...and then test those "guesses" to determine which ones are correct, so as to build upon the technological knowledge of the human race which has brought us so far from our hunter-gatherer beginnings. Did you "forget" to mention that part?
[polemikos:] There are more theories than there are scientists. What's up with that?
Exaggerating the number of hypotheses doesn't help your case. As far as "what's up with that", science works by having people propose as many possible explanations as they can think of, and then testing them to see which ones best explain the evidence and correctly predict the results of additional experiments and/or the nature of further evidence. If none are entirely satisfactory then it's time for more "guessing" in search of the full answer.
[Erik Latranyi:] The above article conclusively proves that science know absolutely nothing about what causes anything. Once again.
If you think that "science know [sic] absolutely nothing" about things, perhaps it has something to do with how unclear you are about straightforward notions such as what constitutes "conclusively proving" something.
Read my prior post, it shows how there's a lot more knowledge regarding and support for the ideas in the paper under discussion than you apparently grasp.
Looking at the actual contents of the paper, we see a number of things that certain folks might find educational.
First, it very clearly labels its model as hypothesis. It specifically calls it a "hypothesis" four separate times. This is the technical word for "guess", basically, so this should forestall any accusations that the authors were trying to overstate their case, or were recklessly mistaking their "guesses" for established facts.
Second, this "guess" (proposed explanation for available evidence) wasn't just something they came up with at some late-night beer-fueled bull session at the local student union because it sounded "far out, man". Instead, they base it on a great deal of prior foundation in several fields (biology, paleontology, nuclear physics, astrophysics, geology, etc.) Perhaps you missed the two and a half pages of references.
In fact, the model itself (GRBs initiating mass extinctions), as they freely admit (by citing earlier works) is not new. It has already been established as a workable theory ("theory: a coherent group of general propositions used as principles of explanation for a class of phenomena") by prior research and verifications. Their own contribution in this paper is simply to apply that theory to a particular case (the Ordovician mass extinction) and see whether the GRB model well explains the features of that particular mass extinction, or not. They state their hypothesis explicitly: "We suggest that the late Ordovician extinction may have been initiated by a GRB."
Third, this is what's known as testing a model. That's how science separates the correct models from the incorrect ones. That's how it progresses beyond "knowing absolutely nothing" on a subject to knowing a great deal about it and increasing human knowledge. That's what makes it worth "Millions upon billions in grants" to pay scientists to engage in a complex undertaking which begins (but hardly ends) with making "guesses". Not that this particular one cost much money, they appear to have mostly spent their time digging up relevant prior papers and bringing together the relevant results to check out the details.
Fourth, the authors of this paper did a lot more than just go, "we're calling a press conference to say that gosh, who knows, maybe GRBs made the Earth cold or something and had something to do with an extinction or two". (In fact, no press conference was involved, they just published their paper and several outlets picked up on it.) They spent their time checking to see how well predictions of the GRB model lined up with known findings about the Ordovician extinction. First they worked out the expected theoretical results of a GRB:
1. "A strong burst of cosmic rays at the Earth would be expected only for isotropic GRB emission with a very hard spectrum. Thus, the instantaneous biotic effects of GRB will be moderate and confined to the facing side of the Earth."Fifth, they then compared the magnitudes and characteristics of those predicted results with the actual features of the Ordovician extinction:2. "Long-term effects of GRB would spread around the Earth and include ozone layer depletion, global cooling, acid rain, and radionuclide production."
3. "A GRB may have paradoxically produced darkened skies and heightened UV radiation. Modest increases in UV flux, particularly around 300 nm, can be lethal to a variety of organisms (Kiesecker et al., 2001; Hader et al., 2003), including the phytoplankton which are the basis for the marine food chain as well as oxygen production."
1. Species living in shallow water were more likely to go extinct than those dwelling in deeper water (UV light does not penetrate into deep water).Sixth, they outline one type of further investigation that could be done to confirm or disprove the hypothesis, so that further knowledge can be gained on this issue:2. There is a very strong correlation between the amount of time that a trilobite species spent in a planktonic larval stage and its chance of extinction in the Ordovician (UV affects small creatures more than large).
3. The Ordovician extinction is already known as a period of two alternating cooling/warming cycles, and cooling followed by warming would be expected from a GRB event.
4. Supernovae tend to occur in clusters, and the spacing of the two Ordovician cooling cycles is consistent with supernovae "chain" spacing.
5. The Ordovician was not a period where known causes of other cooling cycles or ice ages were in effect.
6. Other kinds of extinction-causing changes would have produced different patterns of extinction.
"This hypothesis suggests that a closer look be taken at the geographical distribution of extinctions in the late Ordovician along the line of what Anstey et al. (2003) have done. A strong initial muon burst might seriously irradiate only one side of the Earth to considerable ocean depth, while the other side would mostly be irradiated by post-burst solar UV due to ozone loss. This suggests an extinction pattern emphasizing depthdependent extinction predominantly in one hemisphere, with more complete extinction in the other hemisphere."Seventh, by publishing the paper they knowingly initiate the next stage which is always the purpose of scientific publishing: To invite additions from the rest of the scientific community concerning things the authors may have overlooked, possible contrary evidence or competing theories, confirming evidence from others who might have knowledge that seems to make more sense in light of the hypothesis, suggested action on what evidence might be specifically hunted for (or experiments performed) that would have the best chance of proving/disproving the hypothesis, etc.
The work on this hypothesis is not finished, of course, but then in a real sense no scientific model's work is ever done, and the authors clearly know this. Every author just adds the pieces of the scientific puzzle he can, and passes it on to the scientific community to see what else someone may be able to add. Over time the unworkable sections drop out, and the workable sections of the "big picture" get more and more detailed and begin to join each other to form even larger interrelated views of the entire puzzle of how the universe works and what has happened in it in the past.
This is how science is done. I don't think anyone in our technological age can argue with the results.