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Archive for April, 2013

This article originally appeared in Fermilab Today on April 26, 2013.

Images from the Dark Energy Camera before (left) and after (right) a supernova explosion in a galaxy about 2 billion light-years away.

Images from the Dark Energy Camera before (left) and after (right) a supernova explosion in a galaxy about 2 billion light-years away.

The Dark Energy Survey (DES) collaboration has captured images of 176 star explosions, called supernovae, including 16 that occurred farther than 7 billion light-years away and when the universe was only about half as old as it is today. A new type of CCD detector contained in the Dark Energy Camera enabled identification of the distant supernovae, making DECam about 10 times more sensitive than other optical cameras to the long-wavelength (red and near-infrared) light coming from these very distant explosions. This improved sensitivity will allow the DES collaboration to find more supernovae from this period in the history of the universe than any other project.

Our current understanding is that the universe is made up of about 70 percent dark energy and that this dark energy is causing the universe to expand at an accelerating rate. Measuring Type 1a supernovae is a way to study dark energy. The fainter the observed explosion, the further away it is, similar to the difference in brightness between nearby and distant candles. As the light of the explosion travels to us, it is stretched by the expansion of the universe and becomes redder. By combining the measured brightness and information about how much the light is stretched, cosmologists can calculate the expansion rate of the universe.

The Dark Energy Survey collaboration includes scientists, postdocs and graduate students from around the world, who worked together to build the camera, collect the images and identify the supernovae described in this result.

The Dark Energy Survey collaboration includes scientists, postdocs and graduate students from around the world, who worked together to build the camera, collect the images and identify the supernovae described in this result.

The amount and wavelength of a supernova’s light determines its age and type. Researchers use filters that divide optical light into four separate parts, with each filter allowing only certain wavelengths to pass through. We know these 16 supernovae are about 7 billion light-years away because most of the light was observed with the filter that allowed only the reddest light to pass through and be measured by the special red-sensitive detectors in the camera. Less sensitive cameras require time-consuming follow-up observations to determine the supernova age.

To search for supernovae, the DES observers take images of the same patch of sky every four to seven days. Then they subtract the images from each other and search for differences. Computers and teams of people looked at thousands of sets of DECam images to find the 176 candidate supernovae. So far five of the candidates have been followed up, and all five were confirmed to be type 1a supernovae.

The Dark Energy Survey will measure more than 3,000 type-1a supernovae in the next five years and provide new information about the mysterious nature of dark energy. For more information, see the Dark Energy Survey website.

Brenna Flaugher

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I wanted to bring to everyone’s attention a really great opportunity that is happening tomorrow. The Intensity Frontier Workshop at Argonne National Labs is taking place this Thursday (4/25/13) and Friday (4/26/13) and Snowmass Young has been given an entire parallel session during this important pre-Snowmass meeting.

We have had three speakers agree to come and speak to the young scientists community about things that matter to people early in their career. They will be speaking during the first parallel session at the meeting from 10:45 am – 12:45 pm (central time).

Our speakers are:

Regina Rameika (FNAL): Speaking about skills young scientists need and some of her experiences from recent hiring committees

Alan Stone (DOE): The funding process and what young people should know about the DOE

Randal Ruchti (NSF): The funding process and what young people should know about the NSF

These titles were intended to be rough prompts, so you should expect these speaker will talk about a broad range of subjects and be available for questions afterwards. This is a really great opportunity to speak with senior scientists and funding agencies directly and ask the questions you’ve always wanted to know. It would be great if these talks could be well attended by all the young snowmass people at the conference and of course is open to all attendees! We have left the rest of the Snowmass Young parallel sessions open as “discussion” and instead just encourage people to be involved at the meeting.

The indico site where the talks will be posted is here:

https://indico.fnal.gov/conferenceTimeTable.py?confId=6248#all.detailed

For those attending the Argonne workshop we will be in building 362 Room E-188. For those remote we will have Ready Talk setup:

Step 1: Dial-In
U.S. & Canada: 866.740.1260
Access Code: 7344724

Additionally we will have a general community meeting to discuss progress made towards the general Snowmass meeting, preliminary results from the survey, and what sort of questions we want to include in the analysis of the survey data. This meeting will be used to also brainstorm ideas for upcoming events this summer leading up to the Snowmass meeting in July

The Community meeting will be on Friday (4/26/13) at 7pm. This coincides with the Conveners Meeting at the intensity frontier workshop and should allow time for all attending to come if they wish. We will use the same ReadyTalk connection information for this meeting as well. For those at Argonne we will be in building 362 room E-188.

A quick update about the survey

As of today we have 579 people who have taken the survey! This is a great start but still shy of our goal of >1500 people. So please take this chance, if you haven’t already, and complete the survey.

A chart showing the rate of responses thus far to the Snowmass Young Survey

http://tinyurl.com/snowmassyoung

If you have taken the survey, please use social media (Facebook, twitter, blogs, etc…) and tell people about it. This survey is open to all who are currently in HEP or have been in HEP at one time. We need “young” and “old” alike to take the survey to have a reasonable representation of the opinions of people in HEP! Likewise we should stress that this is open to U.S. based and non-U.S. based scientists as well. We are trying to get a snapshot of the entire field, and I know it is larger than 579 people.

Additionally, we are really looking for people who were at one time trained in HEP and have since left the field. This section of the survey will be very helpful for side-by-side comparisons with people who are still in the field as well as provide information about what people do once they leave HEP. So if you know anyone who did undergraduate, graduate, post-doctoral, (etc…) training in HEP and is now working “outside the field” please point them to the survey as well.

Thanks to all who have taken time to help Snowmass Young so far and stay tuned for exciting upcoming events leading to the Snowmass Workshop.

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科学者を展示する.

Tuesday, April 23rd, 2013

f:id:D-brane:20130422113439p:image:right

 

2013年4月20日、いよいよその「実験」を世に試す時がやって来た.理研の一般公開.理論物理学研究者そのものを展示する、という試みである.

展示中.「うぉーすげぇ、わけ分からん数式書いて英語でしゃべってる」「ひょえー、なにこれ」「科学者って必殺ワザ持ってるん?」「これカッコいいねぇ」「ぼくも黒板でさんすうするー」「がちガリレオ!?」

なぜこんな試みをしたか、少しその理由と顛末を書いてみよう.

通常、どこの研究所の一般公開へ行っても、科学の成果を分かり易く説明するコーナーがあふれている.子供をとりこにするような工夫があったり、大人を惹き付けるような仕組みがあったり.研究者も広報部も大変な努力を払って、世間の方々に科学の仕組みや効用を理解してもらいまた訴えている.僕はこのやり方に、かねてから少し、感覚的に疑問を持っていた.

その疑問の理由が明確になったのは、去年の一般公開の時である.僕は、延與放射線研究室の展示のお手伝いとして、対称性の破れを磁石で実演するコーナーを担当していた.小学校低学年の子供がやって来て、磁石をぐるぐる回して遊んだ後、握手を求めて来たのだった.そばに居た親が、「科学者と握手できるのよ、ほら、行きなさい」と、シャイな子供をこちらに誘導していた.恥ずかしそうに小さな小さな手を出したその子は、僕と握手をして、そして、目が輝いた.

僕は不思議な気持ちになった.科学のアウトリーチというのは、「科学って面白いでしょ、ほらこんなに役に立っているでしょ、素晴らしいでしょ」ということを説明する場所だと思っていた.しかし、例えば僕の研究の「超ひも理論」の場合、説明を聞いた人の反応は、眉間にしわを寄せ、「なんだか難しいことをやっているのですね」「物理苦手なので」がほとんどである.宇宙や素粒子に興味を持って来た人も、「へー、そうなんですか、分かっていないことばかりなのですね」という感じである.ところが、それが子供の場合、僕が科学者であるということがまず信じられないほどびっくりすることで、それで握手をする、という人間同士のふれあいが出来るということがまさに感動を呼んでいたのだ.僕は、子供と握手をした時に自分も感動を覚え、科学者をやっていて良かったと心から思った.

f:id:D-brane:20130422113440p:image:right

そこでふと気付いたのである.科学者を展示してはどうか、と.科学の成果を知ってもらうだけでなく、本当の科学を創っているまさにその過程を知ってもらうのは、どうか.

理科離れとか科学立国復活とか、世間では色々という.科学と人間をつなぐものは何だろう.自分の人生を振り返ってみると、そこには科学そのものではなく科学者がいた.たいそうなものではない、人並みの経験である.アインシュタインのことをNHKの番組で知って興奮したり、「ホーキング宇宙を語る」で車いすのホーキングが凄いことをやっているらしいとびっくりしたり、高校の物理や化学の先生がひょうきんでとても楽しい授業だったり、大学に入って宿泊研修の夜に話した物理の先生の話にすごく感銘を受けたり.科学の内容は覚えていない.ただ、どんな人に(テレビであれ実際であれ)出会って、すごくエキサイトしたかと言うのは克明に覚えている.この経験こそが、科学のアウトリーチに欠けているのではないか、と理解したのだ.

f:id:D-brane:20130422113442p:image:right

科学を分かってもらうと同時に、科学者を分かってもらう.人間として科学者が、近所のおっさんと同じように生活をし、ただ科学に没頭して研究成果を出すために人生を賭けている、その事実を展示すべきだ.それが、国民に科学に愛着を持ってもらう近道だ.そう信じるに至った.

目的を実現するための絶好の機会が、理研の一般公開だった.科学に興味を持つ人たちが何千人もやってくるイベント.うちの研究室では、敢えて、科学の説明のための準備は全く行わない、という極端な手法をとった.なぜならこの企画は「実験」だからである.科学には、極限状況を試すことで実際の自然をより深く理解するという手法がある.その教えに従うまでである.

果たして、それは成功だった.もちろん失敗した側面はいくつもある.しかし、科学者が実際に科学を生み出している現場を目にした来乗客の反応は、僕の想像を超えていた.前日までは、まあ30人くらいに見ていただければ最初の試みとしては良いかな、という予想をしていた.ところが、当日は千人ほどの方々に来場してもらい、何時間もそこにとどまって科学者の行動を眺め楽しむ人もいたのである.数々の驚きの声と感想を戴いた.

昨年、自分という理論研究者が研究をしている様子を動画にしてyoutubeに公開してみたのだが、それは最終的にはこの展示のためでもあった.科学は創作活動であり、中身を全部理解できなくても、それを人間として感じることが出来る.芸術と共通の側面を持ち合わせている.youtube動画ではまずそれを、世に問うてみたかったのである.例えば、書道は芸術だが、作品を見るだけでなく、書道家が大きな紙の上で大きな筆を持ち書道の実技をするというパフォーマンスも良くテレビで見るだろう.しかし、科学者がどうやって科学を生み出しているかという様子、特に理論物理の研究者がどうやって科学を創っているのかという様子を公開する、というのは聞いたことが無い.その一方で、朝永振一郎が研究室で楽しそうに物理の議論をしている白黒写真が、科学者としての自分の心に焼き付いている.書道において書道家が実演をするように、科学において科学者が実演をし、それを観客に見てもらうことを、科学者はなぜやらないのだろう.書道家が人間として認知されるからこそ書道が愛されるという側面もあるわけで、科学に愛着を持つ国民を増やし将来の科学者を育てるためには、この側面こそ探求してみる価値が多いにある.

A scientist’s life – condensed

Youtubeは制作者から観客への一方的な流れなので、科学が創られているその一部をテレビ的に流しているだけである.やはり実物が実演しているところを見ていただくのが最も効果的で直接的である.それが、どんなものであれ、またどんな感情をもたらすものであれ、科学が人間の生み出したものであるということを、科学者でない人に最も単純に「感じて」もらうのは、科学を創っている現場を見てもらうことである.こういう理由で、理研の一般公開という最大の機会を利用して、このような展示を開催することにした.

 

f:id:D-brane:20130422113446p:image:medium:left

f:id:D-brane:20130422113445p:image:medium:left

展示内容は単純である.1時間交代で、研究室の若手研究者に、毎日の研究者の議論風景をそのまま(前の日の続きで)黒板で披露してもらう.メインはこれだけである.科学の説明は付けず、議論している研究者の名前と、それぞれの必殺ワザ(カタカナで専門用語.「リサメーション」とか「ホログラフィー」とか「ニュークリアフォース」とか)を表示したパワポをiMacで表示.その横に黄色い理研のジャンバーを着た説明員に立ってもらう(これも研究者の回り持ち).質問をし易いように、説明員から声をかけたりする.

その他の展示は少しだけである.遠くから展示が目につき易いように、研究室入り口のすぐ外に大型テレビで、Youtubeの動画をループで大音量で流しておく.入口には、理論研究者の生態を感覚的に述べたスライドをループで流しておく.入り口そばの机で、僕が座って一日数式の計算をしている.観客は、(動画)→(スライド)→(計算する科学者の展示)→(議論風景の展示) の順に自然と誘導される.

なんと、あるセッションでは、実技の議論をしていた研究者が1時間の議論の後「論文ができました」宣言をした.これはなんとも僕の予想を遥かに超えていた.本当に、観客の目の前で、一つの科学が誕生したのである.

f:id:D-brane:20130422113444p:image:medium:right

来て下さった方のお話は様々だった.「私は会計関係の仕事をしていますが、科学者と同じような感覚もあるのだということを知って驚きました」「大学生の息子が研究者を目指すと言っていたのですが、息子が何をやりたいか分かった気がしました」まさにご自身と科学者を重ね合わせていらっしゃったのである.「式を書いているのに式に数字が無いのはなぜですか」「計算にゴールとノルマはあるのですか」「なぜ外国人がいて英語でしゃべるんですか」科学の内容について、手法について、次々と質問が来る.感動させるコメントがあった:「科学は芸術ですね」

f:id:D-brane:20130422113447p:image

予想以上にたくさんの方に来場いただき、感動してもらって、科学にさらに関心を持ってもらえたという意味で、開催して良かったと思っている.一方、反省点はいくつもある.例えば、科学に興味を持ってもらったその後のフォローアップをやはりやっておかねばならない.今回は極み実験だったのでそれを完全に排したが、やはり、観客に興味を持ってもらったらその後に、もっと知ることが出来る方法なり解説を観客にお伝えするべきだった.twitter/facebook連動や一般公開の他の企画と連動した方が良い.また、この展示だけが理論研究者の全てではなく、世の中にはもっともっと多種多様な理論屋がいて様々なやり方の議論がある、ということも明示するべきだった.もちろん、つまらないと言って通り過ぎる方々もたくさんいたが、それは理解できる.期待していたことと違ってがっかりしたのだろう.僕は、この試みは美術館と同じで、そういう人たちは、一般公開のどこか他の場所、心にしみる作品の前で立ち止まってそれを鑑賞してもらえればそれで良いと思っている.

実演開催中.

「理論の研究者って、こんな風に議論して式を書いて研究してるのねぇ」

この一言が、心にしみた.

 

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A l’occasion de l’ouverture de l’appel à candidature 2013 de “Sciences à l’Ecole” pour l’accueil d’enseignants français au CERN durant une semaine, nous publions ces jours-ci le journal quotidien plein d’humour de Jocelyn Etienne qui a suivi ce programme l’année dernière, au mois de novembre dernier.


Bienvenue en Suisse !
Dimanche 04 novembre 2012

Credit: Jocelyn Etienne

C'est la classe !

Départ de Beaulieu (34) vers 12h30, arrivée au CERN à Genève vers 17h30. Une heure de plus que prévu à cause du voyant d’huile du véhicule qui s’éclaire et qui m’oblige à faire un arrêt supplémentaire pour trouver de l’huile, mais surtout par la faute d’une météo exécrable, une pluie dense qui force à rouler au pas sur l’autoroute. J’évite la taxe autoroutière suisse exorbitante, mais ensuite, le GPS tient absolument à me faire pénétrer dans la CERN par une porte dérobée alors que l’entrée B m’a été chaudement recommandée.

A l’accueil de l’hôtel, on me fournit un laisser-passer et le badge qui permet d’accéder à ma chambre (n°122, première étage, bât. 41), au parking etc… C’est la classe !

Credit: Jocelyn Etienne

L'argent local a la particularité d'être très coloré

Dans le couloir, je croise Nicolas Arnaud de l’IN2P3, principal organisateur du stage. Rendez-vous au restaurant, pile poil à l’heure dite (je dois avoir du sang suisse dans les veines).

En attendant les retardataires, je vais retirer de l’argent local qui a la particularité d’être très coloré (Arthur Honegger et Le Corbusier ne diront pas le contraire). Mon beau billet vert de 50 francs n’est pas sur la photo, je l’ai transformé en frites, veau et endives entre 19 h et 20 h.

Crédit: Jocelyn Etienne

Une salle de conférences qui a sans doute vu passer nombre de brillants chercheurs...

Avant le repas, Mick Storr, autre GO du CERN, nous fait alors visiter le « main building » dans lequel on peut croiser des prix Nobel si on a de la chance.

Dans un couloir, on entend presque les cerveaux qui crépitent (bon, pas trop un dimanche soir quand même, bien que la bibliothèque soit ouverte 24 heures sur 24, 7 jours sur 7 tout l’année), d’autant que c’était derrière l’une de ces portes que le web (attention, le web ! pas internet…) a été conçu.

Enfin, on a l’honneur de s’installer dans une salle de conférences rénovée qui sans doute vu passer nombre de brillants chercheurs faisant résonner les murs de non moins brillants exposés.

Puis retour dans ma chambre où je constate que la propreté et l’ordre suisse ne sont pas des clichés…

A suivre…

Jocelyn Etienne est enseignant au lycée Feuillade de la ville de Lunel.

Pour soumettre sa candidature pour la prochaine session du stage au CERN, c’est par ici.

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La première conférence TEDxCERN, qui aura pour thème « Des dimensions multiples », se déroulera le 3 mai 2013, au Globe de la science et de l’innovation. Il sera possible de suivre une retransmission en direct sur le web depuis l’amphithéâtre principal du CERN et depuis le site de TEDxCERN (avec interprétation simultanée en français). Des instituts partenaires un peu partout dans le monde offriront des retransmissions en direct et des billets sont disponibles pour les personnes de la région de Genève désireuses de participer à partir du CERN.

La manifestation, qui dépassera le cadre de la physique des particules, est organisée avec le soutien de Rolex et servira de tribune à la science dans de nombreuses disciplines, en faisant découvrir des idées nouvelles et audacieuses dans des domaines précurseurs de la recherche et de l’innovation qui pourraient fondamentalement changer le cours des choses.

« TEDxCERN nous ouvrira les portes d’univers multiples où se côtoient diverses disciplines scientifiques faisant apparaitre l’omniprésence de la science dans nos existences », a déclaré Sergio Bertolucci, directeur de la recherche et de l’informatique scientifique au CERN. TEDxCERN, qui a pour objectif d’inciter les jeunes à faire partie de la nouvelle génération de scientifiques, pourra également être suivi sur le web dans tous les instituts qui collaborent avec le CERN à travers le monde. Des invités vedettes, notamment le prix Nobel George Smoot, seront présents.

Quatre courts films d’animation réalisés spécialement pour cette occasion seront  aussi au programme, dont un portant sur l’origine de l’Univers.

TED est un organisme à but non lucratif qui a pour mission de promouvoir « des idées qui méritent d’être diffusées ». Il y a de cela 26 ans, la première conférence TED avait lieu l’espace de quatre jours en Californie. Aujourd’hui, TED soutient les idées novatrices de diverses manières. Lors d’une conférence TED, il est demandé à des personnalités de premier plan, par leurs réflexions ou leurs réalisations, de donner, en 18 minutes au plus, la conférence de leur vie. Ces interventions sont ensuite diffusées gratuitement sur le site TED.com. Par exemple, la physicienne Pat Burchat (ma directrice de thèse) y a donné une superbe présentation sur la nature de la matière sombre.

TEDx est une série de conférences organisées localement de manière autonome, qui permettent à des individus de vivre ensemble une expérience de type TED. Les conférences TEDx associent des interventions vidéos (TEDTalks) et en direct suivies de discussions passionnantes au sein d’un petit groupe. Ces événements portent la marque TEDx, x signifiant « événement TED organisé de façon autonome ». Le programme d’une conférence TEDx doit respecter un cadre général, mais chaque conférence TEDx est organisée de façon autonome, moyennant le respect de certaines règles.

Pionniers ou jeunes scientifiques seront à l’honneur de TEDxCERN : Parmi les ceux et celles qui prendront la parole, Londa Schiebinger, historienne, nous parlera innovations et genre ; Chris Lintott nous expliquera comment découvrir une planète depuis son canapé ; Hiranya Peiris, lauréate du prix 2012 Fowler de la Royal Astronomical Society, s’exprimera sur l’Univers primordial ; Marc Abrahams, maître de cérémonie des Ig Nobel Awards et rédacteur de Annals of Improbable Research, nous dira pourquoi toute recherche – la bonne, et parfois la mauvaise – est improbable ; Eliezer Rabinovici et Zehra Sayers évoqueront SESAME, un projet de recherche au Moyen-Orient réunissant des scientifiques égyptiens, israéliens, jordaniens, palestiniens, turcs, pakistanais et iraniens ; Brittany Wenger, scientifique en herbe de 18 ans et lauréate du prix Google Science Fair 2012, parlera recherche et inspiration ; Becky Parker, lauréate de la première médaille Patrick Moore de la Royal Astronomical Society, nous expliquera pourquoi on n’est jamais trop jeune pour être chercheur ; Gian Giudice, physicien théoricien, nous expliquera ce que les analyses réalisées actuellement sur le Higgs pourraient signifier pour l’avenir de l’Univers : et Alison Lester, physicienne, parlera de la traque de particules avec le détecteur ATLAS.

Le programme complet ainsi que les biographies des orateurs peuvent être consultés sur le site de TEDxCERN.

L’équipe organisatrice espère que ces interventions inspireront, encourageront et célèbreront la pensée scientifique, et, surtout, feront passer le message que la science nous concerne tous.

Pauline Gagnon

Pour être averti-e lors de la parution de nouveaux blogs, suivez-moi sur Twitter: @GagnonPauline ou par e-mail en ajoutant votre nom à cette liste de distribution

(Basé sur le communiqué de presse du CERN)

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CERN to host its first TEDx

Tuesday, April 23rd, 2013

The first TEDxCERN event will take place on 3 May 2013, under the theme ‘Multiplying Dimensions’, at the Globe of Science and Innovation with a Live Webcast at the CERN Main Auditorium and at the TEDxCERN site. Partner institutes all over the world will be hosting live simulcast and tickets are available for people in the Geneva area interested to attend the event at CERN.

Going beyond particle physics, the event, organized with the support of Rolex, will provide a stage for the expression of science in multiple disciplines, unveiling bold, new insights into emerging research and innovations that may fundamentally shape the course of things to come.

“At TEDxCERN, we are opening the door to a multiverse of scientific disciplines, showcasing the many ways that science is present in all our lives,” said Sergio Bertolucci, Director for Research and Scientific Computing at CERN. With the aim of inspiring young people to become a part of the new generation of scientists, TEDxCERN will also be webcast at participating institutes around the globe. The event will have special hosts, including Nobel laureate George Smoot.

Four short animation movies specially made for the occasion will be presented on that day including this on the origin of the Universe.

TED is a nonprofit organization devoted to Ideas Worth Spreading. Started as a four-day conference in California 26 years ago, TED has grown to support those world-changing ideas with multiple initiatives. At TED, the world’s leading thinkers and doers are asked to give the talk of their lives in 18 minutes. Talks are then made available, free, at TED.com. For example, a talk not to be missed is (my thesis adviser) Pat Burchat’s stunning performance on the nature of dark matter and dark energy.

TEDx is a program of local, self-organized events that bring people together to share a TED-like experience. At a TEDx event, TEDTalks video and live speakers combine to spark deep discussion and connection in a small group. These local, self-organized events are branded TEDx, where x = independently organized TED event. The TED Conference provides general guidance for the TEDx program, but individual TEDx events are self-organized. (Subject to certain rules and regulations.)

The speakers for TEDxCERN range from pioneers to young scientists: Londa Schiebinger, historian, on gendered innovation; Chris Lintott, on how to discover a planet from your sofa; Hiranya Peiris, winner of the 2012 Royal Astronomical Society Fowler Prize, on the early universe; Marc Abrahams, MC of the Ig Nobel Awards and editor of the Annals of Improbable Research, on why all good — and some bad — research is improbable; Eliezer Rabinovici and Zehra Sayers on SESAME, a ground breaking research project in the Middle East that is bringing together Israeli, Jordanian, Palestinian, Turkish, Pakistani, and Iranian scientists; Brittany Wenger, 18-year-old scientist and Grand Prize Winner 2012 Google Science Fair, on Research and Inspiration; Becky Parker, winner of the first RAS Patrick Moore Medal, on why you are never too young to be a research scientist; Gian Giudice, theoretical physicist, on what the current Higgs measurement could mean for the future of the Universe and Alison Lester, an ATLAS physicist, will talk about chasing fundamental particles at CERN.

The full program and the biographies of the speakers can be found on TEDxCERN site.

The organizing team hopes to inspire, encourage, and celebrate scientific thinking through these talks, and above all, convey that science matters to everyone.

Pauline Gagnon

To be alerted of new postings, follow me on Twitter: @GagnonPauline or sign-up on this mailing list to receive and e-mail notification.

(Based on CERN press release)

 

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Naturalness

Monday, April 22nd, 2013

This article originally appeared in symmetry on April 16, 2013.

When a scientific result fails the test of “naturalness,” it can point to new physics.

Suppose a team of auditors is tasked with understanding a particular billionaire’s bank account. Each month, millions of dollars flow into and out of the account. If the auditors look at the account on random days, they see varying amounts of money. However, on the last day of every month, the balance is briefly set to exactly zero dollars.

It’s hard to imagine that this zero balance is an accident; it seems as if something is causing the account to follow this pattern. In physics, theorists consider improbable cancellations like this one to be signs of undiscovered principles governing the interactions of particles and forces. This concept is called “naturalness”—the idea that theories should make seeming coincidences feel reasonable.

In the case of the billionaire, the surprising thing is that, on a set schedule, the cash flow reaches perfect equilibrium. But one would expect it to be more erratic. The ups and downs of the stock market should cause monthly variations in the tycoon’s dividends. A successful corporate raid could lead to a windfall. And an occasional splurge on a Lamborghini could cause a bigger withdrawal than usual.

This unnatural fiscal balance simply screams for an explanation. One explanation that would make this ebb and flow of funds make sense would be if this account worked as a charity fund. Each month, on the first day of the month, a specific amount would be deposited. Over the course of the month, a series of checks would be cut for various charities, with the outflow carefully planned to match identically the initial deposit. Under this situation, it would be easy to explain the recurring monthly zero balance. In essence, the “charity account principle” makes what at first seemed to be unnatural now appear to be natural indeed.

In physics, we see a similar phenomenon when we predict the mass of the Higgs boson. While Higgs bosons get their mass in the same way as all other fundamental particles (by interacting with the Higgs field), that mass is also affected by another process—one in which the Higgs boson temporarily fluctuates into a pair of virtual particles, either two bosons or two fermions, and then returns to its normal state. These fluctuations affect the mass of the Higgs boson, and the size of this effect can be calculated using the Standard Model—a theory that predicts, among other things, the behavior of Higgs bosons.

To calculate how much these quantum fluctuations affect the mass, scientists multiply two terms. The first involves the maximum energy for which the Standard Model applies—a huge number. The second is the sum of the effect of the fluctuations to different virtual bosons minus the sum of the effect of the fluctuations to different virtual fermions. If the Higgs mass is small, as recent measurements at the LHC suggest, the product of these two numbers must also be small.  This means the sum effect of the bosons must be almost identical to the sum effect of the fermions, an unlikely scenario that turns out to be true. For this near cancellation to happen “just by accident” is so utterly improbable that it beggars the imagination. A coincidence like this is simply unnatural.

Without some underlying (and currently unknown) physical principle that makes it obvious why this occurs, it is quite strange for the mass of the Higgs to be so low. That is why discovering the Higgs boson is not the end of the story. Theorists have come up with several different explanations for its low mass, and now it is up to the experimentalists to test them.

Don Lincoln

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This article first appeared in Fermilab Today on April 15, 2013.

Scientists around the world are working to understand the nature of dark matter, which accounts for most of the mass of the universe. The earth seems to be moving through a cloud of dark-matter particles that encompasses the visible parts of our galaxy. We should be able to sense this dark matter if we can deploy detectors that are sensitive to the ‘billiard ball’ scatter of a dark matter particle from an atomic nucleus inside these detectors.

Experimental upper limits (90 percent confidence level) for the WIMP-nucleon spin-independent cross section as a function of WIMP mass. The black dotted line is from the present analysis, and the blue solid line includes previous CDMS II silicon-detector data. Also shown are limits from the CDMS II germanium-detector standard and low-threshold analyses (dark and light dashed red), as well as limits from the XENON collaboration (dark and light dash-dotted green). The magenta oval shows a possible WIMP signal region proposed to explain data from CoGeNT. The light and dark blue regions indicate the 68 percent and 90 percent contours obtained if the present result were to be interpreted as a WIMP signal. The asterisk shows the maximum likelihood point under this interpretation.

The Cryogenic Dark Matter Search (CDMS) experiment was designed to do exactly that, using germanium and silicon detectors cooled to very low temperatures in order to detect the electric charge and heat liberated by single dark-matter particle collisions with nuclei and distinguish them from the messier interactions created by normal matter.

At the American Physical Society April meeting in Denver, the CDMS collaboration presented on Saturday its blind-analysis results from data taken with silicon detectors during CDMS II operation at the Soudan Underground Laboratory. Kevin McCarthy, a graduate student from MIT, presented the results, which were submitted to Physical Review Letters.

The blind analysis resulted in three candidate events. Although this number is higher than the expected background of roughly half an event, this is far from a discovery. Simulations of the known backgrounds indicate that a statistical fluctuation could produce three or more events about 5 percent of the time. In other words, if the experiment were done 100 times, five of them would show at least three events in the signal region even if dark-matter particles did not exist.

However, there is more information on the characteristics of the expected background events and the expected signals from weakly interacting massive particles, or WIMPs, which are the favorite particle explanation for dark matter. A likelihood analysis that includes the measured recoil energies of the three events yields a 0.19 percent probability for the background-only hypothesis when tested against a model that includes a WIMP contribution. This translates into roughly a 3-sigma confidence level for the hypothesis that the three events are due to WIMP interactions. This is exciting but still does not meet the scientific standard for a discovery. Further investigations are necessary.

Nevertheless, if one indulges in a “what if” scenario and interprets the result as due to a WIMP signal, the WIMP mass would be around 8.5 times the mass of a proton. For the simplest theories of WIMP interactions and using the Standard Model for dark-matter distribution in our galaxy, the rate found for such interactions is in some conflict with the current results from the XENON experiments. The paper presents more details.

In 2010, the CDMS collaboration published results on dark-matter searches with germanium detectors, which resulted in two events in the signal region and an estimated background of 0.8 events. The conclusion at the time was that these events were likely leakage surface electrons rather than true nuclear recoils, and other experiments have not found any signals in this mass region.

The SuperCDMS Soudan experiment is currently taking data with larger, and better, germanium detectors, and hopes to shed additional light on low-mass WIMPs before the end of the year. The collaboration is considering the use of silicon detectors in future experiments.

—Dan Bauer, Deputy Director, Fermilab Center for Particle Astrophysics

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Early last week Margaret Thatcher, former British Prime Minister, passed away, aged 87. She was a charismatic figure who was known internationally for being a strong and decisive leader. She had close political ties with President Ronald Reagan, she opposed the communist policies in Eastern Europe, and she was skeptical of increasing integration of the UK with Western Europe. Her actions and legacy are entwined with the global political stage at the time. However, in the UK she was very divisive and at times controversial, and even to this day there is a mixture of high praise a bitter resentment about her policies. Much has been said about her legacy over the past few days, and I think that, regardless of one’s own views, one of the best things we can say about Thatcher is that she knew what her vision was, and she pursued it with a great deal of energy and enthusiasm.

Thatcher, the politician (Mirror)

Thatcher, the politician (Mirror)

During her undergraduate years, Thatcher was a chemist at the University of Oxford. It was only later that she studied law and became a politician, so from her very early career she had an appreciation for science. She knew about the care and attention needed to make discoveries, the frustration of waiting for data, and the need for peer review and skepticism. Given her status as an international leader, she had the opportunity to visit CERN in the early 1980s, but as a scientist she took so much more away from the visit than we could have expected.

Thatcher, the chemist (popsci)

Thatcher, the chemist (popsci)

She’d asked to be treated like a fellow scientist, and her questions showed that she had taken her background reading about CERN seriously. She asked why the proposed accelerator, LEP, would be circular and not linear. This is not an easy question to answer unless the person asking has knowledge about how accelerators work. After a discussion with Herwig Schopper, then Director General, she came back to the UK as an ambassador for CERN and LEP was approved in the UK shortly afterwards. One of her questions was very astute. When told that the LEP tunnel would be the last at CERN she knew from experience that scientists will usually want to go further with their research and in particle physics at the energy frontier, further usually means larger. It’s true that CERN has reused the LEP tunnels for the LHC, but there are also proposals for even larger projects that will probe even higher center of mass energies.

Thatcher must have made a very good impression on Schopper during her visit. A recent Scientific American article has revealed that she was told about the discovery of the W and Z bosons before the information was made public. This letter shows that Schopper kept his promise and trusted Thatcher to keep the tantalizing and preliminary evidence to herself:

Schopper writes to Thatcher (Scientific American)

Schopper writes to Thatcher (Scientific American)

When the news of the \(W\) boson discovery was public she wrote to Peter Kalmus of Queen Mary College, London, to offer her congratulations. Naturally she made a point to mention that there was a significant British effort behind the discovery:

Thatcher's letter to Kalmus

Thatcher's letter to Kalmus

On the one hand, Thatcher was genuinely excited about CERN and the research, but on the other she was a fiscally conservative politician with monetarist policies and she had to defend the spending to her colleagues, and to herself. She had to make sure that the physicists at CERN were using the funding effectively, and delivering high quality scientific results for the spending. During a visit to the Super Proton Synchrotron she spoke John Ellis, who introduced himself as a theoretical physicist. The conversation continued:

Thatcher: “What do you do?”
Ellis: “Think of things for the experiments to look for, and hope they find something different.”
Thatcher: “Wouldn’t it be better if they found what you predicted?”
Ellis: “Then we would not learn how to go further!”

Once again Thatcher knew what question to ask, and Ellis knew what answer to give. Thatcher seemed convinced and knew that the people at CERN has the right attitude when it comes to discovery and use of public money. You can see some media coverage of her visit to the UA1 (Underground Area 1) site on the CERN Document Server.

In 1993, three years after Thatcher left office, David Miller from UCL came up with an analogy for the Higgs field where Thatcher played the central role. Essentially we can think of the Higgs field like a room full of people milling around at a cocktail party. Someone famous and popular enters the room, and all of a sudden people crowd around, making this person’s journey through the room harder. They take longer to get up to a good walking speed, and when they are walking they become harder to stop. That’s essentially what mass is- a measure of hard it is to change an object’s velocity. The analogy goes further, to include rumors being spread from the vicinity of this famous person. They would spread in small groups of people, and each group would have its own “mass”, which is what the Higgs boson is, it’s just an excitation of the field in the presence of matter. Who was the famous person in this analogy? Margaret Thatcher, of course!

Thatcher and the Higgs field (Quantum Tangents)

Thatcher and the Higgs field (Quantum Tangents)

So her legacy with CERN is one of a scientist and a politician. She was genuinely excited to see the discoveries take place, she met with the scientists personally and interacted with them as another scientist. She took the time to understand the questions and answers, and even challenged the physicists with more questions. At the same time she put the projects in context. She had to defend the experiments, so she had to challenge the physicists to give her the information she needed to get the support from the UK. In a sense she knew the need for public outreach, to open up CERN’s scientific program to scrutiny from the public so that when we want to push back the frontiers even further we can count on their support.

If we’re to keep pursuing scientific discoveries in the future, we need scientifically literate and inspired politicians. It would be tempting to say that they are becoming more and more rare, but in reality I think things are more favorable than they have been before. With the recent discoveries we’re in a golden age of physics that has made front page news. Multimedia outlets and the internet have helped spread the good word, so science is high in the public consciousness, and justifying further research is becoming easier. However before the modern internet era and the journalistic juggernaut that comes to CERN each time there’s a big announcement it fell on the shoulders of a few people, and Thatcher was one of them.

(I would like to thank John Ellis for providing help with his quote, and for giving the best answer when asked the question!)

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Le premier avril, j’ai annoncé ici que le CERN donnerait dix bosons de Higgs pour remercier le public pour son incroyable intérêt pour la recherche faite au CERN. Environ 1500 personnes se sont inscrites pour ce tirage au sort. Plusieurs ont décrit leur enthousiasme, expliquant combien ils aimeraient en avoir un et ce que cela signifierait pour eux. D’autres n’ont pas été dupes, mais ont voulu jouer le jeu.

C’était vraiment amusant d’avoir la chance de jouer un poisson d’avril qui a fait marcher des gens partout dans le monde. Les inscriptions sont venues de lieux aussi divers que le Pakistan, le Rwanda, la Finlande, le Canada, l’Australie, la Chine et le Portugal. Cela montre l’intérêt incroyable que le boson de Higgs a généré sur tous les continents.

J’ai utilisé un générateur de nombres aléatoires pour sélectionner les gagnant-e-s qui viennent du Mexique, Royaume-Uni, Etats-Unis, Biélorussie (3), Russie (3),  Kazakhstan et Pays-Bas. Une grande partie des entrées venait de Biélorussie et de Russie où un site d’information populaire a reproduit la nouvelle. Les gens ont mordu, même si, comme chacun sait: “Первого апреля никому не верю!” (Le premier avril, ne fais confiance à personne).

Même des étudiant-e-s en physique se sont fait prendre au piège tant leur désir d’avoir leur propre boson de Higgs était fort. Bien sûr, c’était un peu tricher que d’utiliser la renommée du CERN puisque cela donne beaucoup de poids peu importe l’annonce. Mais beaucoup se sont bien amusé-e-s: un homme a essayé de me soudoyer avec un monopôle magnétique. Une femme a promis de le nourrir seulement avec les meilleurs particules. Une autre a dit qu’elle avait déjà beaucoup d’antimatière et saurait comment bien prendre soin d’un boson de Higgs. Un étudiant en physique a indiqué que compte tenu de la courte durée de vie de ce boson, il craignait de se retrouver avec seulement deux bosons W ou Z. Une personne a exprimé combien il était bien que le CERN partage. Certains ont demandé un bosun, bozzon ou bison de Higgs. Un homme m’a dit combien l’obtention d’un boson pourrait l’aider à gagner le coeur de son amie alors qu’il était sur le point de la demander en mariage. Un étudiant très déçu a répondu que les physicien-ne-s étaient cruel-le-s quand il a réalisé que c’était une blague. Il a vite changé d’avis en apprenant qu’il était l’un des dix heureux gagnants.

Des bosons de Higgs spécialement faits pour cette occasion et tout juste échappés du zoo de particules sont en route vers leur nouvelle vie où tous les gagnant-e-s ont dit qu’ils et elles allaient les accueillir chaleureusement.

Pauline Gagnon

Pour être averti-e lors de la parution de nouveaux blogs, suivez-moi sur Twitter: @GagnonPauline ou par e-mail en ajoutant votre nom à cette liste de distribution

 

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