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| This week I was invited at the Center for Fundamental Physics in Maryland, where I gave a talk about black holes and fundamental light fields beyond the Standard Model. On the way back to the airport in Washington DC, I stopped by the Air & Space museum. Here is a picture of me before the Hubble Space Telescope. BTW, in The Mall in DC all museums belong to the Smithsonian Institute and they are free, amazing!) |
Saturday, November 23, 2013
Visit to the Maryland Center for Fundamental Physics
Tuesday, November 12, 2013
[Recommended by us] Why Hot Water Freezes Faster Than Cold—Physicists Solve the Mpemba Effect
Aristotle first noticed that hot water freezes faster than cold, but chemists have always struggled to explain the paradox. Until now.
Water may be one of the most abundant compounds on Earth, but it is also one of more mysterious. For example, like most liquids it becomes denser as it cools. But unlike them, it reaches a state of maximum density at 4°C and then becomes less dense before it freezes.
In solid form, it is less dense still, which is why standard ice floats on water. That’s one reason why life on Earth has flourished— if ice were denser than water, lakes and oceans would freeze from the bottom up, almost certainly preventing the kind of chemistry that makes life possible.
Then there is the strange Mpemba effect, named after a Tanzanian student who discovered that a hot ice cream mix freezes faster than a cold mix in cookery classes in the early 1960s. (In fact, the effect has been noted by many scientists throughout history including Aristotle, Francis Bacon and René Descartes.)
The Mpemba effect is the observation that warm water freezes more quickly than cold water. The effect has been measured on many occasions with many explanations put forward. One idea is that warm containers make better thermal contact with a refrigerator and so conduct heat more efficiently. Hence the faster freezing. Another is that warm water evaporates rapidly and since this is an endothermic process, it cools the water making it freeze more quickly.
None of these explanations are entirely convincing, which is why the true explanation is still up for grabs.
Today Xi Zhang at the Nanyang Technological University in Singapore and a few pals provide one. These guys say that the Mpemba paradox is the result of the unique properties of the different bonds that hold water together.
What’s so odd about the bonds in water? Discover it HERE.
Water may be one of the most abundant compounds on Earth, but it is also one of more mysterious. For example, like most liquids it becomes denser as it cools. But unlike them, it reaches a state of maximum density at 4°C and then becomes less dense before it freezes.
In solid form, it is less dense still, which is why standard ice floats on water. That’s one reason why life on Earth has flourished— if ice were denser than water, lakes and oceans would freeze from the bottom up, almost certainly preventing the kind of chemistry that makes life possible.
Then there is the strange Mpemba effect, named after a Tanzanian student who discovered that a hot ice cream mix freezes faster than a cold mix in cookery classes in the early 1960s. (In fact, the effect has been noted by many scientists throughout history including Aristotle, Francis Bacon and René Descartes.)
The Mpemba effect is the observation that warm water freezes more quickly than cold water. The effect has been measured on many occasions with many explanations put forward. One idea is that warm containers make better thermal contact with a refrigerator and so conduct heat more efficiently. Hence the faster freezing. Another is that warm water evaporates rapidly and since this is an endothermic process, it cools the water making it freeze more quickly.
None of these explanations are entirely convincing, which is why the true explanation is still up for grabs.
Today Xi Zhang at the Nanyang Technological University in Singapore and a few pals provide one. These guys say that the Mpemba paradox is the result of the unique properties of the different bonds that hold water together.
What’s so odd about the bonds in water? Discover it HERE.
Sunday, November 3, 2013
La passione per lo studio delle stelle raccontata dall'astrofisica Marta Burgay
Ecco l'intervento nellla trasmissione di Rai Tre "Che tempo che fa" all'astrofisica Marta Burgay dell'osservatorio astronomico di Cagliari, dove si parla di radiotelescopi, pulsar, pulsar doppie, relatività generale e del lavoro e della passione dei ricercatori in generale :) Buona visione!!
Thursday, October 31, 2013
Recommended by us: "Fermilab special Halloween edition" :)
Fermilab Today special Halloween edition
For the Halloween occurence the popular scientific website "Fermilab Today" decided to put related links and fake news. Take a look here and have fun :)
Wednesday, October 23, 2013
Tuesday, October 22, 2013
Al via, domani 23 ottobre, il Festival della Scienza di Genova
Festival della Scienza Bellezza
Genova, 23 ottobre_3 novembre 2013
Si intitola “Quello che non so” lo spettacolo conferenza dedicato ai grandi misteri della fisica contemporanea ideato dall’Infn per la serata inaugurale del Festival della Scienza di Genova, mercoledì 23 ottobre. Si tratta di un evento unico che propone un format sperimentale pensato per il grande pubblico in cui si alternano talk show scientifico e performance artistiche. Interverranno i protagonisti della scoperta del bosone di Higgs, valsa il Nobel per la Fisica 2013 a Peter Higgs e Francois Englert, Guido Tonelli (spokesperson emerito esperimento Cms) e Fabiola Gianotti – in collegamento dal Cern (spokesperson emerito esperimento Atlas). Accanto a loro Caterina Biscari (ricercatrice Infn e direttore del laboratorio Cells Alba di Barcellona) e Antonio Zoccoli (Giunta esecutiva Infn). Nello spettacolo "Quello che non so" la narrazione scientifica sarà accompagnata dalle suggestioni del mago delle bolle di sapone Marco Zoppi e dai quadri di sabbia animati dalla sand artist Gabriella Compagnone. A condurre la serata sarà Marco Castellazzi (Rai 3 Geoscienza). Lo spettacolo è una nuova versione, aggiornata nei contenuti e nell’impianto artistico, dell’evento "Lo Show dell’Universo" realizzato dall’Infn a Città della Scienza di Napoli nel settembre 2012.
Monday, October 14, 2013
Birth, death, resurgence (and death again) of an idea
One might think that only few great scientists are blessed with those “eureka” moments when, all in a sudden, a great discovery is standing just before their gleaming eyes, so clear and obvious that it cannot be wrong. In my experience, this expectation is very far from reality.
I think that many, if not all, people working on intellectual activities can experience the same feverish excitement that hit Archimedes in its tub. And they actually do so on a regular basis!
The thing is, the relevance of any scientific achievement is very personal and it is proportional to the effort one has put to reach it. No matter whether such achievement would be universally important or not, it will anyway be so for its discoverer. Only great scientists have the privilege to feel such excitement for great discoveries, but most scientists would anyway feel exactly the same emotion after solving much humbler problems, simply because they finally overcome some long-standing intellectual challenge.
There is another big difference between great discoveries and those made by the “scientist of the street”. The former can last forever whereas the latter hardly survive overnight. Furthermore, because Science is sadistic, the more relevant the discovery appeared at the beginning, the shorter the time it will survive. Therefore, although any scientist can feel the birth of her/his own ideas – whatever small its intrinsic impact might be – it is also true that most of us have also to face the frustration of seeing that idea dying as quickly as it was born. I like to believe the same happens to great scientists as well.
Sometimes this process repeats itself continuously, each new idea being accompanied by more mistrustful joy and its possible death being followed by less sorrow. I consider myself lucky in this respect, because I can easily get over-excited after having some new idea (if not in front of a computer, this usually happens on the way back walking from work, so my humble suggestion is to leave your car in the garage) but I don't feel particularly sad when such idea turns out to be completely wrong, as it happens most of the times.
Actually, I think this experience is common to the majority of my colleagues and it is truly fortunate that the excitement following some potential new idea largely overcomes the almost-unavoidable letdown for its failure. After all, I believe, such feeling is the real thrust of the scientific process, the reward any scientist is intimately working for.
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The one above is my own contribution to the outreach project "Birth of Ideas", created by Ana Sousa and Vitor Cardoso. If you have an interesting anecdote to tell, please read the instructions and submit your contribution!
I think that many, if not all, people working on intellectual activities can experience the same feverish excitement that hit Archimedes in its tub. And they actually do so on a regular basis!
The thing is, the relevance of any scientific achievement is very personal and it is proportional to the effort one has put to reach it. No matter whether such achievement would be universally important or not, it will anyway be so for its discoverer. Only great scientists have the privilege to feel such excitement for great discoveries, but most scientists would anyway feel exactly the same emotion after solving much humbler problems, simply because they finally overcome some long-standing intellectual challenge.
There is another big difference between great discoveries and those made by the “scientist of the street”. The former can last forever whereas the latter hardly survive overnight. Furthermore, because Science is sadistic, the more relevant the discovery appeared at the beginning, the shorter the time it will survive. Therefore, although any scientist can feel the birth of her/his own ideas – whatever small its intrinsic impact might be – it is also true that most of us have also to face the frustration of seeing that idea dying as quickly as it was born. I like to believe the same happens to great scientists as well.
Sometimes this process repeats itself continuously, each new idea being accompanied by more mistrustful joy and its possible death being followed by less sorrow. I consider myself lucky in this respect, because I can easily get over-excited after having some new idea (if not in front of a computer, this usually happens on the way back walking from work, so my humble suggestion is to leave your car in the garage) but I don't feel particularly sad when such idea turns out to be completely wrong, as it happens most of the times.
Actually, I think this experience is common to the majority of my colleagues and it is truly fortunate that the excitement following some potential new idea largely overcomes the almost-unavoidable letdown for its failure. After all, I believe, such feeling is the real thrust of the scientific process, the reward any scientist is intimately working for.
---------
The one above is my own contribution to the outreach project "Birth of Ideas", created by Ana Sousa and Vitor Cardoso. If you have an interesting anecdote to tell, please read the instructions and submit your contribution!
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