Is the cosmic microwave background from the Big Bang?

Donald Scott makes a remark about the greenhouse effect that is interesting. He points out, what in retrospect is pretty obvious, that a greenhouse really works by stopping heat escaping by convection!

If a greenhouse really worked as suggested, I think the glass panes would be hot - just as if the CO2 was having an appreciable effect, the troposphere would be warmed up - and that hasn't been detected. I think it is conceivable that referring to this phenomenon as the greenhouse effect, was a false analogy, which accidentally or deliberately exaggerated the effect - so those who say weak AGW might/should be real, might be right, but the effect doesn't resemble the operation of a greenhouse.

I got sick of Tom Findlay's book (fortunately I got the free PDF version), because he seemed to assume essentially no science knowledge on behalf of his readers. He was explaining things at a level that I knew at about age 10! I don't really know why people write books like that, because someone who never bothered to learn basic science, just isn't going to want to read a book about alternative cosmology!

However, the above Donald Scott's "Electric Sky", seems a much more interesting read. I must say, the EU (I wish it didn't have that acronym!) is a very thought-provoking concept. I'd really like EthanT to read it and tell us what he feels. I do feel a sympathy for those who feel mathematical abstraction has led cosmology astray. It is vividly apparent when people discuss a time 10^(-36) sec after the big bang! As Scott comments, in most areas of science (he is an electrical engineer) equations with singularities are recognised to be invalid at or near those points (I think EthanT said as much somewhere above).

BTW, We probably should not dwell on CAGW, or we will scare EthanT and others away, and the CAGW vultures will move in instead :) In any case, the nature of the universe is a much more interesting topic.

David

I agree to some extent about Findlay's book (got just over half-way waiting for it to start, then scanned the rest and decided to stop), and that Donald Scott's is better. But for the person with little scientific training, I can't see that there's anything much better out there. It's surprising: many who dropped science in school in favour of the arts can be surprisingly ignorant about the basics. Ask them to sign a petition against dihydrogen monoxide and they might well; ask them what the substrate of computer chips is, and they're quite likely to say silicone; and they're likely vague over the difference between carbon, carbon monoxide, carbon dioxide, carbonic acid, carbonates, and so on.
 
This seemed like the most fitting place for this. I always had a feeling these anomalies would go away as they perfected techniques for extracting out the foreground. Sorry Multiverse fans ;-)

Planck's Mystery Cosmic 'Cold Spot' May Be an Error

http://www.space.com/26772-planck-mystery-cold-spot-error.html?cmpid=514630_20140812_29592746

"Using new techniques to separate the foreground light from the background, and taking into account effects like the motion of our Galaxy, we found that most of the claimed anomalies we studied, like the cold spot, stop being problematic," said lead researcher Anaïs Rassat, of the Ecole Polytechnique Fédérale de Lausanne, Switzerland.

Although this study appears to have corrected for previously overlooked effects in Planck observations, some anomalies remain in the data, leaving room for some of the more exotic hypotheses about the origin and nature of our universe. But as for Planck's "cold spot," that mystery might be down to observational error and not something real.
 
Maybe relevant:

The Black Hole at the Beginning of Time --"We may have Emerged from a Black Hole in a Higher-Dimensional Universe"

In their proposed scenario, our universe was never inside the singularity; rather, it came into being outside an event horizon, protected from the singularity. It originated as – and remains – just one feature in the imploded wreck of a four-dimensional star.

The researchers emphasize that this idea, though it may sound “absurd,” is grounded firmly in the best modern mathematics describing space and time. Specifically, they’ve used the tools of holography to “turn the big bang into a cosmic mirage.” Along the way, their model appears to address long-standing cosmological puzzles and – crucially – produce testable predictions.

Of course, our intuition tends to recoil at the idea that everything and everyone we know emerged from the event horizon of a single four-dimensional black hole. We have no concept of what a four-dimensional universe might look like. We don’t know how a four-dimensional “parent” universe itself came to be.

But our fallible human intuitions, the researchers argue, evolved in a three-dimensional world that may only reveal shadows of reality.

They draw a parallel to Plato’s allegory of the cave, in which prisoners spend their lives seeing only the flickering shadows cast by a fire on a cavern wall.

“Their shackles have prevented them from perceiving the true world, a realm with one additional dimension,” they write. “Plato’s prisoners didn’t understand the powers behind the sun, just as we don’t understand the four-dimensional bulk universe. But at least they knew where to look for answers.”
 
I mentioned earler in this thread how there has been a lot of reseach into alternative theories of gravity - called modified gravity, or MG, apparently these days. Anyhow, looks like they found a way to test this.

New test may provide 'smoking gun' for modified gravity

(Phys.org) —Since 1916, general relativity has provided a description of gravity that can explain many observations, including objects in free fall, gravitational lensing by massive objects, and black holes. Despite the success of the theory for nearly 100 years, scientists have been looking at ways to modify general relativity in order for it to better explain certain observations—particularly the accelerated expansion of the universe. Although these modifications can be very different from one another, they generally fall into the category of "modified gravity."

Like any scientific prediction, modified gravity must be experimentally tested in order for scientists to confirm its validity. Although significant progress has been achieved in recent years in designing observational tests of gravity's effects in the universe that might reveal the presence of modified gravity, there is still no conclusive evidence for its existence.

Now in a new paper published in Physical Review Letters, Wojciech A. Hellwing, et al., have proposed a new test of modified gravity that is based on measuring the tendency of well-separated galaxies to approach each other. This movement is called the galaxy pairwise velocity.

The physicists show that the galaxy pairwise velocity distribution of many galaxies with a wide range of masses is expected to deviate from the predictions of general relativity by significant amounts: between 5 and 10 standard deviations or higher, depending on the model. Due to these large deviations, this proposed test could potentially offer the strongest evidence in support of modified gravity to date.


"Modified gravity (MG) theories have gained a lot of attention in the last decade," Hellwing, a researcher at Durham University in the UK and the University of Warsaw in Poland, told Phys.org. "Mostly because this class of theories provides an alternative explanation of the late-time accelerated expansion of the universe, while avoiding some conceptual problems related to the classical general relativity (GR) picture in which Einstein's cosmological constant is supposed to drive this acceleration. In the classical GR picture, one needs to have a very small value of the cosmological constant, which is hard to reconcile with quantum field theory. MG theories provide an alternative explanation, but in most of these theories modifications to gravity not only can account for accelerated expansion but also can produce non-negligible enhancement to gravity at cosmic scales relevant to galaxy formation and dynamics. Therefore it is of utmost importance to find observational evidence that could distinguish between these two scenarios (GR or MG)."
 
Back
Top