Public Astronomy Talk: Nature of the Universe by Prof George Ellis

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The nature of the Universe: What we know and what we don’t know

Our ancestors looked up at the sky and asked questions about our existence in the universe, as we do today. We now know that the universe is very old and very large, and is changing with time. It has evolved from a very small size in the distant past to its present size, with a succession of physical processes leading to structures emerging at many scales. Precise astronomical data attained by many telescopes confirms this solid understanding. But there are key issues that are not understood. What is the nature of dark matter? Of the dark energy underlying an accelerating expansion rate at recent times? What physics underlies its dynamics before the Hot Big Bang epoch? Why is there a Hubble tension? Is there an age problem? Other issues are, Why is vacuum energy as small as it is? How did quantum fluctuations lead to classical structure? We don’t know the spatial topology of the universe, or if it is spatially infinite. Above all, we don’t know how it came into existence, nor why it allows any life at all to exist. I will claim that the future of the universe is not yet determined yet, and no, we don’t live in a simulation.

Following the talk, there will be a Cultural Exchange Evening featuring a celebration of cultural astronomy through storytelling, poetry, song, and dance.

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