| From: Alan | 12/03/2000
18:14:00 |
| Subject: The laws of physics | post id:
45904 |
| Who or what decided that the
universe would have the very physical laws we live with? In the next (possible) Big Bang, will the next universe have different physical laws? | |
| From: Rapunzel | 12/03/2000
18:32:00 |
| Subject: re: The laws of physics | post id:
45923 |
Omigod, is this the beginning of another monster? Alan, have you done your lit review for this one? There are several threads in the archive on the laws of physics. There is a more recent thread called evolution which may be helpful. Also the oranges thread could be of interest. I'm yet to be convinced that we can conclude that the laws of physics are exactly the same throughout this supposedly infinite universe... (*Bite, James, bite!!! Heehee!*) For instance, do the laws of physics as we know them apply inside singularities? And even if they do: If time and space can be different elsewhere, why shouldn't the laws of physics theoretically be able to show variation in different areas of this vast place called the universe? Why should you require a different universe to have a different set of laws? And here we get back to the murky problem of what exactly a law of physics is... a description? an intrinsic property? etc. Have fun, everyone... | |
| From: Grant¹ | 12/03/2000
19:56:00 |
| Subject: re: The laws of physics | post id:
45964 |
For instance, do the laws of physics as we know them apply inside singularities? I wouldn't have thought so as they (the laws)require the 4 (or so) dimensions we have in order to be valid. I thought a singularity is where all 4 dimensions become one, so the conditions for our "laws" to apply just don't exist. | |
| From: James Richmond (Avatar) | 15/03/2000
12:20:00 |
| Subject: re: The laws of physics | post id:
46856 |
| I'm yet to
be convinced that we can conclude that the laws of physics are exactly the
same throughout this supposedly infinite universe... (*Bite, James,
bite!!! Heehee!*) Ok, I'll bite. Firstly, the universe may not be infinite in size, though the most recent data suggest that it is. Even if it is infinite, the amount of matter contained in the infinite space is finite. The laws of physics could be different in different parts of the universe, but there is currently no evidence to suggest that this is the case. When we look out into space (and back in time) we see galaxies doing things in much the same way that they are doing things today. The light from distant stars displays the same atomic spectra as the light from nearby stars, and so on. For instance, do the laws of physics as we know them apply inside singularities? The "laws as we know them" break down in singularities. Singularities no doubt have laws, too, but we don't know what they are yet since we lack a theory of quantum gravity. In all cases we are aware of, no information can leak out from a singularity to the outside universe. There is a hypothesis known as cosmic censorship which postulates that all singularities are cloaked by an event horizon - no "naked" singularities can exist. This means that any weird stuff happening inside singularities cannot affect us. Why should you require a different universe to have a different set of laws? You wouldn't, necessarily, but I'd be very surprised if the laws differed in different parts of the universe. And here we get back to the murky problem of what exactly a law of physics is... a description? an intrinsic property? etc. I've discussed this before, so I won't say anything about this now. JR | |
| From: Chris (Avatar) | 15/03/2000
13:15:00 |
| Subject: re: The laws of physics | post id:
46872 |
Why should you require a different universe to have a different set of laws? You wouldn't, necessarily, but I'd be very surprised if the laws differed in different parts of the universe. The very real problem with having different laws of physics in different parts of the universe is that at some stage in the distant past the universe was very much smaller. This makes it very difficult to sustain separate areas of the universe with separate, or competing basic rules. Now that Guth and succeeding cosmologers have been able to solve the horizon problem and link communicability in the early universe it is even harder still. In other words, it is very very difficult to sustain regions of the universe with different bases which can communicate with each other. This is because that would require boundary conditions or some uniform or continuous change. Inflationary theory allows that most, if not all, of the very early universe would have been able to communicate before inflating to distances where light speed can produce horizons. Given that, the only possibility for variation in the laws would be if they had evolved or changed with time differently in different pockets of space-time. Very unlikely. For one, we have observed no drift with base fundamentals in our observations of the distant universe. For two, large scale homogeneity, which inflation allows, rules out locally influenced divergent evolution of laws. As far as singularities are concerned, the laws of physics deal with them perfectly well. We are simply yet to discover that description. Hope this helps! Chris | |
| From: Rapunzel | 15/03/2000
16:21:00 |
| Subject: re: The laws of physics | post id:
46937 |
As far as singularities are concerned, the laws of physics deal with them perfectly well. We are simply yet to discover that description. We science staff had a bit of a talk about this here over lunch. Isn't that a statement of faith? Unless of course any law of physics is seen as a description rather than an inherent property. Then you know you could have a description, even if that differs from descritions elsewhere. If that makes any sense? | |