Big Questions in Science: From the Very Small

to the Very LargeSebastian de Haro

AUC Open Day, 17 January 2015

The Course: Quick Introduction

• Academic core course for non-science majors

• It can be used to fulfil the science requirement

• No science background expected or required• Students with a science background (‘beta-profiel’ or similar) can still take the

course and benefit from the different perspective

• They normally provide good contributions to the class discussion!

The Teacher(s): Quick Introduction

• Three teachers, one for each section

(physics & astronomy, earth science, biology)

• My own background: Dutch/Spanish, theoretical physicist, 40 research papers, 1500 citations• Now new background in philosophy of science: second PhD at the

University of Cambridge• Interest in philosophical questions obvious in the course!

• Teacher and tutor at AUC since 2009. Courses:

• Quantum Physics, Statistical Mechanics,

Symmetries and the Quantum Universe, Philosophical Problems

The Course: More Details

• Taught twice a year (fall and spring): 50 students

• Tailor-made for AUC students’ needs in HUM/SSC• Connection to humanities/society

• Different student backgrounds

• Importance of science in everyday life

• To become a critical citizen on various issues one needs basic understanding of the state of the art of science

• Provide an overview of the very basic concepts of science fostering the development of such an understanding

• Identify the Big Questions in Science, and how these questions are being (have been) addressed

General Aims

• Basic understanding of the state of the art:• Overview of the basic concepts of science needed to understand the

Big Questions

• Identify concrete Big Questions in science, old and new:• What makes them into Big Questions?

• How do scientists address them?

• Their social/cultural impact (and impact on them!)

What the students say…

• “I really liked Sebastian's slides; they were very helpful for the exam preparation. I didn't really like the idea of 'learning questions' but it ended up being super helpful. I used to hate physics, and was surprised to have liked it so much after taking the course. It's probably thanks to Sebastian too.”

• “It's demanding for a social science student, but you learn a lot.”

Big Questions Connecting Circle:Space- and time-scales

3 Time and relativity

4 Quantum mechanics

5 Our cosmic origins

1 Classical physics

2 The Scientific Revolution

Length Scales: Powers of Ten

Documentary film Powers of Ten (9 min)

Different length scales distributed on the Big Questions Connecting Circle 10𝑛 = (1 with 𝑛 zeroes)

Examples of scientific theories distributed on the Big Questions Connecting Circle

Examples of sciences distributed on the Big Questions Connecting Circle

Newton’s Big Question

Why does the Moon not fall on Earth?

It is in constant fall but its direction keeps changing

The Moon behaves as any other physical object, for instance an apple!

The Scientific Revolution

• Copernicus vs. Ptolemais

• Kepler (laws of motion of the planets)

• Galilei (mechanics, popularisation of Copernicus)

• Newton (laws and Big Question: What is gravity?)

• What made it a revolution?• Novel science (modern science is born)

• Influence on society (‘paradigm shift’)

• Societal influences on the genesis of the revolution

Einstein’s Big Questions

• What is time and how do we measure it? (Augustine, Galilei)

• What is gravity and how does it work? (Newton)• Preliminary: energy (forms of energy, conservation of energy)

• Cultural influences (both ways): dynamism of space-time and extra dimensions in art (e.g. cubism, Flatland)

• Einstein’s mathematical derivation of the relativity of time (‘time dilation’) using only basic trigonometry!

• Theory of relativity: nice illustration of the ‘scientific method’

The General Theory of Relativity: Black Holes

• Qualitative explanation of the general theory of relativity

• Experimental evidence for the existence of black holes, predictions

Big Questions in Science, fall 2014. SdH, AUC

Quantum Mechanics: Connections between Micro and Macro

• Basic review of the history and main principles of quantum mechanics: atoms, electrons, light

• Many properties of large systems are related to quantum mechanics

Example: Spectral Lines

• Specific wavelengths of light emitted/absorbed by particular atoms

• Explained by quantum mechanics

Example: Planck Spectrum and Spectral Lines

• Explain a large number of macroscopic phenomena: colour of light, absorption of radiation in the atmosphere by greenhouse gases

• Used in astronomy to determine the distance of stars to us

• Used in cosmology to test the theory of the Big Bang

The ‘Weirdness’ of Quantum Mechanics: Schrödinger’s Cat

What is measurement? What is an ‘observer’?

Big Questions Connecting Circle:Space- and time-scales

3 Time and relativity

4 Quantum mechanics

5 Our cosmic origins

1 Classical physics

2 The Scientific RevolutionEnergy

Big Question: How Did the Universe Start? And How Do We Know This?

• … and what are OUR cosmic origins?

• Most of the matter in the universe was created shortly after the big bang (hydrogen, helium)

• But there was not enough time to form heavier atoms, from which our body is made (carbon, oxygen). This was formed inside stars!

• And then again, only 4% of the universe is made of matter

• The remaining 96%… Dark matter?... Dark energy?

The Big Bang

The Big Bang

• Time-line: what happened when, and how do we know?

• Experimental evidence for the theory

More Connections…

• Between the history of the universe and the history of science

• Not by chance!

Big Questions in Science, spring 2014. SdH, AUC

Thank you!