Signals of a Strange Universe (2009 March 29)

[aristarchusinexile]

for science to succeed ( ie get answers 0 one must consider all options, even those rejected previously.

Actually, one of the main reasons that science succeeds is because there is seldom a need to consider options that have been previously rejected. That generally keeps things moving forward.

Do you mean like Einstein rejecting the Constant, Chris? (Or whatever it was he rejected and was eventually found to be necessary to his theory - my head is too full of things right now to remember stuff, if you know what I mean. Anyway .. you said, "that generally keeps things moving forward" so my input could correctly be viewed as time-wasting redundancy.

[Chris Peterson]

Do you mean like Einstein rejecting the Constant, Chris? (Or whatever it was he rejected and was eventually found to be necessary to his theory - my head is too full of things right now to remember stuff, if you know what I mean. Anyway .. you said, "that generally keeps things moving forward" so my input could correctly be viewed as time-wasting redundancy.

I mean just what I said: there is seldom a need to consider options that have been previously rejected. That doesn't mean there are not exceptions, but they are few and far between, and getting fewer as our observational abilities improve. I did not say that every previously rejected idea must be rejected out of hand, but most old ideas (the plasma universe is a good example) were rejected for good reason, and there is no compelling reason to revisit them. That's the key, of course: a reason must be compelling. If you revisit every old idea every time you consider a new theory, you'll never get anywhere. As I said, one reason for the success of science is that it is progressive with respect to understanding nature, not regressive.

Einstein's cosmological constant was rightly rejected, because it was not necessary to explain observations. Now, better observations suggest that there is something analogous at work (although not exactly the same thing at all).

[aristarchusinexile]

Einstein's cosmological constant was rightly rejected, because it was not necessary to explain observations. Now, better observations suggest that there is something analogous at work (although not exactly the same thing at all).

If the Constant is correct, its rejection was incorrect regardless of supposed observations at that time .. which reminds us of the need to be totally open minded instead of simply paying lip service to the concept of discovery, debate being much more healthy and companionable and productive as a result. Also, from what I read, as our observational abilities improve, our need to revisit rejected ideas becomes more imperative.

[Chris Peterson]

If the Constant is correct, its rejection was incorrect regardless of supposed observations at that time ..

I disagree completely. In science, the correct thing to do is to follow the evidence. If there was no evidence for this constant, it was correct to reject it. To do otherwise would essentially end scientific progress. As I noted previously, you'd be hard pressed to come up with many examples of rejected ideas that were later readopted.

[bystander]

Einstein's cosmological constant was rightly rejected, because it was not necessary to explain observations. Now, better observations suggest that there is something analogous at work (although not exactly the same thing at all).

If the Constant is correct, its rejection was incorrect regardless of supposed observations at that time .. which reminds us of the need to be totally open minded instead of simply paying lip service to the concept of discovery, debate being much more healthy and companionable and productive as a result. Also, from what I read, as our observational abilities improve, our need to revisit rejected ideas becomes more imperative.

Cosmological Constant: History

Einstein included the cosmological constant as a term in his field equations for general relativity because he was dissatisfied that otherwise his equations did not allow, apparently, for a static universe: gravity would cause a universe which was initially at dynamic equilibrium to contract. To counteract this possibility, Einstein added the cosmological constant. However, soon after Einstein developed his static theory, observations by Edwin Hubble indicated that the universe appears to be expanding; this was consistent with a cosmological solution to the original general-relativity equations that had been found by the mathematician Friedman.

It is now thought that adding the cosmological constant to Einstein's equations does not lead to a static universe at equilibrium because the equilibrium is unstable: if the universe expands slightly, then the expansion releases vacuum energy, which causes yet more expansion. Likewise, a universe which contracts slightly will continue contracting.

Since it no longer seemed to be needed, Einstein called it the '"biggest blunder" of his life, and abandoned the cosmological constant. However, the cosmological constant remained a subject of theoretical and empirical interest. Empirically, the onslaught of cosmological data in the past decades strongly suggests that our universe has a positive cosmological constant. ...

[aristarchusinexile]

Einstein's cosmological constant was rightly rejected, because it was not necessary to explain observations. Now, better observations suggest that there is something analogous at work (although not exactly the same thing at all).

If the Constant is correct, its rejection was incorrect regardless of supposed observations at that time .. which reminds us of the need to be totally open minded instead of simply paying lip service to the concept of discovery, debate being much more healthy and companionable and productive as a result. Also, from what I read, as our observational abilities improve, our need to revisit rejected ideas becomes more imperative.

Cosmological Constant: History

Einstein included the cosmological constant as a term in his field equations for general relativity because he was dissatisfied that otherwise his equations did not allow, apparently, for a static universe: gravity would cause a universe which was initially at dynamic equilibrium to contract. To counteract this possibility, Einstein added the cosmological constant. However, soon after Einstein developed his static theory, observations by Edwin Hubble indicated that the universe appears to be expanding; this was consistent with a cosmological solution to the original general-relativity equations that had been found by the mathematician Friedman.

It is now thought that adding the cosmological constant to Einstein's equations does not lead to a static universe at equilibrium because the equilibrium is unstable: if the universe expands slightly, then the expansion releases vacuum energy, which causes yet more expansion. Likewise, a universe which contracts slightly will continue contracting.

Since it no longer seemed to be needed, Einstein called it the '"biggest blunder" of his life, and abandoned the cosmological constant. However, the cosmological constant remained a subject of theoretical and empirical interest. Empirically, the onslaught of cosmological data in the past decades strongly suggests that our universe has a positive cosmological constant. ...

Good old Bystander to the rescue. So, it was Einstein's preconceived notions rather than scientific evidence of a static universe which caused him to disregard the Constant. I know I'll be repeating myself, but this is the same mindset which forms stifling thought processes for anyone beginning a study of cosmology with Big Bang, as compared with a clean slate.