Category: Past colloquia

Our last online Physics Colloquium for this autumn will take place on Friday, December 10th. We will have an inaugural lecture to be given by Hannu Kurki-Suonio, who recently got promoted to Full Professor in our department.

Hannu obtained his PhD from the University of Texas in 1986 and worked in the USA for several years before returning to Helsinki. He has been a University Lecturer at the University of Helsinki since 2001, and in 2021, he became Professor of Cosmology at the University of Helsinki. He was strongly involved in the former Planck mission from the European Space Agency, for which he was one of the four Finnish Co-Investigators. Hannu now leads the Finnish participation in the upcoming Euclid mission and represents Finland in the Euclid Consortium Board.

In this colloquium, titled Euclid space mission: Is the acceleration of the expansion of the universe caused by dark energy?, Hannu will tell us about this upcoming cosmology mission and the scientific objectives it aims to address.

The event will be held on Friday 10.12.21 at 14:15, on Zoom (Meeting ID: 660 6869 4076 – Passcode: 587666).

Here is his abstract:

The next cosmology mission of the European Space Agency is Euclid.  It is a wide-field space telescope, to be launched in 2023 to orbit the second Lagrange point of the Earth-Sun system.  In six years it will observe 36% of the sky, measuring the distribution of galaxies and dark matter in the universe.  The mission is optimized for helping to solve the “dark energy problem”: What causes the observed acceleration of the expansion of the universe?  Is it a new energy component, “dark energy”, filling the universe, or should the law of gravity be modified at cosmological distances? What is the more detailed nature of this dark energy or modification of gravity?  To help theorists towards the correct solution, Euclid measures the expansion history and growth of large-scale structure to much higher accuracy than is currently known.  The tools for this measurement are the statistical properties of the galaxy distribution and the gravitational lensing of galaxy images by dark matter.

Since looking over longer distances means looking further back in time, Euclid will trace the last 3/4 of the 14-billion-year history of the universe.

Euclid complements the previous ESA space mission, Planck (2009-2013), which focused on the early universe, in improving the understanding of the structure and history of the universe.  Finland contributes to the Euclid mission by providing one of the nine Euclid science data centers to analyze Euclid data.

Our next online Physics Colloquium for this autumn season will take place on Friday, November 19th. Our speaker will be Hanna Kokko from the University of Zurich, in Switzerland, who will talk about her current research in evolutionary biology.

Hanna Kokko obtained her PhD from the University of Helsinki in 1997 on the topic of sexual selection. She currently is a full professor in evolutionary ecology in the Department of Evolutionary Biology and Environmental Studies of the University of Zurich, where she leads a team working at the crossroads between evolutionary biology and ecology. Drawing from her initial background in applied mathematics and engineering, she is particularly interested in the mathematical logic that underpins biology. Her research interests include the evolution of reproductive and social strategies, as well as sustainability science.

In this colloquium, titled If evolution is all about the survival of the fittest, how come it produces so much diversity?,  Hanna will talk about the role of natural selection in the diversity of species.

The event will be held on Friday 19.11.21 at 14:15, on Zoom (Meeting ID: 655 7001 8701 – Passcode: 534720).

Here is her abstract:

If one thinks of evolution by natural selection as a process that weeds out poorly performing genotypes and filters out the good ones, one can rightfully express wonder at the fact that there is not one best solution that has taken over everywhere. I will discuss three case studies (Daphnia waterfleas, Gouldian finches, and a marine midge) that highlight how and why diversity in behaviours and/or strains of organisms can be maintained by natural selection.

Our next online Physics Colloquium for this autumn season will take place on Friday, October 22nd. Our speaker will be Andrzej Kotarba from the Jagiellonian University in Kraków, Poland, who will present his research on nanomaterials and biotechnology.

Andrzej Kotarba is full professor at the Faculty of Chemistry of the Jagiellonian University. He set up the Materials and Surface Chemistry Group at the Jagiellonian University in 2005. The research carried out in the group is focused on the processes taking place at the solid/gas and solid/liquid interfaces, with the aim to apply the acquired knowledge in designing surfaces with desired properties and functionalities. It includes the preparation and characterization of model carbon-based surfaces, catalysts and biomaterials and involves interdisciplinary studies at the border of chemistry, nanobiotechnology and materials science. Andrzej is also an editor of Applied Surface Science.

In this colloquium, titled A new paradigm in the fabrication of functional nanomaterials: let bacteria do the job, Andrzej will describe how microorganisms could be utilised in materials science.

The event will be held on Friday 22.10.21 at 14:15, on Zoom (Meeting ID: 621 4476 0356 – Passcode: 781892).

Here is his abstract:

Despite dynamic progress, the art and science of functional material preparation still remain centre stage. The innovatively prepared materials using nonpathogenic bacteria to capture nanoparticles and deposit them on various supports by leveraging the microbial “race for the surface” is proposed. It is demonstrated that bacteria are effective biocarriers for the capture, transport, and controlled dispersion of nanoparticles on support surfaces. Next, the bacteria are effectively removed with oxygen plasma or transformed into a carbon film of various compositions and morphologies. The conceptual proposal is substantiated by a feasibility study showing successful preparations of various functional materials via the use of microorganisms.

Our first online Physics Colloquium for this autumn season will take place on Friday, September 17th. Our speaker will be Minna Palmroth, who will talk to us about the recent discovery of a new auroral form, enabled by citizen scientists.

Minna is Professor in Computational Space Physics at University of Helsinki and the Director of the Finnish Centre of Excellence in Research of Sustainable Space. Her research work combines magnetospheric physics and high-performance computing, as she is leading the development of one of the largest supercomputer space physics models.  In 2018, she published a popular science book about the aurora, Revontulibongari opas, which features pictures from aurora hunters all across Finland. This book was the first step to an unexpected scientific collaboration.

In her colloquium, titled Citizen scientists discover a new auroral form: Dunes provide insight into the upper atmosphere, Minna will talk about the journey leading to this discovery and the scientific implications of the citizen scientists’ findings.

The event will be held on Friday 17.09.21 at 14:15, on Zoom (Meeting ID: 679 5239 0566 – Passcode: 036512).

Here is her abstract:

Auroral forms are like fingerprints linking optical features to physical phenomena in the near-Earth space. While discovering new forms is rare, recently scientists reported of citizens’ observations of STEVE, a pinkish optical manifestation of subauroral ionospheric drifts that were not thought to be visible to the naked eye. This talk tells an exciting story of a citizen science project that led to the discovery of a new auroral phenomenon. Dunes are a horizontal stripes in the green aurora, and are currently thought to originate from the oscillation of the underlying atmospheric density. On Oct 7, 2018, citizen observers took multiple digital photographs of the same dunes simultaneously from different locations in Finland and Sweden. We develop a triangulation method to analyse the photographs, and conclude that the dunes are a monochromatic wave field with a wavelength of about 45 km within a thin layer at 100 km altitude. Supporting data suggest that the dunes manifest atmospheric waves, possibly mesospheric bores, which are rarely detected, and have not previously been observed via diffuse aurora, nor at auroral latitudes and altitudes. The dunes present a new opportunity to investigate the coupling of the lower/middle atmosphere to the thermosphere and ionosphere. We conclude that the the dunes may provide new insights into the structure of the mesopause as a response to driving by ionospheric energy deposition via Joule heating and electron precipitation. Further, our paper adds to the growing body of work that illustrates the value of citizen scientist images in carrying out quantitative analysis of optical phenomena, especially at small scales at subauroral latitudes. The dune project presents means to create general interest towards physics, emphasising that citizens can take part in scientific work by helping to uncover new phenomena.

Our last online Physics Colloquium for this spring season will take place on Friday, May 7th. We will have an inaugural lecture to be given by Emilia Kilpua, who recently got promoted as Full Professor in our department.

Emilia is an expert in solar-terrestrial physics, and her work focuses on solar eruptions and their impact on near-Earth space. She obtained an ERC Consolidator Grant in 2016 to develop novel simulations to better understand these processes, and is currently also the coordinator of a Marie Sklodowska – Curie Action Innovative Training Network on space weather. She is actively involved in multiple space missions, such as NASA’s Parker Solar Probe and ESA’s Bepi-Colombo and Solar Orbiter.

In her colloquium, titled The Art of Predicting Space Weather, Emilia will talk about the challenges of forecasting the conditions in space around our planet and in our solar system.

The event will be held on Friday 7.05.21 at 14:15, on Zoom (Meeting ID: 614 1662 5342 – Passcode:  844713).

Here is her abstract:

Like normal weather, space weather can be calm or stormy. During big storms near-Earth space experiences dramatic changes; the magnetosphere surrounding our planet gets compressed, electric currents in the magnetosphere and ionosphere intensify and fluxes of high energy particle can rapidly increase by several orders of magnitudes. Vulnerability of modern society to space weather has made forecasting it increasingly important. The quality of predictions is however still very modest. This talk presents the key factors why forecasting space weather is so challenging, and discusses the recent and future steps in the scientific understanding of solar eruptions that are most crucial for improving the predictability.