The Anthropic Cosmological Principle: A Universe made for me?

The Anthropic Cosmological Principle: A Universe made for me? Geraint F. Lewis Sydney Institute for Astronomy The University of Sydney

What is the “Anthropic Principle”? Universe

The Geocentric Universe

The Heliocentric Universe Nicolaus Copernicus (1473-1543)

The Heliocentric Universe Galileo Galilei (1564-1642) Brahe & Kepler (1546-1601/1571-1630)

The Clockwork Universe Isaac Newton (1643-1727)

The Milky Way of Stars William Herschel (1738-1822)

The Milky Way of Stars

The Immense Universe Hubble Ultra-Deep Field

The Copernican Principle The Copernican Principle says that we are not in a privileged location, in either space or time, and this should hold at all points in the Universe.

The Relativistic Universe Albert Einstein (1879-1955)

The Dispassionate Universe

From the first stars… Or is it? Robert Dicke (1916-1997) We could not live in the first few billion years of our universe, and could not arise after a few trillion years. … to the last.

Curiouser and curiouser….. Space Time The expansion of our universe depends upon the mix of “stuff” in it, such as matter, radiation and dark energy. If we imagine different universes with different mixes, some will collapse quite quickly, some will expand quite quickly.

The Goldilocks Universe So, our Universe appears to be a Goldilocks universe. It has the right mix of stuff, not too much to recollapse, not to little to expand too fast. How lucky we are to find ourselves in this universe nicely “designed” for us.

Whoa!! Hold your Horses “It’s rather is if you imagine a puddle, waking up one morning and thinking hmm this is an interesting world I find myself in, an interesting hole I find myself in, it fits me rather neatly, doesn’t it. In fact it fits me staggeringly well, must have been made to have me in it! This is such a powerful idea that as the sun rises in the sky and the air heats up and, as gradually the puddle gets smaller and smaller it’s still frantically hanging onto the notion that everything’s going to be alright because this world was meant to have him in it, was built to have him in it. So the moment he disappears catches him rather by surprise.” Douglas Adams Do we live on a Goldilocks Earth? A planet apparently made for human life?

Curiouser and curiouser….. Space Time At 1ns, the Universe had a density of a medium-sized asteroid per cubic centimetre. One gram more at the Universe would have collapsed before 10 billion years and we would not be here to talk about it.

… and curiouser In 1998, it was realised that the expansion of the Universe is accelerating, driven by a mysterious, dominant component known as Dark Energy The Quantum Vacuum has the right kind of properties to be the source of Dark Energy. However, the theoretically expected value is 100000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000 times larger than the observed value. Why the (ridiculously huge) difference?

… and curiouser http://www.particleadventure.org/ What if we played with the fundamental forces?: Gravitational Force Weaker: Stars would not burn, or possibly even form Stronger: Stars burn to quick, using up all of their fuel

… and curiouser http://www.particleadventure.org/ What if we played with the fundamental forces?: Electro-Magnetic Force Weaker: No atoms as electrons will not stick to nuclei Stronger: Electrons strongly bound to atoms, allowing no molecules

… and curiouser http://www.particleadventure.org/ What if we played with the fundamental forces?: Strong Force Weaker: Nuclei would not exist, with only hydrogen in the Universe Stronger: Light elements would quickly join to make iron

… and curiouser http://www.particleadventure.org/ What if we played with the fundamental forces?: Weak Force Weaker: Reduced radioactivity Stronger: Increased radioactivity, with everything becoming iron

The Goldilocks Universe If we randomly choose the mix of stuff and the forces of nature, the most likely universe we will end up with will be sterile. But our Universe, of course, has not only the right mix of stuff, but also it has the right combination of fundamental forces, none too strong or too weak, allowing stars, elements, molecules and us to form. The question is why?

The Anthropic Principle In 1973, Brandon Carter articulated these ideas in the Anthropic Principle. This has two components; Weak Principle: The fact that we, carbon-based life, are here, tells that that, while not central, we must have some privileged view of the Universe. Strong Principle: The fact that we, carbon-based life, are here, tells us that the fundamental properties are such to allow complex, intelligent life to develop. However, the question remains why? Brandon Carter (1942-)

Is this getting us anywhere? The only successful use of Anthropic Reasoning came from Fred Hoyle. As one of the first to realise the inner workings of stars, he also realised that that there was a problem in the formation of Carbon (known as the Beryllium Bottleneck). He reasoned that as we are here, and are made of Carbon, their nuclei must possess a, as yet unknown, “resonance” to allow the reaction to occur. This was searched for, and found, where Hoyle said it should be.

Option 1: Fine Tuned/Just the Way it is! “I don’t pretend to understand the Universe, it’s a great deal bigger than I am” Thomas Carlye (1795-1881) A divine creator Or not?

Option 2: An Underlying Beauty? Perhaps the dimensions of space and time, the forces of nature and the fundamental particles are linked and there is no underlying freedom in the Universe. Our current attempts of a Theory of Everything suggest that this is not the case.

Option 3: A Many-Worlds Universe Many-worlds is an idea from quantum mechanics, with the idea that every time a “decision” is made, the universe splits into two universes, each with a different outcome of the choice. Most universes would become sterile, but we would find ourselves only in that small number of universes that preserve life.

Option 4: The Multi-verse The early universe had a burst of expansion called inflation. With this, different patches of the universe have their initial properties “frozen-in”. This means that many patches of the Universe are sterile, but, of course, we should expect to find ourselves in a patch whose properties can support life.

The Superstring Landscape The “cutting-edge” of physics has the goal of unifying general relativity and quantum mechanics. One of the leading contenders, string theory, has a huge (infinite?) possible combination of physical parameters (and hence and huge number of possible universes). But which is the combination in which we live in? Physicists are turning to the anthropic principle to narrow down the huge volume. Will this solve the issue?

The Controversial Anthropic Principle Published in 1986, Barrow and Tipler’s book pushed the meaning of the Anthropic Principle; Weak Principle: All properties of space and time must be consistent with the existence of carbon-based life (including the number of dimensions etc). Strong Principle: A Universe with these properties (i.e. our Universe) must develop intelligent life at some point in its history.

The Objectors Every time the anthropic principle is raised, arguments ensue, with the point that (other than Hoyle’s work) the anthropic principle has explained nothing. Does it really give us clues to the underlying nature of the Universe?

Anthropic Weirdness Self-Reproducing Universe Final Anthropic Principle (FAP)

Anthropic Weirdness Completely Ridiculous Anthropic Principle (CRAP) Self-Reproducing Universe Final Anthropic Principle (FAP)

So, where are we… Lynette Cook The anthropic principle is an interesting concept, confronting our basic ideas in understanding our place in the Universe. But does this tell us anything we didn’t know about the Universe, or allow us to deduce why our Universe is as it is; to some yes, to others, no. In either case, we have not heard the end of the Anthropic Principle.

So, where are we… The End Lynette Cook The anthropic principle is an interesting concept, confronting our basic ideas in understanding our place in the Universe. But does this tell us anything we didn’t know about the Universe, or allow us to deduce why our Universe is as it is; to some yes, to others, no. In either case, we have not hear the end of the Anthropic Principle.

Particle Astronomy – the Second Window by Dr Marc Duldig, Australian Antarctic Division14 October – 6.00pm Bankwest Theatre (Building 200), Curtin University of Technology, BentleyRSVP is essential. Please respond by Friday 9 October 2009 by phone: 08 9266 2563 or email: events@curtin.edu.au

The Anthropic Cosmological Principle: A Universe made for me?