Comments on: Planck First Light

By: Peter H

Peter H — Mon, 28 Sep 2009 08:55:01 +0000

When will WMAP respond to Liu and Li? Planck will need a stick in the sand to move on from.

By: Eric M

Eric M — Sat, 19 Sep 2009 05:04:50 +0000

@15: Cosmic Kurtosis rolls off the tongue better.

By: Kaleberg

Kaleberg — Sat, 19 Sep 2009 01:29:20 +0000

This reminds me of a question I’ve been meaning to ask. I’ve heard that when you fall into a black hole, everything you see above is blue shifted and is much brighter than it was when you started your fall. How bright does the CMB get? Do you need CMB-block? (Obviously, you’ve got bigger problems, but I was kind of wondering and what with the LHC not producing any convenient black holes …)

By: o1

o1 — Fri, 18 Sep 2009 12:17:25 +0000

I think it won’t be consistent with inflation as I expect CMB to be a result of photon-photon scattering and therefore it should depend on our local Galactic neighborhood.

By: Peter Coles

Peter Coles — Fri, 18 Sep 2009 11:53:30 +0000

If there is non-Gaussianity you might have to rename this blog “Cosmic Skewness”…

By: Cartesian

Cartesian — Fri, 18 Sep 2009 09:34:23 +0000

Hello,

It does look like something fractal, see :
http://eternal-cartesian.blogspot.com/2009/09/6.html

Cordially

By: Ethan Siegel

Ethan Siegel — Fri, 18 Sep 2009 06:12:48 +0000

Sean, I think n_s = 1.00 is even more vanilla, but overall I agree with you. I’ve just seen so many 2- and 3-sigma results over the years in many different subfields of physics simply get overturned when statistics improve and/or new data comes in. I think that — with the exception of non-Gaussianity — there’s very little that’s going to surprise us about Planck. But we don’t know until we do the experiment, and that’s why we do it.

By: Mark

Mark — Fri, 18 Sep 2009 04:17:18 +0000

My predictions:

1. The scale of slow-roll inflation is low

2. No promordial gravity waves are observed

3. The CMB is mostly generated by a late decaying modulus field and not the inflaton

By: Brando

Brando — Fri, 18 Sep 2009 00:28:09 +0000

My question is: will Alan Guth be happy with the data?

By: MedallionOfFerret

MedallionOfFerret — Thu, 17 Sep 2009 22:37:21 +0000

Hey, I can answer the last question. There is a preferred direction to space: down. I know that may seem a little quarky, but that’s exactly what the data will show. Is that cool enough?

By: JoAnne

JoAnne — Thu, 17 Sep 2009 22:10:21 +0000

I’m rooting for a preferred direction in space. That would be cool!

By: Eugene

Eugene — Thu, 17 Sep 2009 21:58:29 +0000

My predictions for Sean’s series of questions :

Yes. Yes. Yes. No, No. No.

By: Jason Dick

Jason Dick — Thu, 17 Sep 2009 21:54:58 +0000

What I’m interested in seeing is whether or not the “axis of evil” reappears in Planck data, as people Eriksen pointed out a while back it is possible that correlated noise might cause such an effect, but if so, then Planck with its very different noise properties should show either a very different “axis of evil”, or perhaps not at all.

By: Sean

Sean — Thu, 17 Sep 2009 21:09:07 +0000

Ethan, those are presumably the most vanilla guesses possible, and therefore likely to be right. If there is good evidence that the perturbations aren’t scale free at high statistical significance, that would certainly be very interesting. And there are various studies indicating that there is a preferred direction in the WMAP data, so if Planck says that it’s not there, that’s interesting in its own right.

By: Sili

Sili — Thu, 17 Sep 2009 20:53:45 +0000

August, eh? Good timing – it’ll be nice to know the answer to the origin of it all before the end of the world.

(wink goes here)

By: Rory Kent

Rory Kent — Thu, 17 Sep 2009 20:50:13 +0000

On that note, does the Planck use the same statistical method as the WMAP (Spherical Mexican Hat Wavelets)?
If not, could it be used to confirm/deny the “statistcal error” explanation of the cold spot?

By: Ethan Siegel

Ethan Siegel — Thu, 17 Sep 2009 20:49:39 +0000

Sean, I’m going to hazard an educated guess at your questions, in order:

Yes, the CMB is consistent with inflation.

Yes, there are non-Gaussian features in some regions, but the non-Gaussianity is going to be small and not necessarily compelling.

The strength of the perturbations will be slightly diminished at smaller distances, but nothing surprising (maybe n_s = 0.97).

No, we won’t learn anything from polarization.

And no, there’s no preferred direction, at least not with any statistical significance.

Do you think the answers will be any different from this?

By: Ellipsis

Ellipsis — Thu, 17 Sep 2009 20:35:02 +0000

Yes, perhaps the first thing to ask is how consistent is the data from this slice with the WMAP data from that region of sky?

By: Thanny

Thanny — Thu, 17 Sep 2009 20:14:17 +0000

It will be interesting comparing the full image, when it’s complete, with COBE and WMAP, to see, visually, how much more detail there is.