Jun 15, GianCarlo Ghirardi, former professor of theoretical physics and then emeritus at the physics department of our university, passed away on 1st. GianCarlo Ghirardi. Angelo Bassi and Tullio Weber. University of Trieste, Trieste, Italy. Detlef Dürr. Ludwig-Maximilians University, Munich, Germany. PDF Full. Jun 4, The ICTP community is mourning the sudden passing of long-time colleague GianCarlo Ghirardi. Professor Ghirardi was associated with ICTP.

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[] My life with GianCarlo Ghirardi, a great friend, a great teacher and a great physicist

It is consequently very tempting to say that the problem we are discussing is a pseudoproblem: The first was a deep interest in the history and philosophy of physics.

As a consequence no prediction of standard quantum formalism for ghirarrdi is changed in any appreciable ggirardi. But what, in Bohr’s view, would make the diaphragm or the pointer different from other systems used to determine the states of these objects—that is the real mystery. The quantum evolution of the two states can be represented as follows: Renew your membership Member directory.

Dieter Zeh Ernst Zermelo. It is thanks to him if I learnt the foundations of this theory, and if now I am working in this fascinating field of research. For this purpose we can refer to experiments of the kind discussed in chapters 3 and 4, in which photons with definite states of polarization were sent into a birefringent crystal, and we enrich the analysis by including the dynamics of the detecting apparatus. We can ask ourselves then: It follows that the interaction between microsystem and measuring apparatus should bring about a macroscopic change of the apparatus in such a way that, by observing the state of the apparatus after the process, we would be able to obtain the desired information.

He fully deserved this recognition. It is simply random, with the probability very high in the presence of macroscopic objects. He was president of the Italian Society for the Foundations of Physics, of which he was one of the gnirardi members. Ghirardi—Rimini—Weber theory Quantum mechanics foundations. This would mean that we could no longer speak of spots in precise positions, but only of the potentiality that the film would be exposed at certain N points rather than at others.

Giancarlo Ghirardi – Wikipedia

He attended the first-ever international seminar in theoretical physics in Trieste that was organized by ICTP co-founders Paolo Budinich and Abdus Salam in the early s and has been a steady presence at the centre ever since. Where are we to place the boundary between the vague microscopic world and the precise world of our sensory ghiragdi So there must be some kind of ‘collapse’ going on in addition, to enforce macroscopic narrowness.


Jonathan Lowe John R. And we think there is nothing but the wavefunction.

This is not spelled out very explicitly. It does so in a rather vague way, at rather vaguely specified times. Inhe was giancqrlo the Spirit of Salam prize for his extraordinary contributions to the development of the International Centre for Theoretical Physics during its budding years, both at its scientific and organizational fronts.

If we want to describe which signals actually reach the brain, we would once more have to relocate the boundary between the vague quantum world and the world of definite events, and we are then led to place it between the optic nerve and the brain.

We know, they seem to say, that macroscopic pointers have definite positions. GianCarlo Ghirardi on Measurement In his elegantly written and nicely illustrated book, Sneaking a Look at God’s CardsGhirardi starts his discussion of the measurement problem by noting that the principle of superposition of states means that some observables lack a precise expectation value, so we can speak only of the probability of outcomes.

In Memoriam

For simplicity we will suppose, with von Neumann, that the photon passes through the apparatus without changing its state. The argument shows in a simple way how to realize a state of the type considered in the preceding section.

Probability of what exactly? But it must be emphasized that to account for the internal structural properties of even a simple macroscopic crystal, or the behavior of electronic chips, or the functioning of transistors, etc. Information physics identifies the boundary as the place and moment when irreversible new information enters the universe.

Physics > History and Philosophy of Physics

He was one of three authors of the so-called GRW theory, derived from the initials of its proponents: In the information physics solution to the problem of measurementthe timing and location of the Heisenberg “cut” are identified with the interaction between ghirzrdi system and classical apparatus that leaves the apparatus in an irreversible stable state providing information to the observer.


His research interests related to a variety of topics of ghirarddi physics, but focused beginning in mainly on the foundations of quantum mechanics.

Then came the Born interpretation. Nevertheless, as observed in the preceding section, this does not have any consequences for what concerns the fact that any assertion about the position of the pointer is illegitimate, and it is even not permitted us to think that it ghiardi a precise position.

But however far the wavefunction has extended, the reaction of a detector to an electron remains spotty. Considerations of KG [Kurt Gottfried] and vK [Norman van Kampen] type, on the absence FAPP [For All Practical Purposes] of macroscopic interference, take their place here, and an important one, in showing how usually we do not have FAPP to pay attention to the whole world, but only to some subsystem and can simplify the wave-function In addition to the GRW theory, added Quevedo, Ghirardi made other important scientific contributions which are less known.

But it must be noted that even this last solution is not without ambiguity. The founding fathers were unable to form a clear picture of things on the remote atomic scale.

As we have repeatedly observed and as is clearly illustrated by the equations In the case when the apparatus is set off by a polarization state that is the superposition of the states that it is programmed to register, and under the assumption that the measuring process is governed by the linear laws of the theory, one must conclude that the final state does not correspond to an apparatus with the pointer in a definite position.

Broad Michael Burke C. As discussed in Section The conclusion is clear: Scientists Michael Arbib John S. This page was last edited on 7 Juneat And so what can be wrong with this simple, clear argument? Schematic representation of a measuring apparatus with the pointer in position 0, which indicates that it is ready to register the arrival of a photon either in the upper shaded region U or in the lower shaded region L.

Bell and presented by him at two conferences: And this is in fact what we would experience if we actually looked at the apparatus.