Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 26/01/2012 11:22:09
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Firstly, I love the podcast. It's the right blend of basic facts blended with complex concepts which keep the amateur astronomer and scientist like me entertained, educated and never patronised. Thanks for all the ear candy for the last year and more I've been listening.
One of the basic assumptions of cosmology is the laws of physics as we know them hold true throughout the observable universe. What evidence is there for this?
Thanks again.
Brian
Asked by Brian Shelf
Visit the webpage for the podcast in which this question is answered. (http://www.thenakedscientists.com/HTML/podcasts/astronomy/show/20120125/)
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We answered this question on the show...
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I agree that the "Laws of Physics" should apply universally. However, it would be quite presumptuous to think that we now know all of the "laws of physics". Undoubtedly, some of our interpretations will be improved over time.
There are some places that it is difficult for us to observe interactions. For example 6,000 km below the surface of the Earth, or in the middle of the sun. Although, perhaps we can reproduce some of the conditions that one would expect to find, as well as build models based on known properties. Larger stars might in fact, have even different internal properties than our own sun.
Likewise, while the existence of Black Holes has apparently been confirmed, we certainly have no direct observational knowledge about the state of matter inside of the black holes, or a great explanation for the apparent escape of matter from some Black Holes.
Also, while some astronomical phenomenon such as worm holes can be mathematically modeled, it does not mean that they in fact exist.
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This is a simple question with a very complex answer and a simple one. --- Yes, but ... There is a hint that there might be a very tiny change in a critical relationship right back just about as far as we can see at the moment. More of that a bit later.
Firstly you need to specify what you mean by "the laws of physics" There are two sorts of laws of physics and one important proviso.
Firstly, there are laws like the laws of thermodynamics and in particular the second law (the one about entropy increasing that most people don't really understand) these describe fundamental ways in which things interact and would be true in any universe and are bound to be true except for the proviso.
Secondly there are laws linked by some sort of physical constant like the velocity of light or the gravitational and electrostatic and electromagnetic constants. Now these constants are in a sort of way arbitrary and could in theory change so these are the laws that might change under different conditions.
Finally the proviso. This is the uncertainty principle this defines a sort of noise floor where things start to get inaccurate and under certain high temperature and energy conditions the laws may become indistinct or even vanish.
This is where the law that might show signs of a very slight variation comes in. This is the fine structure constant and describes very fine energy level changes in the spectrum of electrons in atoms caused by the relationship between Planck's constant, the speed of light, the charge on the electron, and the electromagnetic constants and is an extremely sensitive test of any deviation in the values of these critical constants and can in effect be measured in the spectrum of the remotest stars and galaxies.