Physics
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Does my space-plunger sound profound? It isn’t. That space absorbs energy is confusing talk. You could desperately try to make it work: Firstly, the “space-plunger” is not moving slowly and the energy lost is partially recovered in the kinetic energy of the expanding space. There is also energy in the gravitational potential, but it is negative, so it cancels the energy being created when a universe comes into existence. Adding all up, the total energy of the universe may be zero, if you fudge it until you get zero. Sounds profound? It isn't.…
A very important new theoretical study appeared yesterday in the hep-ph preprint arxiv. Titled "Precise Predictions on W+4 Jet Production at the Large Hadron Collider", it is signed by a strong team of theorists: C. Berger, Z. Bern, L. Dixon, F. Febres Cordero, D. Forde, T. Gleisberg, H. Ita, D. Kosover, and D. Maitre. I will try to summarize its importance for the physics of the Large Hadron Collider in accessible terms tomorrow; for the time being I just wish to point it out for those who are capable of reading the paper but are too lazy to check the arxiv daily. I know, you belong to this…
What happens to the laws of physics if a fundamental constant turns out to be not a constant after all? The 'magic number' known as the fine-structure constant, called 'alpha' by physicists, appears to vary throughout the universe, according to a team of astrophysicists.
That means the laws of physics would vary throughout the universe also.
The arXiv preprint describes how they determined that the fine-structure constant 'alpha' varies by measuring light from a quasar as it red-shifted due to universal expansion.
Their conclusions are based on measurements taken with the Very…
To physicists, nothing is really a coincidence. Even cats in quantum boxes can be explained in mathematical terms, not to mention roulette or the success or failure of an attack in Dungeons&Dragons, but researchers at the Max Planck Institute for the Physics of Light in Erlangen say they have constructed a device that is truly random and generates random numbers that cannot be predicted in advance.
The researchers exploit the fact that measurements based on quantum physics can only produce a special result with a certain degree of probability, that is, randomly. True random numbers…
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Sean Carroll writes that in GR “spacetime can give energy to matter, or absorb it from matter, so that the total energy simply isn’t conserved”.
He hopefully means “space” not “space-time”, because space-time includes time and has no further time to do anything, let alone absorb stuff. Let us nevertheless do a sympathetic reading and firstly show what he may mean with a simple example:
Imagine electromagnetic radiation (light) inside a box of volume V = L3. Now remove one of the walls and let the radiation spread out into a larger volume, say V’ = 8V. The energy U of the radiation is…
No, it is not a typo. I do mean "quirks": these are hidden-valley brothers of quarks predicted to exist in some fancy new physics scenarios. These particles have been sought by the DZERO experiment in a large dataset of proton-antiproton collisions, making use of a neat technique which I thought could be interesting to briefly explain today.
First of all, let me tell you that quirks so far have only been found in the dream of a few theorists. There is no necessity for their existence, although they could indeed be part of our world and have happily lived undetected this far. Searching for the…
Bantam Books must be happy. Prior to going on sale, Stephen Hawking's* new book 'The Grand Design' has attracted considerable media attention. (See for instance: CNN, BBC, Yahoo, Telegraph, and LA Times.)
What's this fuzz all about?
It all boils down to a media frenzy around a quotation declaring God unnecessary for starting up the universe:
"Because there is a law such as gravity, the universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist [..] It is not necessary to…
Bantam Books moet gelukkig zijn. Voorafgaand aan de hand te koop , heeft Stephen Hawking * nieuwe boek De Grand Design / i > trokken veel aandacht in de media :
http://news.yahoo.com/s/nm/20100902/lf_nm_life/us_britain_hawking
http://edition.cnn.com/2010/WORLD/europe/09/02/hawking.god.universe/inde... # fbid = kZ19DDVscJ_ & wom = false
http://www.bbc.co.uk/news/uk-11161493
http://www.telegraph.co.uk/news/newstopics/religion/7979211/Has-Stephen-...
http://www.latimes.com/entertainment/news/la-ca-stephen-hawking-20100905 , 0,2573263 . verhaal
http://www.guardian.co.uk/science/2010/sep/…
I like to guide your attention to the work of Denis Sciama who in his article "On the origin of inertia" (see reference below) has put a very interesting view not only on the origin of inertia, but also on the origin of gravity. His approach is only very very indirectly related with entropy. However, his approach includes the influence of the whole of the universe.
He starts by simplifying the problem to its bones. He assumes, quite properly, that the most distant items in universe together constitute the largest influence on the chosen subject. The increase of the number of contributing…
A Labor Day special: I am offering you to have a short virtual tour of the CDF Control Room today, free of charge. I am currently on shift there, and we are taking data. If you send me an email with your skype account coordinates, I will call you and show you the place with a web-cam. No audio though, since I cannot disturb my colleagues here. I will complement the visual roundabout tour of the monitors with a few short text explanations. The service is subject to abrupt interruptions or delays due to possible emergencies I need to take care of.
My email is firstname.lastname (at) google.com…