Why We Think There's a Multiverse, Not Just Our Universe 458
An anonymous reader writes "It's generally accepted that the Universe's history is best described by the Big Bang model, with General Relativity and Quantum Field Theory as the physical laws governing the underlying framework. It's also accepted that the Universe probably started off with an early period of cosmic inflation prior to that. Well, if you accept those things — as in, the standard picture of the Universe — then a multiverse is an inevitable consequence of the physics of the early Universe, and this article explains why that's the case."
multiverse vs time travel (Score:1, Interesting)
A common theory of time travel is that you can only time-travel between universes via DAG (directed, acyclic graph). This resolves the grandfather paradox, because it's impossible for you to go back in time in your original universe and kill your original grandfather. In other words, you were born in a universe where another you didn't travel back in time and kill your grandfather.
Re:Not the quantum mechanical multiverse (Score:5, Interesting)
And, since you might RTFA and I am certainly too lazy, are they proposing differing cosmological constants for these various regions, or more or less identical universes just starting with a different energy soup?
Words, words (Score:5, Interesting)
I think that this is a great article, but...
It is obvious that there are parts of the universe that are not (and never have been) causally connected with our universe.Those are just the parts of our universe we can't see, which are inevitable in an infinite universe with a finite duration and a finite speed of light. You don't need either quantum mechanics or inflation for that, and it has never been called the "multiverse."
The multiverse in my experience means exclusively the idea that there are other parts of the universe with different physical laws. That idea is connected to the anthropic principle, and (IMHO) evading tough issues about the nature of physical laws. (Find the cosmological constant to be inconveniently small? That's OK! In a multiverse there are a gazillion universe with large cosmological constants and no life like ours, ours with a small one and our kind of life, and nothing left to explain!) "We" might think that there is that kind of multiverse, but "we" in this case decidedly does not include "me." (People like me tend to call such ideas "Just so stories," which in physics is an insult.)
I guess that's ok (Score:5, Interesting)
I mean, I can handle the concept... so long as there's just ONE multiverse.
Observable universe (Score:5, Interesting)
I thought there were already concise terms for it. The universe IS the multiverse / partitioned universe. The part that we are in is called observable universe.
Re:Actually... (Score:4, Interesting)
Really things were set up rather well initially. But it broke down almost immediately.
The big problem was that we let the government reinterpret their own rights.
So the executive gets executive privilege which lets them basically lie/keep secrets from the legislature/judiciary and through interpretation the judiciary gets legislative powers by getting the power to change the meaning of laws.
There are other examples but they're all perversions.
The Executive has no right to keep secrets of any kind from the legislature or the judiciary... these are interpreted powers.
The Judiciary assumed the right to interpret laws because how could they rule on the constitutionality of a law if they couldn't strike one down. The issue becomes especially thorny when they start reinterpreting the constitution itself which is the highest law in the land.
In regards to how these two compromises should have broken down:
1. Give the Judiciary and legislative branch a joint investigative power over the Executive that reports to either the full house or the select committees as desired by the Legislative. The Judiciary likewise can receive the reports however they like. But a major flaw in the system is that the executive is the only branch allowed to directly investigate anything. Which means when it needs to be investigated there is a conflict of interest. Hold executive funds in bank accounts controlled by the legislative so that their checks literally bounce the instant the legislative branch desires it. And the Judiciary can pull legal authority from the executive if it fails to comply... so a government order to X by the executive would suddenly lack all legal authority if the executive stopped complying with the Judiciary.
2. In regards to Courts assuming legislative powers the courts have a point that they need the power to modify laws however those powers have been pushed far too much. All they really need is to say "rewrite this bill because it conflicts with X". Or in the case that there is a Constitutional law that needs clarification, simply cite precedence on the law and if required request a law from the legislature that addresses the case specifically. In that way, the courts wouldn't be legislating but rather pointing out a problem to the legislature and requesting their clarification on the issue.
In any case, your idea reminds me of Frank Herbert book. I think it was "the Whipping Star"... In this future society there is an American type governmental system with the three conventional branches but there is also a fourth branch called "bureau of sabotage" which has the sole function of screwing up government. Mostly slowing it down, frustrating it, cocking it up, leaking information... generally making things not work very well. The theory being that government becomes a problem when it becomes efficient and a confused and hamstrung government is less ambitious and more solicitous of its citizens. The government is always kept on the brink of collapse so if the government ever loses the consent of the governed it will fold instantly.
Its an insane idea but its also an amusing one in these times of rampant government arrogance.
Re:My God... (Score:5, Interesting)
+5 Inisghtful?
"the theory does not predict anything,"
Wrong.
1) The universe is close to flat
2) Regions that are currently causally disconnected were connected in the past - implying that both sides of the sky can exist at the same temperature
3) There are unobservably few magnetic monopoles even if such monopoles can exist
4) The primordial power spectrum of cosmological perturbations was almost, but not quite, Harrison-Zel'dovich
5) There is a relic background of primordial gravitational radiation
6) There is very litte primordial vorticity; observed vorticity has arisen through later processes
etc.
1, 2, 3, 4 are observably verified, by such experiments as COBE, Boomerang, WMAP, Planck, 2dF, SDSS, WiggleZ and their like. 5 is likely to be verified or rejected in the next year or two. 6 is currently very safely within bounds and looks far the most sensible explanation.
"no experience can be done to test it."
Wrong, though arguable if you insist on "testing" rather than "observing". In this context they're the same thing -- make a theory, make a prediction from said theory, and then find an observation to test it. For instance, ekpyrosis is likely to die in the next year or two since it predicts zero primordial gravitational radiation. But if you want to wank about definitions of words (which in my experience has been the practice of those with limited education in the field) be my guest; you can certainly argue it can't be "tested", even while the professionals are, um, testing the theories.
"In other words, this is faith."
No it is not. It is founded on a pair of solid theories -- general relativity and quantum mechanics -- and on a method of tying aspects of those theories together. The limitations are well known and well explored and the techniques are mathematically solid. Whether the physics is being applied the right way is a totally different question, but that's a matter for experiment and observation to determine, not one of "faith". I'm not suggesting for one moment that too many cosmologists haven't been educated into a theory that is far shakier than they believe, because they have, but even that isn't faith. It's merely a sign that we're overspecialising our cosmologists... and that there are no credible alternatives anyway, including from the likes of myself who have attempted to pursue fundamental issues at the heart of cosmology. A "credible alternative" explains all the data at least as well as a standard inflation+dark energy+cold dark matter big bang cosmology. There is a hell of a lot of data, and LCDM fits practically all of it remarkably well. Can't say that for almost any alternative.
"there is always something wrong when you confuse it with science"
No argument from me here, but it's not me getting confused.
Re: You mean (Score:5, Interesting)