I tweeted this yesterday, but it deserves a blog entry: Gravitational waves discovery now officially dead : Nature News & Comment. A team of astronomers that last year reported evidence for gravitational waves from the early Universe has now withdrawn the claim. A joint analysis of data recorded by the team's BICEP2 telescope at the South … Continue reading Gravitational waves discovery now officially dead
You can get background on what I'm talking about in this post here and here. Probably the best thing to do is let the experts weigh in on this. https://twitter.com/DavidSpergel/status/513848952513642497 https://twitter.com/seanmcarroll/status/513858867327823873 https://twitter.com/seanmcarroll/status/513869684647530496 https://twitter.com/AstroKatie/status/514040997139865600 It's interesting to note that the empirical evidence from BICEP2 has never been called into question, only the interpretation of that evidence. … Continue reading Cosmic inflation appears to have shifted from settled science back to speculation
The radius of the observable universe is often stated to be 46 billion light years. From a certain point of view, this is true, but I think it's a bit of a misleading statement. Occasionally you also see people say that the observable universe is 13.8 billion light years in radius, which is also true, from … Continue reading The size of the observable universe is complicated.
Think of the Big Bang, and you probably imagine a moment in time when matter, energy and space itself all burst into existence at once. Yet many astrophysicists now believe that the “Big Bang” was actually two distinct events: first the inaugural instant of space and time, and second the generation of most of the … Continue reading The Big Bang’s Identity Crisis – The Nature of Reality
Nature has an article up describing the problems with the BICEP2 results that are now being identified by various scientists. It's actually the second one I've seen them publish on this. The astronomers who this spring announced that they had evidence of primordial gravitational waves jumped the gun because they did not take into proper … Continue reading Growing doubt that gravitational waves were actually detected
I've just finished reading Max Tegmark's latest book, 'Our Mathematical Universe', about his views on multiverses and the ultimate nature of reality. This is the first in a series of posts that I plan to do on it. Tegmark postulates four levels of multiverse. This post is about the first, and simplest version, the Level I … Continue reading Tegmark’s Level I Multiverse: infinite space
A few years ago the "it's senseless to ask what came before the big bang because there was no before" meme was hot. I remember Stephen Hawking saying it in his documentary a year or two ago. There now seems to be a good amount of push-back from the rest of the cosmology community to this certitude. … Continue reading xkcd: Cosmologist on a Tire Swing
Last week, I did a brief post asking if anyone knew why the horizon problem was a problem since the universe had started as an infinitesimally small point. I received a lot of excellent replies, which I'm grateful for. I had a couple of people ask me to post any answer I might eventually find. … Continue reading The cosmological horizon problem answer, I think
So, even though I already linked to two sources about cosmic inflation this week, this is good enough that I'm also going to throw it in. It's fascinating to me that the large scale structure of our universe is ultimately caused by quantum fluctuations in the earliest moments of the big bang. Click through for … Continue reading PHD Comics: Cosmic Inflation Explained
First, Minute Physics takes a shot at explaining what the BICEP2 team actually found and how it relates to gravitational waves. I think I'm going to have to watch this a second time to pick up everything. http://www.youtube.com/watch?v=4IlBNJbCzfk And Ethan Siegel has an in-depth discussion of cosmic inflation at his Starts With A Bang site.