"Universe's Energetic Cosmic Fog Stumps Scientists"

This is from the Fermi Gamma Ray telescope.

"Active galaxies can explain less than 30 percent of the extragalactic gamma-ray background Fermi sees," Ajello said. "That leaves a lot of room for scientific discovery as we puzzle out what else may be responsible."

Dark matter named as a usual possible culprit.

Better telescopes are just making the universe stranger so far. Still looking forward to the Webb to get some of the more extraordinarily redshifted optical sources.

Whats the "webb"?

dark matter is a cop out. Until you can show me some, it's just another way of saying "I have no idea", which would be the honest answer.

Lyndon said:

Whats the "webb"?

It's the James Webb telescope, designed with an eye to seeing in the infrared, so it should be able to tell us a bit more about high-redshift objects, I surmise. Finding objects at z=12 with already-evolved spectra would just make me giggle myself silly :)

Ed said:

dark matter is a cop out. Until you can show me some, it's just another way of saying "I have no idea", which would be the honest answer.

Pretty much :) Can't blame them too much, mind you. They have a class of phenomena that they cannot figure out, and they're understandably unwilling to put the universality of our current understanding of gravity itself on the chopping block. They're mining extensions to the standard model pretty hard, often mucking about in string theory for some ideas. I've even seen extra force proposals. Hawking has 'shadow branes' with gravity that can cross the branes back and forth.

So many of the proposals cannot be easily sorted from one another, either.

I wouldn't want to be an astrophysicist these days - that would be just too much inner brain time with no-to-little way to know whether you were right!

The problem is, that to get ahead and make a name for yourself in the field, you have to demonstrate a complete understanding of already accepted models, whether new data supports them or not. In fact, to really make a name for yourself, you develop some new math or create new entities in your mind with whatever properties they need to have to make inconvenient data fit the preconceived notions. Re-examining the premise is forbidden.

Personally, I subscribe to Occam's Razor. The simplest explanation is that the universe isn't really the universe. There are things outside of it exerting forces upon it that account for many of the mysterious things that are not yet understood. Also, there is no basis for a "smallest possible particle or entity". Mathematicians should be on board with this since, in theory, there's no point at which you have to stop halving anything, no matter how small you go.

Our brains don't like infinity and infinity doesn't care.

Re-examining the premise is forbidden.

It's not all premises, but some just seem to "stick". Cosmology is only in very small part an experimental science - it is in very large part a historical science but without the benefit of being able to put your hands on the artifacts in question. You ought to be able to make predictions even with a historical science (palaeontology can, for example), but cosmology seems to be much more often surprised than it should be. It gets really hard to correct sometimes.

What amazes me is how long some of these things have been going on. The bifurcation of what redshift meant in the 1930s is still going on today.

They seem to need at least a semi-completed framework to start on, which is aggravating in a way because when people acquiesce and come up with a more encompassing hypothesis (e.g. variable mass hypotheses), then they can wave away the discrepant data by waving away pieces in the encompassing hypothesis. That in itself is maddening.

The simplest explanation is that the universe isn't really the universe. There are things outside of it exerting forces upon it that account for many of the mysterious things that are not yet understood.

I used to figure that too, in a way. In part because I thought, based on the literature of the time, that the universe was a hypersphere - gravity would just been pulling everything towards the middle of that hypersphere, or the hypersphere would be expanding outwards, and matter dragged a bit, creating gravity wells.

These days, however, the experiments to test for some amount of non-Euclidian geometry have been done, and our universe is flat, dead flat, to about one in 10²⁰. That popped a lot of my bubbles.

Inflationary 'theory' still tries to rescue the hypersphere concept by inflating the universe far above and beyond the speed of light for a time.

Also to note: the 'Things outside of our universe exerting forces upon it' is not a particularly small set of possibilities :)

Also, there is no basis for a "smallest possible particle or entity"

Out of the many modern-day failures of physics, quantum theory is not one of them. It's counterintuitive and annoying, but you can run the math, run the real-life experiment, and it will work. It also rescues real life from the Ultraviolet Catastrophe.

One of the things that freaks me out in quantum physics is the equality QP - PQ = ih/2π. That is, if you multiply out momentum by position, and then multiply out position by momentum, the difference will not be zero. It's small, really small, but it's not zero.

Mathematicians should be on board with this since, in theory, there's no point at which you have to stop halving anything, no matter how small you go.

Relying on the math is how we've gotten ourselves into quite a few pickles already. General Relativity, for one, has gravity as geometry, and as such, is not quantized - its 'spacetime' is infinitely divisible. Getting this to account for measured quantum phenomena has tied up some of the greatest minds of the last decades. The three-decade-long foray into string theory is one of these.

Our brains don't like infinity and infinity doesn't care.

That has not typically been a limitation when it comes to physics :)

humor me for a minute. I'm a printer Jim, not a phsycisist!
anyway...to the layperson, the fact that the universe is flat would seem to suggest that either the "big bang" only took place in two dimensions, rather than an explosion that exerted force equally in all directions, or the medium within which the explosion took place was "softer" horizontally than vertically, which supposes that a medium existed.

on the QP - PQ thing, does that mean that the value of Q and/or P varies slightly depending on which is considered or observed first? If not, how do you make 3 x 2 not equal 2 x 3?

Generally speaking, the fractal nature of just about everything in the universe makes it seem unlikely to me that the universe we grew up in and are currently examining is the first and only. The variation on a theme nature of everything probably applies to our "Big Bang", just as it does to atoms, solar systems and galaxies.

I'm not going to come up with the theory of everything. One of you guys will probably do that, but the nearly century old "close but no cigar" situation seems to suggest it might be fruitful for cosmologists to ponder the ridiculous for a bit.

Ed said:

to the layperson, the fact that the universe is flat would seem to suggest that either the "big bang" only took place in two dimensions, rather than an explosion that exerted force equally in all directions

When they refer to the universe being "flat", they do not mean that it only took place in two dimensions, but rather it is our three dimensions that are flat in a fourth dimension - a fourth spatial dimension, not time-as-a-fourth dimension.

The idea behind closed universes in general, of which inflationary Big Bang is one variety, is that if you go far enough in one direction, you could theoretically come back to your original spot. You will have probably encountered the "balloon analogy" to Big Bang theory. The surface of the balloon is actually supposed to represent three dimensions, not two. We just don't happen to have hyperspherical (a sphere in four dimensions) balloons kicking around, so a lot of analogies squish one of the dimensions for effect, not unlike drawing a cube on a piece of paper or taking a picture.

That fourth dimensions is supposed to be what space expands "into" in a way, and it's also where Hawking's "shadow galaxies" would be... 'up' or 'down' in that fourth dimension.

I believe it is the WMAP data that astronomers have used to determine the flatness of the universe, though I do not know the details.

I think there would be - or ought to be - a great difficulty for current theory if the universe were actually flat, like it seems so very, very close to being. You cannot - correct me if I'm wrong - go from a closed universe to a flat universe without some magical giant scissors to break the wraparound. Inflationary theory says that the universe is closed (hyperspherical), but that space was so blown out during inflation that it looks really, really flat, like the earth seems flat to people standing on it, but many, many times more so.

Ed said:

on the QP - PQ thing, does that mean that the value of Q and/or P varies slightly depending on which is considered or observed first?

Yes, something like that. P and Q are matrices, though, not regular numbers, and they often do not commute (AB and BA do not have to be the same). Heisenberg discovered the relationship with Fourier analysis (a kind of spectral analysis - he based these on the transition states that they observed from atomic frequencies) back in 1925, and it appears to hold true. It is the basis of the "Heisenberg Uncertainty Principle" of which you may have heard.

Ed said:

One of you guys will probably do that, but the nearly century old "close but no cigar" situation seems to suggest it might be fruitful for cosmologists to ponder the ridiculous for a bit.

They really do need to shake it up a bit. This is a field that could stagnate for a long time otherwise.

Okay, if I'm imagining this right then the "flat" universe would be something like on onion. If you go "straight" along any plane, you would theoretically wind up back where you started eventually. Probably a bit more complicated than that since the "layers" would actually go in all directions. If you go out from the center, you're still traveling within a "layer".

A lot of the math that describes the universe doesn't jive with our normal perceptive ability, which leads me to suspect a deficiency in our genetic software. We're not always seeing what we think we're seeing. The math does its best to compensate, but something fundamental is missing.

An onion would imply multiple layers - we do not know if that is the case, though it might be. Trek's 'subspace' is along the lines of an onion model.

I'm not sure our perceptive ability is too bad when it comes to a lot of these models. A lot of things with 2D to 3D analogies really do work if you run the 3D to 4D math. Objects get 'leakier', for example, just the same as if you had a 2D being filled with 2D blood... add the third dimension and it would all drain out the sides in a second flat.

It can get pretty bad when it comes to String Theory space, though... what's a curled up dimension? How would that ever be perceived? How do Calabi-Yau spaces manifest themselves throughout space?

What we can't totally conceptualize, we have the math for. We're a lot more limited in evidence than conceptualization, IMO :)

and then there's the double slit experiment, where even a single photon and now I guess electron, neutron and even some larger buggers, display what's been described as a "probability pattern" on the screen. I understand we can't observe the photon as it travels without affecting its behavior, so we really don't know what happens between emission and arrival on the screen, but this implies that the photon itself doesn't "know" either, so it just covers all the bases by displaying the probabilities. Still sounds like a software compatibility issue to me.