Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
3 online now:
Newest Member: popoi
Post Volume: Total: 915,818 Year: 3,075/9,624 Month: 920/1,588 Week: 103/223 Day: 1/13 Hour: 0/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   No Big Bang--Just gentle whisper
Son Goku
Inactive Member


Message 32 of 100 (362142)
11-06-2006 12:01 PM
Reply to: Message 23 by nwr
10-30-2006 12:32 PM


Re: Back to the drawing board
nwr writes:
That said, I am still myself a bit of a skeptic regarding BB. That's mainly because I don't think there is yet enough evidence.
Which version of the Big Bang do you remain skeptical of?
I understand some versions are still a bit too unsupported for some/most people.
For instance would you think that the statement "The universe has been expanding for the last 12 billion years" is well enough supported.

This message is a reply to:
 Message 23 by nwr, posted 10-30-2006 12:32 PM nwr has replied

Replies to this message:
 Message 33 by nwr, posted 11-06-2006 12:54 PM Son Goku has replied

  
Son Goku
Inactive Member


Message 35 of 100 (362167)
11-06-2006 1:32 PM
Reply to: Message 33 by nwr
11-06-2006 12:54 PM


Re: Back to the drawing board
nwr writes:
The evidence that the cosmos is expanding, however, is far from satisfying.
I see, it is the expansion itself, rather than conclusions drawn from expansion, that you think isn't well enough supported. Like Percy, I think it would be good to hear an exposition on flaws in current scientific theories.
Maybe not so much based around the evidence, but more so why this particular theory wouldn't reach your/ones acceptance quota.

This message is a reply to:
 Message 33 by nwr, posted 11-06-2006 12:54 PM nwr has seen this message but not replied

  
Son Goku
Inactive Member


Message 37 of 100 (362350)
11-07-2006 5:59 AM
Reply to: Message 36 by nwr
11-06-2006 11:01 PM


Very Good
Let me first note that I have other things to do with my life than read the latest astronomy journals. So it is always possible that there is evidence out there that could convince me, but I haven't seen it.
Don't worry, I think demanding you put that much effort into a forum post would be a bit unfair.
Anyway....
It could be that there is something we don't fully understand about electromagnetic waves, that explains the redshift. I'll note that the possibility has been considered and is usually referred to, somewhat disparagingly, as a tired light theory.
I don't take any particular issue with anything you wrote, but I'll just give a little exposition on this quote.
Electromagnetism is probably the best understood of the four forces, as the Quantum Mechanical theory describing it (Quantum Electrodynamics) is confirmed more than any other theory in science.
This doesn't really change your criticism, instead I would say that anything unknown with regard to redshift would be more likely to come from some interaction electromagnetic waves have with "X" (whatever X is) on their way to Earth, rather than something misunderstood about the waves themselves.
However this is a minor point.
Edited by Son Goku, : Slight spelling correction.

This message is a reply to:
 Message 36 by nwr, posted 11-06-2006 11:01 PM nwr has seen this message but not replied

Replies to this message:
 Message 39 by cavediver, posted 11-07-2006 6:24 AM Son Goku has replied

  
Son Goku
Inactive Member


Message 46 of 100 (362467)
11-07-2006 5:04 PM
Reply to: Message 45 by nwr
11-07-2006 3:26 PM


The Singularity
Just to mention the singularity of most finite-past models of the universe is an artefact of GR, but usually isn't included in the Big Bang model.
This is to do with all our physical models based around fields being what we call effective theories. This is a far more prominent term in particle theory when used to discuss the quantum fields particle physics uses, however it also used by cosmologists to refer to classical GR.
Basically the theory is only taken to hold up to certain energies/distances with the higher level predications of the theory being literally cut off.
So the Big Bang works with this universe:
as opposed to:
The state of matter at the point were the cone gets truncated is modelled as a quark-gluon plasma along with a lepton plasma. The "real" Big Bang theory would be this quark-gluon and lepton plasmas living on a truncated cone model.
It starts by solving the GR field equations for an expanding universe, which gives you a universe with a singularity and cutting off the solution at a point in time when GR is a well defined theory and particle physics works according to the standard model. It then puts the plasmas of particles on the spacetime at this truncation point and using sensible initial conditions for the plasmas lets them evolve, giving predictions for observations today, thereby cutting off what we know to be a dubious extrapolation.

This message is a reply to:
 Message 45 by nwr, posted 11-07-2006 3:26 PM nwr has seen this message but not replied

  
Son Goku
Inactive Member


Message 48 of 100 (362490)
11-07-2006 6:39 PM
Reply to: Message 39 by cavediver
11-07-2006 6:24 AM


Long time, no see.
Hey, SG! Been a while... working on anything suitably on-topic for this thread?
Unfortunately what I am working on (and will be working on much more next year) is always just slightly outside the scope of these threads. Kind of related to cosmology, but cosmological discussions never really need it.

This message is a reply to:
 Message 39 by cavediver, posted 11-07-2006 6:24 AM cavediver has not replied

  
Son Goku
Inactive Member


Message 51 of 100 (362548)
11-08-2006 3:11 AM
Reply to: Message 50 by nwr
11-07-2006 11:06 PM


Re: BB skepticism
The conventional wisdom says that we should use the photon theory of light rather than the wave theory. So where does that leave the theoretical derivation?
The average amplitude(energy) of light in the universe is far to high to require QED, so Maxwell's theory is sufficient. Even if you use QED you pretty much get things scattering into the width of the classical beam anyway, so it makes no difference.

This message is a reply to:
 Message 50 by nwr, posted 11-07-2006 11:06 PM nwr has seen this message but not replied

  
Son Goku
Inactive Member


Message 56 of 100 (362715)
11-08-2006 7:56 PM
Reply to: Message 55 by nwr
11-08-2006 6:07 PM


Metaphysical claims
Perhaps to aid the discussion, what scientific theories do you see as having well justified metaphysical claims?
Also a small side question, what metaphysical claims of QM do you not accept? Is it just the existence of certain particles or is it other claims as well?
Do you only consider certain particles to be questionable, i.e. quarks are, but not electrons.
I think both these questions are important to see how you view any given physical theory.
Edited by Son Goku, : Grammar and spelling.

This message is a reply to:
 Message 55 by nwr, posted 11-08-2006 6:07 PM nwr has replied

Replies to this message:
 Message 57 by nwr, posted 11-08-2006 8:53 PM Son Goku has not replied

  
Son Goku
Inactive Member


Message 60 of 100 (362789)
11-09-2006 3:50 AM
Reply to: Message 59 by nwr
11-08-2006 11:25 PM


To invert the waters,.....
To muddy the waters, I have no problem with the metaphysical claims of Newtonian mechanics.
Funny, because as time has progressed, I have come to see momentum and force as useful fictions and come to see electrons, quarks and black holes as more real.
Anyway, I see you have strict requirements on justifying metaphysical claims. The fact that you extend this to the everyday is a good thing, as I think people are too harsh on things like electrons without being equally harsh on certain everyday concepts.
So let's take the epistemic road, how decent a theory is the big bang in this regard?
Would I be correct in saying you don't believe it is unique enough?
(i.e., that too many of its predictions and gross features can be replicated by other theories)

This message is a reply to:
 Message 59 by nwr, posted 11-08-2006 11:25 PM nwr has replied

Replies to this message:
 Message 64 by nwr, posted 11-09-2006 12:26 PM Son Goku has not replied

  
Son Goku
Inactive Member


Message 68 of 100 (363036)
11-10-2006 8:38 AM
Reply to: Message 66 by cavediver
11-09-2006 2:56 PM


Off topic
Whatever you can construct to give GR both locally and Galactically, whilst providing for a static universe with some strange unknown red-shift phenomenon will be some strange bastard of a theory
For your interest have you heard the "Island in theory space" discussion about QM that has appeared in the last year?
No webpage found at provided URL: http://www.scottaaronson.com/papers/island.pdf

This message is a reply to:
 Message 66 by cavediver, posted 11-09-2006 2:56 PM cavediver has replied

Replies to this message:
 Message 69 by cavediver, posted 11-10-2006 8:54 AM Son Goku has not replied

  
Son Goku
Inactive Member


Message 77 of 100 (364846)
11-20-2006 7:46 AM
Reply to: Message 75 by nwr
11-19-2006 10:27 AM


Aether and gravity
A scientific theory brings with it empirical methodology, which may include methods for making testable predictions. It also brings an explanation. My skepticism is only toward the explanation component. For maybe 200 years, the luminiferous ether was the accepted explanation for light. This had been thoroughly tested, and was better confirmed that BB cosmology. Yet we have now rejected the luminiferous ether as non-existent and part of a flawed explanation. Newton's theory of gravity reigned supreme for even longer, and was more thoroughly confirmed. Yet we have rejected the Newtonian explanation in favor of GR. In both cases (the ether, and Newtonian gravitation) we continue to use much of the empirical methodology, but we no longer accept the explanations.
This might be slightly off topic, but there are a few very big differences between the Aether and Newton's gravity. For instance the aether was never experimentally verified, to my knowledge. In fact it was never really tested until Mitchelson and Morely.
Secondly the luminiferous aether was never thought to be definitively correct by most physicists, it was simply considered as the most likely way to come to terms with Maxwell's equations.
Before this statements about the aether were confined to very vague one offs like "Maybe light is some kind of disturbance in some kind of medium".
As for the "truth" of Newton's gravity, I work with what you might call a notion of appropriate truth or "truth on that level". However that discussion is probably best kept for another thread.

This message is a reply to:
 Message 75 by nwr, posted 11-19-2006 10:27 AM nwr has replied

Replies to this message:
 Message 79 by nwr, posted 11-20-2006 6:03 PM Son Goku has replied

  
Son Goku
Inactive Member


Message 81 of 100 (365000)
11-20-2006 7:10 PM
Reply to: Message 79 by nwr
11-20-2006 6:03 PM


Re: Aether and gravity
That's not a difference. That's a similarity. The claimed recessional velocities (measured as rate of change of distance) of distant galaxies has never been experimentally verified.
I was only talking about differences between the aether and Newton's gravity. Differences between the aether and the Big Bang theory would be harder to assess, for me personally, because one is a dynamic research system where as the other was a fairly static idea.
There seems to be something wrong about that. The idea of aether waves apparently goes back to Christiaan Huygens. Maxwell's equations began the downfall of the ether, for they suggested you could have waves without a medium.
That's what I'm saying. The aether was confined to a few one off sentences by the great physicists of the pre-Boltzmann era. There was no real working theory of light in which to quantify those kind of statements about light, all that was really definitive was stuff like Snell's law. However it was Maxwell's contradiction of the medium notion in general that really stirred up the idea, hence leading to Mitchelson and Morely testing it.
Edited by Son Goku, : Yikes, assess not asses!
Edited by Son Goku, : Minor correction

This message is a reply to:
 Message 79 by nwr, posted 11-20-2006 6:03 PM nwr has replied

Replies to this message:
 Message 83 by Michael, posted 11-20-2006 7:37 PM Son Goku has not replied
 Message 87 by nwr, posted 11-20-2006 9:05 PM Son Goku has not replied

  
Son Goku
Inactive Member


Message 90 of 100 (365116)
11-21-2006 9:28 AM


WMAP
Michael writes:
Apologies for the pedantry, but I believe you mean Michelson and Morley.
Cheers.
I always make that mistake, thanks for the correction.
nwr writes:
Okay, I missed that, probably because I was not trying to suggest they were similar. I was simply providing two examples where we have since rejected what was accepted explanation, though we continue to use much of the associated empirical methodology.
To be fair it was an off-topic comment on my part, so it doesn't really effect your main argument.
Anyway perhaps a good general piece of evidence for the expansion is the WMAP in general (as has already been said) and some of its fallout analysis such as:
A paper going into some observational details.
Might be good to see how the experimental side works.
A paper on what the WMAP mean for expansion theories.
Basically puts a constraint on certain models.
I apologize that I can't get any non-technical references, although the first paper isn’t too bad.
Edited by Son Goku, : Tag correction.

Replies to this message:
 Message 91 by baloneydetector#zero, posted 11-21-2006 11:39 AM Son Goku has replied

  
Son Goku
Inactive Member


Message 94 of 100 (365340)
11-22-2006 9:01 AM
Reply to: Message 91 by baloneydetector#zero
11-21-2006 11:39 AM


Re: Great Debates
But, to be perfectly frank, I'm still quite happy with most of the thoughts of my initial thread.
Unfortunately there is a few incorrect statements in your original post.
A general tendency of criticisms about the Big Bang is to state that red-shift itself isn't enough to confirm Cosmological expansion because it could be due to other unforeseen causes.
However it isn't Red-Shift itself that is taken as evidence, but the relation of the red-shift to the distance of the galaxies is exactly the ratio as predicted by the Friedman solution to the Einsteinian Field Equations.
To be more accurate S, the distance to the object we are looking at, is a function of (dv/v), the fractional red-shift, in the following manner:
S = c/H(dv/v) where c = speed of light and H = Hubble's constant.
Which is a linear relation.
Not only does this relation hold for objects near us, but the deviation from this relation also holds when you look far enough.
The deviation being the non-linear curve being introduced.
Deviations from this term come from , which is a measurement of the expansion of the universe. So the expansion of the universe predicts the qudratic and eventually cubic terms in the diagram above.
Other methods would have difficulty replicating this.
Edited by Son Goku, : Slight Correction.

This message is a reply to:
 Message 91 by baloneydetector#zero, posted 11-21-2006 11:39 AM baloneydetector#zero has replied

Replies to this message:
 Message 96 by baloneydetector#zero, posted 11-22-2006 12:52 PM Son Goku has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024