I think that most people think about the physical universe as one huge cube or sphere, filled with space-time, dark matter and dark energy, like the air in a balloon. The air of that 'balloon' however is polluted with billions and billions of galaxies. Somewhere in that balloon is our tiny earth from which we are observing everything and making smart conclusions so that we finally became able to understand the universe from its inception: the Big Bang. We even know what will happen to the universe in a few billion years. It's hard to check whether there has ever been a Big Bang. ( Physicists working in branches where results are verifiable are very modest. Think about weather predictions, and engineering another moon-mission: it would take decades. )
In popular science documentaries they bring us to 'the end of the universe', show us pictures of stars in faraway galaxies in extreme quality. How do they do that? It's not that the pictures are sent to us from that remote galaxy, they are taken from Earth('s orbit). Basically, data is captured, analyzed and processed. From that data a picture is generated: call it "probabilistic photography". ( It helps funding research if you can show some beautiful animations or pictures. What they really have though is a database with numbers. )
Physicists speak with authority and certainty about the Big Bang and the topology of the universe. That certainty is a pose, absolutely nothing is certain in physics.
I got kicked out of class once. Because I kept asking the physics teacher about gravity. "What -is- gravity?", ( I honestly didn't know that he couldn't have a clue at that time. ) I asked, when he started again about the g. constant. "Sir, -why- do objects fall to the ground?" Finally, he literally kicked me out of class.
To the point. I made two images.
Imagine that this is an abstraction of what we really know about the universe. The following image shows the same objects but from another viewpoint.
What is our viewpoint in relation to the vastness of what is around us? Does the topology of the universe permits us to see it all? Is the topology of the universe like that balloon or is it, perhaps, some topology not even discovered in the realm of mathematics? Would we ever be able to determine that?
Compare us with little intelligent tiny fish on the bottom of the ocean 'studying' the(ir) universe. What would their conclusion be?
Interesting! And thought provoking.....
ReplyDeleteNilo the way you portray it is as if physicists just come up with their theories with no basis in empirical data or correlation between models of astrophysical phenomenon and experimental data.
ReplyDeleteThe evidence for the big bang is based on three key observations
a) Hubbles observation that the galaxies are moving away from us causing a red shift in the spectra
b) Penzias and Wilson's observation of a uniform microwave background radiation
c) The observation that the relative abundancies of Helum to Hydrogen in the universe is about 23.6%
From a theoretical point view, Peebles and others showed that the abundancies could not be predicted from other cosmological theories such as Hoyle's steady state theory.
Furthermore from a topological point of view Hawking and Penrose showed that if General relativity is correct then there must be an initial singularity.
The point is that it isn't 'we just make this up because we feel like it' the reason why physicsits think the current big bang cosmology is a reasonable approximation which fits the experimental facts and so far no other theory has been as successful.
Try and get hold of Weinberg's first three minutes if you want an overview. Alternatively if you want the real thing get his latest book on Cosmology.
As always a very interesting comment, Chris. I'll reply soon. - I have fallen behind on replying to comments since I stopped moderating comments. A service to the reader, I thought. Maybe I should activate moderating again because I see that spammers found their way into the comments as well. - Or, perhaps I spend too many time on Stack Exchange.
DeleteKind regards,
nilo