My new cosmology paper is out!

My latest paper in cosmology is now public! It took many years to write, as it was a single author side-project on a subject that is very different from my main field. My PhD was indeed in particle cosmology, while now I am mostly working on building physics and methods for energy saving in buildings. I am however still relatively active in theoretical physics, and this is meant to be the first article of a comeback into the field.

Here is the abstract:


In the framework of MSSM inflation, matter and gravitino production are here investigated through the decay of the fields which are coupled to the udd inflaton, a gauge invariant combination of squarks. After the end of inflation, the flat direction oscillates about the minimum of its potential, losing at each oscillation about 56\% of its energy into bursts of gauge/gaugino and scalar quanta when crossing the origin. These particles then acquire a large inflaton VEV-induced mass and decay perturbatively into the MSSM quanta and gravitinos, transferring the inflaton energy very efficiently via instant preheating.
Regarding thermalization, we show that the MSSM degrees of freedom thermalize very quickly, yet not immediately by virtue of the large vacuum expectation value of the inflaton, which breaks the SU(3)C×U(1)Y symmetry into a residual U(1). Compared to the case of LLe-type inflaton previously studied, we find an even more efficient energy transfer to the MSSM quanta, due to the enhanced particle content of the supersymmetric (SUSY) multiplet that is coupled to the flat direction. Full thermalization is achieved indeed after only O(40) oscillations.
We also compute the gravitino number density from the perturbative decay of the flat direction and of the SUSY multiplet. In agreement with the literature, the inflaton produces a negligible amount of gravitinos and does not raise any cosmological issues. On the contrary, the fields to which it is coupled are responsible for a severe gravitino overproduction problem, which is caused by their large VEV-induced effective masses. We argue that possible solutions might include non-coherent oscillations of multiple flat directions or fragmentation of the inflaton condensate with formation of Q-balls.


Bass playing video – Ibanez SR1405T

Hi everybody!

I’ve just posted a video of me playing the Celesti Alliance song “The Alliance” with my brand new Ibanez SR1405T (a wonderful instrument!). Straight into the amp and in passive mode, the signal chain is ridiculously simple: bass->cable-> Johnson Standard 30B amp. I didn’t even use my Seymour Duncan Studio Bass compressor, I wanted the sound of the instrument to come out as transparent as possible.
Of course, since the sound is recorded directly by the inbuilt mic of my camera, it is far from being Hi-Fi, but this gives the idea of how good this bass sounds even with low end gear, without any production.
Check it out and like it if you like!

I joined the Alliance!

*Bass rolls* I’m pleased to announce that I joined the Alliance! Celesti Alliance is an excellent heavy metal band, where I’ll be on bass duties with my loyal Jean Pierre.

Check the website and the songs from the EP Eagle’s Nest, those are really good tunes! The first gig will be very soon at Bar Rock Bear in Vantaa, on Sept 2nd. I’m actually learning the tracks and getting well into shape with my fingers, this will definitely be a good challenge for my stamina with fingerstyle 😀 I will keep a picture of Steve Harris in my bass case.

More dates (in Finland and abroad) are going to be confirmed soon, check my Live section for updates.

Mozart Medley now published!

Here you see released on my Soundcloud the first recording for my solo project “Rock Me Amadeus”! It’s a robust rearrangement of some of Mozart’s immortal compositions, featuring extracts from Symphony n.25, Eine Kleine Nachtmusik and the Queen of the Night Aria.
I recorded all the strings (and also flutes, horns and oboes) with my electric guitars (Yamaha Pacifica 611HFM, RGX 521 and Hamer Californian).

A very challenging and instructive process, first of all tonewise but mostly because it didn’t reduce to merely playing some already written parts. Even for the comping it wasn’t always a one-to-one correspondence; for the lead guitar, I had to choose which instruments to transpose and, more importantly, how to provide the lead parts with a more personal rock/metal style.
It’s just a pity that the fully digital recording kills some of the dynamics.
The next track of the project will be Vivaldi’s Winter (first movement), hopefully ready by the end of 2016 (since I now joined the band Celesti Alliance on bass).

Are there any issues in contemporary science and engineering?

“Are theoretical researches based on oversimplified methods which return wrong predictions? Do empiric approaches lack rigour and scientific depth? Is there any gap between theory and practice, and why?”.

Through our academic work, me and my colleagues at the Department of Civil and Structural Engineering, Aalto University, have noticed that far too often, separation of research fields and approaches results in uncorrelated work with inconsistencies and delays. This is responsible for both loss of resources and stagnation of research, which do exist in several fields. The same seemingly happens in education, as very often the students either use “cook book recipes” blindly, with no formal understanding, or dwell into the theory, with no insight of the real phenomena.

We argue that the root cause for a major part of the problems in construction engineering and management lies at the level of inappropriate choices and interpretations related to philosophy of science. Tracking this back in time, we found clues starting from the Platonic and Aristotelian contrasting approaches.

In the talk here attached I am sharing some thoughts on philosophy of science, which we are going to include in a paper now in phase of completion. Although civil engineering is our main concern, the full analysis we perform is fairly general; our results apply indeed to many other fields of engineering, and to science and technology as well (from which the title of this blog entry).

I have given this short talk (7 slides) at an Aalto workshop which took place last June. I review very synthetically the central ideas of Plato and Aristotle, and their fundamental impacts on the philosophy of science. My seminar evolves around the very basic principles of their traditions, explaining how they influenced the fundamental work of Descartes, Spinoza, Leibniz on one side, and Locke, Hume and Berkeley on the other. I also briefly mention Carnap, Popper and Feyerabend, due to their original contribution to epistemology (I deliberately avoided addressing Kant, as I will include him in a future entry on this topic).

I am not a philosopher, thus it doesn’t get too technical and everybody can understand it 🙂

Here it is: Philosophy of science: Plato vs Aristotle

P.S.: the title is set to “Plato vs Aristotle” as a necessary oversimplification: Aristotle was a disciple of Plato, and as such he maintained a deductive component in his induction-grounded science; so the opposition is not as radical and definitive as in Rationalism vs Empiricism.

A lecture on European climate

Here you can find the pdf of my traditional introductory lecture on European weather and climate, for our Master’s level course Building Physics Design I at Aalto University, Espoo (Finland):

European Climate

If you are curious about  weather and climate, and willing to go beyond the stereotypes to see evidence that

– cold weather is not strictly related to latitude

– the Alps are more rainy than Benelux

– Italy can be colder than Finland

take a look at the pdf, which contains a study I did last year. Enjoy 🙂