Is ΛCDM considered "speculative?"

[Schneibster]

I think she's gone a long way farther than I have.

 

Note that if the string landscape is real, then all the other universes will forever remain beyond our horizon. The only clues will be from the CMBR.

 

Technically, the CMBR is a hologram of the universe outside our horizon.

Edited February 22, 2014 by Schneibster

[MigL]

I have read Linde and he considered a multitude of universes inflating continuously, not all starting at the same time. In effect he considered the possibility of a universe starting at the Planck scale, and inflating at any point in space-time, such as your pocket.

He may have modified his ideas since then, but 'echoes' of other inflations alongside our inflation or 'echoes' of a big crunch or bounce prior to the big bang are new to me.

 

Incidentally, since a bounce would have to reset the entropic 'value' of the universe, how would any kind of information ( echo ) be passed from the previous to the present universe.

[Schneibster]

Sure; Eternal Inflation. I thought that was understood.

 

Obviously there haven't been any popping around here recently.

 

I don't see why it would have to affect the entropy of the universe any more than necessary to make a signature in the CMBR. And that's not much entropy any more. The universe went matter-dominant when it became transparent.

 

It's worth mentioning that Susskind is a close personal friend of Andre Linde and has worked with him extensively over many years. His acknowledgement in The Cosmic Landscape mentions Linde very warmly, and not just in a list of other names. It's clear his thinking on cosmology has been strongly influenced by Linde; and also Alex Vilentkin and Alan Guth, both of whom he also knows personally and has worked with. I am pretty sure he had Linde and Vilentkin look the book over while he was writing it from the way he talks.

Planck is awesome. You can really see the four low-n harmonics in the picture: http://sci.esa.int/science-e-media/img/61/Planck_CMB_Mollweide_625.jpg as well as the "cold spot" just to the right of and below center. I wonder what other interesting things the image is hiding if we could get a better projection. Or even just move the "midpoint" around to explore the image more thoroughly. I trust the human brain beyond any mathematical formula or machine for pattern recognition. We're so good we have a major problem with false positives. But if there's a pattern there, then there is a human mind that will spot it. That's the advantage of there being six billion of us.

 

In fact, the whole Planck site is pretty good; this ESA press release has some of their best graphics, as well as a great overview: http://sci.esa.int/planck/51551-simple-but-challenging-the-universe-according-to-planck/

 

Enjoy.

Edited February 22, 2014 by Schneibster

[Coyote]

What would be more appropiate to say:

 

The cosmological constant is a type of dark energy

 

or

 

Dark energy is a type of cosmological constant.

 

?

 

I think is the first, but i'm just an aficionado.

Edited March 1, 2014 by Coyote

[ajb]

A cosmological constant will have the same value everywhere, but we have models of dark energy based on scalar fields that do not have this property.