Of Particular Significance

Tag: astronomy

Possible Important Discovery at IceCube

IceCube [here’s my own description of the experiment], the big high-energy neutrino experiment cleverly embedded into the ice at the South Pole, announced a very interesting result yesterday, following on an already interesting result from a few weeks ago, one that I failed to cover properly. They have seen the highest-energy neutrinos ever observed, ones that, unlike previously observed high-energy neutrinos, appear not to be generated by cosmic rays hitting the top of the atmosphere. Instead, they apparently come from new sources far out in space. And as such, it tentatively appears that they’ve opened up, as long anticipated, a new era in neutrino astronomy, in which high-energy neutrinos will be used to understand astrophysical phenomena!

[The only previous example of neutrinos being used in astrophysics occurred with the discovery of neutrinos from the relatively nearby supernova, visible with the naked eye, that occurred in 1987. But those neutrinos had energies millions of times smaller than the ones discussed here. And there was hope that IceCube might see neutrinos specifically from gamma-ray bursts, including the one that occurred just two weeks ago; but that appears not to have happened.]

I don’t understand certain details well enough yet to give you a careful explanation — that will probably come next week — but here’s an early description (and expert readers are strongly encouraged to correct any errors.) (more…)

POSTED BY Matt Strassler

ON May 16, 2013

Big Bright Burst

This is hot off the stellar press: as NASA announced today (with cool pictures), a brilliant, long, and rather nearby GRB, or “gamma-ray burster”, was observed on April 27th, initially by the Fermi and Swift satellites. Gamma-rays are just an old name for photons (i.e. particles of light) which have lots more energy (per photon) than the photons of visible light. And a GRB is a distant astronomical explosion that produces an enormously bright flare of these high-energy photons, typically for a short time (seconds or minutes), though this one lasted for hours. It is believed that a narrow jet of high-energy particles produced in a supernova (a powerful explosion of a star) is behind these flares, but they are still poorly understood and are under active study.

Everything about last week’s GRB is on the exceptional side. The most energetic photon detected had somewhat more energy than the photons produced in the decays of Higgs particles, a bit less than the energy of the photons that Fermi might be seeing from dark matter, and more than three times more energy than any GRB photon previously detected by Fermi. Its gamma rays were produced for many hours, setting another record. It lasted so long that several other types of telescopes were able to observe it, including those that look at visible light (it was even seen by an amateur astronomer), and those that look at radio waves (which are made from photons with vastly lower energy). And it was relatively close… well, relatively compared to most GRB’s. It occured in a galaxy 3.6 billion light years away. Now that is still a good fraction of the distance across the visible part of our universe, but still, it puts this GRB in the top 5% as far as proximity to Earth.

With such a vast amount of data to work with, it seems very likely that astronomers will learn qualitatively new things about GRBs by studying this blast. In astronomy, it sometimes takes just one spectacular event to change the scientific landscape! The next phase of the process will involve directly detecting the lesser (but still intense) glow from the (presumed) supernova that produced the GRB flare. Stay tuned! It should be a matter of a week or so…

POSTED BY Matt Strassler

ON May 7, 2013

A Murky Matter, Several Times Over

Dark Matter, Dark Matter, Everywhere! It’s in your shoes, it’s in your coffee, it’s in the stars and even in your favorite cheese… at least, it’s widely believed to be wandering all about, mostly unnoticed. Still it’s not quite as inscrutable as its reputation would lead you to believe. It’s responsible for a galactic glow, an abundance of anti-matter, and now — three quiet little taps in an underground mine.

Or is it?

Apparent effects of dark matter have been “discovered” so many times in the last decade that you may by now feel a bit jaded, or at least dispassionate. Certainly I do. Some day, some year, one of these many hints may turn out to be the real thing. But of the current hints? We’ve got at least six, and they can’t all be real, because they’re not consistent with one other. It’s certain that several of them are false alarms; and once you open that door a crack, you have to consider flinging it wide open, asking: why can’t “several” be “all six”? All of the dark-matter search experiments are difficult, as they involve pushing the technological envelope. And as anyone with experience in science knows, most of the exciting-sounding results emerging from forefront experiments don’t survive the test of time. Never underestimate the challenge of science at the frontier of knowledge!

Still, as of two weeks ago, we have a new dark matter hint to talk about. So here’s a summary of the various hints, including the new one, exploring their implications and their consistency.

POSTED BY Matt Strassler

ON April 29, 2013

Northern Lights Tonight?

[UPDATE, midnight New York time: the cloud of particles from the solar flare arrived a few hours ago, but it didn’t impact the earth’s magnetic field quite as hard as the best-guess forecast. (Remember the probability of a geomagnetic storm was only 60%; i.e. the probability of no storm was 40%.) Right now, the auroras are likely visible in Canada but probably not in the US. This could change, but don’t get your hopes up too high; we may have to wait for the next solar flare.]

I’ve been sidelined with computer troubles and non-science activities, so first, a belated thanks to everyone who left a thoughtful comment after Monday’s post and question about communicating science to the public. I appreciate hearing your views, especially from readers with a diversity of backgrounds!

Now, many of you may have heard that there is a forecast of northern (and southern) lights, also known as auroras, tonight. What you’ve heard is correct: today’s NOAA space-weather forecast, from http://www.swpc.noaa.gov/forecast.html, says

VI.  Geomagnetic Activity Probabilities 13 Apr-15 Apr
A.  Middle Latitudes
Active                30/30/15
Minor Storm           35/45/05
Major-severe storm    10/15/01
B.  High Latitudes
Active                10/15/15
Minor Storm           20/25/20
Major-severe storm    60/35/20

i.e. it shows that even in mid-latitudes (meaning northern US and southern Canada, and northern Europe, along perhaps with parts of Australia and New Zealand [?]) they are estimating a 35%-45% probability of a minor `geomagnetic storm’ tonight, with a 10-15% probability of a major storm… and a geomagnetic storm, which literally means a lot of activity in the earth’s magnetic field, generally leads to auroras further away from the north and south pole than usual. (more…)

POSTED BY Matt Strassler

ON April 13, 2013

AMS Presents Some First Results on Cosmic Rays and Dark Matter

The Alpha Magnetic Spectrometer [AMS] finally reported its first scientific results today. AMS, a rather large particle physics detector attached to the International Space Station, is designed to study the very high-energy particles found flying around in outer space. These “cosmic rays” (as they are called, for historical reasons) have been under continuous study since their discovery a century ago, but they are still rather mysterious, and we continue to learn new things about them. They are known to be of various different types — commonly found objects such as photons, electrons, neutrinos, protons, and atomic nuclei, and less common ones like positrons (antiparticles of electrons) and anti-protons. They are known to be produced by a variety of different processes. It is quite possible that some of these high-energy particles come from physical or astronomical processes, perhaps very exciting ones, that we have yet to discover. And AMS is one of a number of experiments designed to help us seek signs of these new phenomena.

The plan to build AMS was hatched in 1995, and the detector was finally launched, after various delays, in 2011, on a specially-ordered Space Shuttle mission. Today, Sam Ting, winner of the Nobel Prize for a co-discovery of the charm quark back in 1974, presented AMS’s first results — a first opportunity to justify all the time, effort and money that went into this project. And? The results look very nice, indicating the AMS experiment is working very well. Yet the conclusions from the results so far are not very dramatic, and, in my opinion, have been significantly over-sold in the press. Despite what you may read, we are no closer to finding dark matter than we were last week. Any claims to the contrary are due to scientists spinning their results (and to reporters who are being spun).
(more…)

POSTED BY Matt Strassler

ON April 3, 2013

Cosmic Conflation: The Higgs, The Inflaton, and Spin

Over the past week or so, there has been unnecessary confusion created about whether or not there’s some relationship between (a) the Higgs particle, recently discovered at the Large Hadron Collider, and (b) the Big Bang, perhaps specifically having to do with the period of “Cosmic Inflation” which is believed by many scientists to explain why the universe is so uniform, relatively speaking. This blurring of the lines between logically separate subjects — let’s call it “Cosmic Conflation” — makes it harder for the public to understand the science, and I don’t think it serves society well.

For the current round of confusion, we may thank professor Michio Kaku, and before him professor Leon Lederman (who may or may not have invented the term “God Particle” but blames it on his publisher), helpfully carried into the wider world by various reporters, as Sean Carroll observed here.

[Aside: in this post I’ll be writing about the Higgs field and the Higgs particle. To learn about the relationship between the field and the particle, you can click here, here, here, or here (listed from shortest to most detailed).]

Let’s start with the bottom line. At the present time, there is no established connection, direct or indirect, between (a) the Higgs field and its particle, on the one hand, and (b) cosmic inflation and the Big Bang on the other hand. Period. Any such connection is highly speculative — not crazy to think about, but without current support from data. Yes, the Higgs field, responsible for the mass of many elementary particles, and without which you and I wouldn’t be here, is a spin-zero field (which means the Higgs particle has zero spin). And yes, the “inflaton field” (the name given to the hypothetical field that, by giving the universe a lot of extra “dark energy” in the early universe, is supposed to have caused the universe to expand at a spectacular rate) is also probably a spin-zero field (in which case the inflaton particle also has zero spin). Well, fish and whales both have tails, and both swim in the sea; yet that doesn’t make them closely related. (more…)

POSTED BY Matt Strassler

ON March 26, 2013

The Universe According to Planck (The Satellite)

The big news overnight for science was the best measurement yet of the Cosmic Microwave Background [CMB], by the Planck Satellite. The CMB consists of microwave photons (particles of light with microwave wavelengths) that are the tell-tale leftover glow from the universe’s hot period, the Big Bang. These photons are almost entirely uniform across the sky, and consistent with a glowing object of temperature 2.7 degrees ~~Kelvin (or Centigrade)~~ [poorly written] above absolute zero, the temperature where everything moves as slowly as allowed by quantum mechanics. (Note added: A change of 1 degree Kelvin is the same as a change of 1 degree Centigrade, but absolute zero is 0° Kelvin and -273.15° Centigrade. Centigrade and Celsius are the same.) But they aren’t quite uniform! And those slight non-uniformities, which speak volumes about the universe, have now been read with the greatest precision ever achieved.

The Cosmic Microwave Background - as seen by Planck and WMAP. Credit: ESA and the Planck Collaboration; NASA / WMAP Science Team — The Cosmic Microwave Background – as seen by Planck and its predecessor, WMAP. Credit: ESA and the Planck Collaboration; NASA / WMAP Science Team

Today my chores prevent my writing a proper post, and it doesn’t help that Planck released over a dozen papers overnight… it will take a while to sift through this. But the bullet points that everyone is talking about are (more…)

POSTED BY Matt Strassler

ON March 21, 2013

Why, Professor Kaku? Why?

Professor Michio Kaku, of City College (part of the City University of New York), is well-known for his work on string theory in the ~~1960s and~~ 1970s, and best known today for his outreach efforts through his books and his appearances on radio and television. His most recent appearance was a couple of days ago, in an interview on CBS television, which made its way into this CBS news article about the importance of the Higgs particle.

Unfortunately, what that CBS news article says about “why the Higgs particle matters” is completely wrong. Why? Because it’s based on what Professor Kaku said about the Higgs particle, and what he said is wrong. Worse, he presumably knew that it was wrong. (If he didn’t, that’s also pretty bad.) It seems that Professor Kaku feels it necessary, in order to engage the imagination of the public, to make spectacular distortions of the physics behind the Higgs field and the Higgs particle, even to the point of suggesting the Higgs particle triggered the Big Bang.

In doing this, Professor Kaku sows confusion among journalists and the public, and undermines the efforts of serious particle physicists to explain and convey, both vividly and accurately, the science and the excitement of our time. And on what grounds does he justify this? Doesn’t the taxpaying public deserve the truth? Isn’t the truth already exciting enough? And what will the public think of science if, in this information era, the promulgation of falsehoods and near-falsehoods on national media is unanswered by complaints from other scientists?

I’m so frustrated with Professor Kaku’s unfortunate remarks that rather than write more today, I’ll simply direct you to Sean Carroll’s blog — Sean’s response was much more measured and polite than mine would be if I spoke my mind. For now I’ll just conclude by suggesting that Professor Kaku has some serious explaining to do — to his scientific colleagues, to the science journalist that he misled, and to the public.

(Perhaps you will ask me the same question: “Why DOES the Higgs particle matter?” Here’s my own article from July giving the answer; it’s short and condensed, but it’s not false, as my colleagues will attest! For a longer explanation with more details and fewer shortcuts, you can try Sean Carroll’s book or Lisa Randall’s book, or you can poke around on my website for various related articles; there’s the Higgs FAQ, the story of the Higgs discovery, an article on why the Higgs is not related to gravity, or if you’re really ambitious you can try this set of articles [which requires you first read this set] which is suitable for people who once took a little first-year college physics.)

POSTED BY Matt Strassler

ON March 19, 2013

A Comet (Etc.) Well Worth Seeing

I’m pleased to say that last night I found comet Pan-STARRS, which is gracing the western sky just after sunset, and so I can recommend now that you all give it a try. Binoculars will definitely make it easier to find, and allow you to see more of it. It looks great! Here are some thoughts on how to find it, appropriate if you’re in a country at roughly the same latitude as the United States. (If you live far to the north or far to the south, you’ll need to get advice from someone who found it in a latitude similar to yours. I don’t believe people in the southern hemisphere can still see it.) (more…)

POSTED BY Matt Strassler

ON March 13, 2013

Wednesday: Sean Carroll & I Interviewed by Alan Boyle

On Wednesday February 6th, at 9 pm Eastern/6 pm Pacific time, Sean Carroll and I will be interviewed by Alan Boyle on “Virtually Speaking Science”. The link where you can listen in (in real time or at your leisure) is http://www.blogtalkradio.com/virtually-speaking-science/2013/02/07/sean-carroll-matt-strassler-alan-boyle

What is “Virtually Speaking Science“? It is an online radio program that presents, according to its website:

Informal conversations hosted by science writers Alan Boyle, Tom Levenson and Jennifer Ouellette, who explore the explore the often-volatile landscape of science, politics and policy, the history and economics of science, science deniers and its relationship to democracy, and the role of women in the sciences.

Sean Carroll is a Caltech physicist, astrophysicist, writer and speaker, one of the founders of the blog Cosmic Variance, who recently completed an excellent popular book (which I highly recommend) on the Higgs particle, entitled “The Particle at the End of the Universe“. Our interviewer Alan Boyle is a noted science writer, author of the book “The Case for Pluto“, winner of many awards, and currently NBC News Digital’s science editor [at the blog “Cosmic Log“].

I was interviewed on Virtually Speaking Science once before, by Tom Levenson, about the Large Hadron Collider (here’s the link). Also, my public talk “The Quest for the Higgs Particle” is posted in their website (here’s the link to the audio and to the slides).

POSTED BY Matt Strassler

ON February 4, 2013

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Tag: astronomy

POSTED BY Matt Strassler

POSTED BY Matt Strassler

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