EDGES antenna, by Suzyj, Wikicommons

This month’s podcast features the exciting discovery of signs of the first stars made by astronomers using the EDGES experiment, in Western Australia (right), published in Nature, in February. It’s long been predicted that they should see such an indirect signal, which they picked up as a dip in the intensity of radiation in the cosmic microwave background (the afterglow of the big bang). But while this signal was where they thought it would be, and confirmed when they thought the first stars appeared — some 180 million years after the big bang — the detection raised new puzzles. The signal was far stronger than had been predicted. So, I spoke with cosmologist Rennan Barkana, of Tel Aviv University in Israel, who published a companion paper in the same edition of Nature, offering a possible solution: the boosted signal could be caused by an unexpected interaction with dark matter, in the early universe.



Next, reporter Sophie Hebden chatted to cosmologist Eugene Lim, of King’s College London, about what we may be able to infer about observers in parallel universes. Lim, and his colleague Richard Easther, at the University of Auckland, are examining the possibility that we live in a multiverse of neighbouring cosmoses that each have different physical laws. But how likely is it that sentient observers will arise in those regions? What are the minimal set of physical properties needed for such observers to evolve? And what might our multiversal neighbours be able to measure? Answering such questions might help explain why our universe has the peculiar rules that it does. (You can read more about Lim and Easther’s work in Sophie's article, "Our Place in the Multiverse.")

And, if you're wondering what we do when we're not podcasting, the answer, for Brendan Foster at least, is he enjoys relaxing in Maui. But on this holiday, he took some time to meet with theoretical physicist Garrett Lisi, who has opened a hostel for scientists to visit and spend time working. Listen now to hear Brendan’s verdict on whether staying in such an idyllic location can be productive for research.

Finally, we've been away for a while. In the meantime, we saw the sad passing of two giants of theoretical physics, Joe Polchinski and Stephen Hawking. The latter died after we recorded the main edition, but we've added a few words to commemorate these huge losses. Both shall be missed.

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Hi Zeeya,

I say me if they exist these multiverses with different laws that after all we return still at this uniquness and an universal main sphere and Inside we have all these universe, sphères with their cosmological and quantum sphères but with different laws, it becomes intriguing all this ...

Best Regards

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This is a great experiment and result and so hopefully will spur on further investigations on the spectra of the early universe. The new Webb telescope will of course greatly contribute greatly to our knowledge of the young universe in a much more significant way.

Eventually, the gravity wave sensors of future missions will ultimately reveal the true nature of the early universe and allow us to finally know what has so far been hidden from science.

This measurement of when stars first appear is really important for creation. Without creation, nothing would exist and so the cmb creation is from where we all come. Getting the first stars right will help with the details but the cmb creation is still the bee's knees...

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I am ever so glad that the alert astronomers have actually detected (finite) signs of light from the first stars in the universe. Of course, it would have been better had they spotted actual light from the first stars, but the fact that they were able to isolate the first (finite) stars (without confusing them with the second set of (finite) stars) is yet another sparkling example of scientific capability at its most profound.

Joe Fisher

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These astute Australian astronomers claim to know that although the stars we see with our naked eyes emit light and radio waves, their radio telescope has detected a different kind of radio wave emanating from some sort of very cold gas which existed before it started forming into the first finite stars. But if the extremely cold gas formed the finite first stars, how on earth is it still emitting the special radio wave solely to the Australian radio telescope? Why could not the ultra freezing area be about to form into a spanking brand new set of stars?

Joe Fisher, Realist

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