7.30pm-10pm
Thursday 9th October
Level 8 Common Room, Blackett Lab
7.30pm-10pm
Thursday 9th October
Level 8 Common Room, Blackett Lab
If anyone has any ideas or requests for Physoc events then please get in touch!
physics.society@imperial.ac.uk
]]>If anyone has any ideas or requests for Physoc events then please get in touch!
physics.society@imperial.ac.uk
]]>We are going into schools during this term equipped with physics, fun and food!
If you are intersted in taking part in outreach, please sign up
Updated, check out the outreach lessons
Don't forget, The Big Day of Physics - Saturday the 8th of March!
]]>We are going into schools during this term equipped with physics, fun and food!
If you are intersted in taking part in outreach, please sign up
Updated, check out the outreach lessons
Don't forget, The Big Day of Physics - Saturday the 8th of March!
]]>Synopsis:
A simple laser consists of an optical amplifier placed between a pair of mirrors forming a so-called “optical cavity”. The idea of two mirrors facing each other is perhaps more likely to make you think of hotel bathrooms rather than a topic that might grace the pages of Nature! But physics is full of surprises, and one of them is that the modes of certain optical cavities turn out to be fractals!
Optical cavities are “stable” or “unstable” according to the curvatures and spacing of the mirrors. And the modes of unstable cavities are the ones that exhibit fractal character. The fundamental property of a fractal pattern is that it is unchanged under a change of scale and, since unstable resonators possess an inherent magnification while their modes are self-consistent by definition, the conditions for fractality are fulfilled.
In the talk, the history of the subject will be reviewed, the basic properties of optical resonators will be outlined, and techniques for generating the mode profiles of unstable resonators will be discussed. The important link between the fractal “dimension” (the mathematical measure of fractality) and the resonator geometry will be established. It will be shown that the most obvious visual characteristic of a fractal, its “self-similarity”, is manifested in certain special planes within the resonator.
Examples of fractal mode patterns will be displayed and the related topic of “video” fractals will be mentioned as a light-hearted afterthought. Once more, you might not expect to find a paper in Nature based on pointing a video camera at a screen displaying its own image, but remember that physics is full of surprises, and now here is another one!
Fun and exciting, what more could you want!
]]>Synopsis:
A simple laser consists of an optical amplifier placed between a pair of mirrors forming a so-called “optical cavity”. The idea of two mirrors facing each other is perhaps more likely to make you think of hotel bathrooms rather than a topic that might grace the pages of Nature! But physics is full of surprises, and one of them is that the modes of certain optical cavities turn out to be fractals!
Optical cavities are “stable” or “unstable” according to the curvatures and spacing of the mirrors. And the modes of unstable cavities are the ones that exhibit fractal character. The fundamental property of a fractal pattern is that it is unchanged under a change of scale and, since unstable resonators possess an inherent magnification while their modes are self-consistent by definition, the conditions for fractality are fulfilled.
In the talk, the history of the subject will be reviewed, the basic properties of optical resonators will be outlined, and techniques for generating the mode profiles of unstable resonators will be discussed. The important link between the fractal “dimension” (the mathematical measure of fractality) and the resonator geometry will be established. It will be shown that the most obvious visual characteristic of a fractal, its “self-similarity”, is manifested in certain special planes within the resonator.
Examples of fractal mode patterns will be displayed and the related topic of “video” fractals will be mentioned as a light-hearted afterthought. Once more, you might not expect to find a paper in Nature based on pointing a video camera at a screen displaying its own image, but remember that physics is full of surprises, and now here is another one!
Fun and exciting, what more could you want!
]]>
Synopsis:
The apparently boring yellow globe of the Sun is in reality a highly dynamic and energetic object, which greatly affects our lives and indeed continually sheds plasma which expands to envelop the Earth. Humanity has, over the last 5 decades, launched a large number of spacecraft to study the Sun, both remotely and directly. I will present some of the key facts that we know, present some of the most recent results – including stunning movies from new missions such as STEREO and Hinode – and discuss prospects for the future, which might even include a probe flying through the Sun’s outer atmosphere.
Not one to miss!
]]>
Synopsis:
The apparently boring yellow globe of the Sun is in reality a highly dynamic and energetic object, which greatly affects our lives and indeed continually sheds plasma which expands to envelop the Earth. Humanity has, over the last 5 decades, launched a large number of spacecraft to study the Sun, both remotely and directly. I will present some of the key facts that we know, present some of the most recent results – including stunning movies from new missions such as STEREO and Hinode – and discuss prospects for the future, which might even include a probe flying through the Sun’s outer atmosphere.
Not one to miss!
]]>Synopsis:
One often encounters systems that evolve through periods of relative quiescence separated by brief outbursts of hectic activity. Think of the evolution of ecosystems through extinctions and creations, the motion of tectonic plates through earth quakes or economy and economic crashes. We argue (using models from biology and physics) that the dynamics gradually changes the properties of the involved system in an essential way. E.g. the interactions between species in a young ecosystem are in general weaker than in an old one. We analyse the evolution in terms of the statistics of record times; records being similar to, say, the times at which a new record is achieved in long jump. Complex systems are never static, they are always moving towards the next major abrupt transition.
One not to miss!
]]>Synopsis:
One often encounters systems that evolve through periods of relative quiescence separated by brief outbursts of hectic activity. Think of the evolution of ecosystems through extinctions and creations, the motion of tectonic plates through earth quakes or economy and economic crashes. We argue (using models from biology and physics) that the dynamics gradually changes the properties of the involved system in an essential way. E.g. the interactions between species in a young ecosystem are in general weaker than in an old one. We analyse the evolution in terms of the statistics of record times; records being similar to, say, the times at which a new record is achieved in long jump. Complex systems are never static, they are always moving towards the next major abrupt transition.
One not to miss!
]]>Prof Dmitri Vvedensky - Growth, Geometry, Form, and Fluctuations - November 27th LT3
Fluctuating interfaces are characteristic of many non-equilibrium systems, ranging from snowflakes to quantum dots to malignant tumors. This talk will introduce the basic physics of such systems and discuss their statistical mechanical description. A key element is the use of macroscopic measurements to identify the microscopic processes that are responsible for the form and fluctuations of driven nonequilibrium systems.
Professor Peter Kalmus OBE, Queen Mary, University of London - Antimatter - November 29th LT3
What is antimatter and where might it exist? For every type of particle there is a corresponding antiparticle. The electric and nuclear forces between two antiparticles are the same as between corresponding particles. Thus antiatoms and even antimatter in bulk might exist. However when antiparticles come into contact with ordinary particles they can annihilate each other, so antimatter would not exist for long on Earth unless it was totally isolated. We explain how particle physics could help us to avoid being annihilated by a science-fiction antimatter alien from another world. We review searches for antimatter in the universe, and describe some experiments with antiparticles on Earth.
]]>Prof Dmitri Vvedensky - Growth, Geometry, Form, and Fluctuations - November 27th LT3
Fluctuating interfaces are characteristic of many non-equilibrium systems, ranging from snowflakes to quantum dots to malignant tumors. This talk will introduce the basic physics of such systems and discuss their statistical mechanical description. A key element is the use of macroscopic measurements to identify the microscopic processes that are responsible for the form and fluctuations of driven nonequilibrium systems.
Professor Peter Kalmus OBE, Queen Mary, University of London - Antimatter - November 29th LT3
What is antimatter and where might it exist? For every type of particle there is a corresponding antiparticle. The electric and nuclear forces between two antiparticles are the same as between corresponding particles. Thus antiatoms and even antimatter in bulk might exist. However when antiparticles come into contact with ordinary particles they can annihilate each other, so antimatter would not exist for long on Earth unless it was totally isolated. We explain how particle physics could help us to avoid being annihilated by a science-fiction antimatter alien from another world. We review searches for antimatter in the universe, and describe some experiments with antiparticles on Earth.
]]>Synopsis:
In the first part of the talk, the Kochen-Specker theorem will be presented, which shows that it is not possible to assign true or false to all propositions about a quantum system at once. Thus, the Kochen-Specker theorem is a major obstacle to any naive realist interpretation of quantum theory.
In the second part, it will be shown how topos theory, which is a generalisation of set theory, does allow the assignment of truth values to all propositions, notwithstanding the Kochen-Specker theorem. The idea is to use the internal logic of a topos, which is richer than ordinary Boolean logic. A brief sketch is given of how states and propositions can be 'translated' into topos-internal structures."
Fun for the whole family!
]]>Synopsis:
In the first part of the talk, the Kochen-Specker theorem will be presented, which shows that it is not possible to assign true or false to all propositions about a quantum system at once. Thus, the Kochen-Specker theorem is a major obstacle to any naive realist interpretation of quantum theory.
In the second part, it will be shown how topos theory, which is a generalisation of set theory, does allow the assignment of truth values to all propositions, notwithstanding the Kochen-Specker theorem. The idea is to use the internal logic of a topos, which is richer than ordinary Boolean logic. A brief sketch is given of how states and propositions can be 'translated' into topos-internal structures."
Fun for the whole family!
]]>Dr Peter Török will be talking on the subject of 'Is there a future in optical data storage'.
Optical Storage: Quo Vadis?
The question quo vadis (i.e. where are you heading) has been asked many times in history. Optical storage is currently facing a fork in the road because fundamental physical principles limit the amount of data that can be realistically put on a single disk. The talk will discuss the past, present and future of optical storage including some of the work that we have been carrying out in Imperial College.
Important: If you attend please bring your credit card or a new £5, £10, £20 or £50 banknote!
]]>Dr Peter Török will be talking on the subject of 'Is there a future in optical data storage'.
Optical Storage: Quo Vadis?
The question quo vadis (i.e. where are you heading) has been asked many times in history. Optical storage is currently facing a fork in the road because fundamental physical principles limit the amount of data that can be realistically put on a single disk. The talk will discuss the past, present and future of optical storage including some of the work that we have been carrying out in Imperial College.
Important: If you attend please bring your credit card or a new £5, £10, £20 or £50 banknote!
]]>