8515212
>with some energy constant
*energy content

>>8514268
thats not what it says,just watch it

He looks like Todd Trimble!

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>>8515212
>Weve known that the universe is expanding since 1930 yet it was only in the 1990s that we re-added the cosmological constant when we realized it is accelerating.
Prior to the discovery of acceleration it was assumed that the expansion of the universe was decelerating. Hence how the term "deceleration parameter" arose from. Any expansion universe that is matter dominated cannot continue to expand at the same rate forever. Even now under standard cosmology the universe spent half it's age decelerating before the cosmological constant came to dominate over the decreasing matter density.

>will expand since the rate of expansion is proportional to the total energy content of space.
No, the change in the rate of acceleration is proportional to the energy density but that's beside the point. The point is as the universe expands the energy density of space changes. A matter only universe cannot have constant expansion. See this equation derived from the Friedmann equations for a flat universe, and you can assume a cosmological constant (w=-1). You'll note you cannot set Omega_de=0 and have a constant expansion. You'll see it's also traced on a plot from the paper we're discussing showing you need dark energy:
>>8514602

>>8515682
Silly me. Obviously if you have a matter dominated universe with Omega_m =/= 1 then that equation doesn't apply but you can add in a curvature term of [eqn]\Omega_k (1+z)^2[\eqn]. You get the point anyway. Also a non-flat universe isn't consistent with the CMB so you really can't just dump dark energy.

>>8514268
>>No dark energy
>>No accelerated expansion
Did you even watch the video?

>>8514584
>I think astronomers should do their thinking for themselves, instead of trying to get /sci/ to do it for free.

Do you actually think that there are astronomers who are being paid to go to /sci/ to ask their scientific questions? Did they find something special about this board that I haven't? Maybe there's a high perecentage of savants here who's potentials haven't been tapped yet, and they refuse to work.

>>8514268
its almost like we don't really know whats going on.

>>8516013
Well with the systems in place today it's not very easy for an original idea to move up without money, no matter how good.