It's not a ridiculous claim, if they're talking about the observable universe. We can't see every galaxy, but there's no reason to believe that what we are seeing is not a representative sample. It's harder to study the very earliest galaxies, because they're the farthest away and therefore faintest, but we can see galaxies all the way back to when galaxies probably first formed, and we can see things even earlier than that (e.g., the cosmic background radiation).
Gravitational waves will be quite negligible compared to the total mass energy of the galaxies (though they will be a significant fraction of the mass-energy of the central black holes). Greater mass loss will be due simply to stars being ejected from the galaxies during the collision, but the end result will still be pretty close to the original mass of the system.
Now, when someone can show me some live footage of two stars crashing into each other and a really big explosion, then I'll be impressed. That's exactly what some gamma ray bursts are thought to be: colliding stars. However, since they're colliding neutron stars, we can't really see them before the explosion, so all you see is a great big flash at the end. You don't see two stars zooming toward each other before they collide.
So this leads me to wonder, will a merger of this size cause a larger gravitational force as 4 swirling masses converge. Not really. There will be more mass concentrated in the center of wherever the final galaxy ends up, but the gravitational field outside the boundary of where the current galaxies are won't really change.
Would this draw other galaxies closer to the newly merged one, ever increasing the size of the merged one? No more so than the current galaxies are doing now; the final galaxy will have more or less the same mass as the originals, after all.
If galaxies are close enough, they can collide. Generally, a gravitationally bound system will resist the Hubble expansion (which is why our solar system and galaxy are not expanding at the rate the universe does). Only when the bodies are spread far apart and not gravitationally bound to each other does the universe's expansion dominate. See this FAQ and this and this for details.
The astronomer quoted in that link has specifically stated that his work was misrepresented; see here and here. The Sun's orbit in the galaxy indicates that it did indeed originate in the Milky Way.
Maybe he meant that there is a different "evil color" for each person, so you have to run through the whole range to make sure everyone's own color is covered.
Even disregarding your enormous sample size of 3, did you ever consider an alternative hypothesis that ex-military, self-taught IT, or MBA managers might have been the problem? How many of your good male managers have been ex-military, self-taught IT, or MBAs?
The rest of your argument just boils down to "I am unable to relate to women" which only says something about you personally, not about their ability as IT managers.
Anyone taking honours-level mathematics will author thousands of proofs before they graduate.
By "author" they mean... "author". As in writing it up and getting it published, in a peer reviewed academic journal. See here, published in Journal of Physics A: Mathematical and General.
More cosmic ray -> more mutation -> higher bio-diversity?
No, they find that more cosmic rays are associated with lower biodiversity.
I don't know about you but I don't think this is science. This is "making up sensible stories and publish in Nature".
Uh, that's exactly how science starts out, as "sensible stories": someone comes up with an interesting hypothesis, finds that there is evidence consistent with it, and puts it out there. The idea doesn't have to be airtight to be scientific, novel, or important. (And they weren't published in Nature, but rather in Astrophysical Journal. The 2005 Nature paper merely reported the existence of the 62-million year biodiversity cycle.)
We need to clean up science... starting with the abuses of statistics...
Please, tell me how the authors have "abused statistics".
This theory is not intended to explain the large, irregular, rapid mass extinctions, but rather smaller, regular, gradual biodiversity changes. And the 62 million year cycle that they're trying to explain has not been known for decades; it was only discovered two years ago.
You are correct in that in order to get 62my ago, you have to fudge quite a bit. [...] Sounds like someone needed to "publish or perish" for this article. You seem very casual about making quasi-libelous statements, but the reality is that, despite the Slashdot headlines, this theory is not intended to explain the mass extinction events to which you are referring. Rather, as other posters have pointed out, it has to do with smaller, periodic patterns in biodiversity.
Ok, you're right, I neglected the difference between the two. Yes, equatorial and polar geostationary orbits should have different daylight percentages.
That's a good point. People often neglect the importance of aerosols in cooling. Projections and policy depend on all the forcings, positive and negative, not just the positive forcings from greenhouse gases.
Mars is heating at a similar rate to the earth right now, and I doubt a couple of rovers and some crashed stuff is causing that. I don't remember at what rate Mars has warmed, but if it's really the same rate as Earth, that's evidence against the warming trends having a common cause. The transient temperature response on Earth is dominated by ocean heat uptake and other factors which are nonexistent on Mars; the two planets should have very different transient responses (meaning decadal-scale) to external forcings (not to mention the different amounts of sunlight they receive!).
Maybe, perhaps, possibly, the sun is getting hotter too? Neither the late 20th century Earth warming nor the recent Martian warming agree well in magnitude, rate, or timing with measured changes in solar irradiance. Note too the measured trends in Martian albedo during the warming period.
For that matter, if you're so willing to place so much importance on our relatively scant knowledge of Martian climate, why are you so dismissive of our much greater knowledge of the Earth's climate and its drivers?
Is the earth getting warmer because of a temporally local phenomenon or is this part of a longer-timed cycle? There is no evidence of any such cycle, nor is there any evidence of any actual forcings which could be producing such a cycle at this time. Cycles have to be caused by something, you know: periodic changes in solar irradiance, volcanism, orbital parameters, etc. No cycles have been identified which are capable of accounting for the observed warming. You can't just wave your hands and say "a cycle could be due". By contrast, greenhouse gas-induced warming agrees with the actual observed warming. Moreover, GHG warming has implications such as polar amplification, stratospheric cooling, and so on, which have been observed, and are different from the implications of other sources of warming.
You also keep pretending that we only have 30 years worth of useful data, which is far from the case.
OK, tell me what the weather's going to be outside tomorrow based on what the weather is right...NOW. That is not even remotely a valid comparison. More accurate would be, say, predicting the weather over the next few days based on today's weather data, but even then there are obvious differences.
Extrapolate 100 years in the future off of 30 years of reliable global data. You have a funny definition of "reliable". The instrumental record extends back to the 19th century and, while not as accurate as modern data, is accurate enough to detect trends.
You've read the rebuttals and surely came to the same conclusion I did: No, I didn't.
These guys did it for grants. This, of course, is nonsense. You get a grant for what question you're going to investigate, not for what pre-determined result you say you're going to arrive at. Your findings are reported after you have the money.
And recent studies in Iceland show that the there used to be deciduous forests there. So?
Studies from pre-industrial economics show that farm output increased, likely leading to the industrial revolution, because the growing seasons were slightly longer and the weather was warmer. If you're referring to the world's emergence from the Little Ice Age, I don't doubt that was beneficial to the European powers who kicked off the Industrial Revolution. But, again, your point escapes me. If you're trying to argue that period of time was warmer than it is now, such a conclusion is not supported by the evidence. If you're trying to argue that warming is beneficial, you're begging the question.
It's been warmer in the past. It's been colder. This is well known. Again, what is your point?
How many would it take to get a physical threat before some of them decided that their wife and kids were pretty important, they liked living and maybe, just maybe, it wasn't worth it to publish, and that they should start researching microclimatology. I happen to know a number of environmental scientists, some of whom study global climate, and physical threats to their life are not even on their radar. I can't imagine that this is a prevalent concern. Even the ones who probably have received threats (like Mann) are still working in the field.
M&M comes to mind. Many peer reviewed journals are refusing to publish any work that doesn't toe their line. Really? Then where do all the skeptical papers being hyped from the other side of the spectrum come from? Nearly all of the prominent skeptics have published in peer reviewed journals. Which peer reviewed journal has refused to publish "any work that doesn't toe their line" (whatever that line is supposed to be)?
I will argue that we cannot make accurate climate predictions (at least within the range that is relevant to the anthroprogenic global warming debate) because we have utterly failed to do so in the past. Really? Hansen's climate projections from 1990 still hold up pretty well (especially considering the relative crudity of the models back then), although he somewhat underestimated the sea level rise.
That data that the IPCC use show no warming after 1999, That's certainly not true. All the years after 1999 are warmer than 1999 (see Figure SPM.3 in the IPCC report). Actually, it's not really correct to pick a specific year and measure everything relative to that; to look at trends you want to look at a 5- or 10-year moving average, and that too shows warming after 1999.
which doesn't even fit the past of the model, let alone the future I can't even parse that sentence. The post-1999 temperatures are supposed to fit both the past and future of the model? Which one is it? In any case, the IPCC model projections of post-1999 temperatures are consistent with what actually happened, within the range of natural interannual variability.
I think really what the whole problem is with the debate is that there's a huge difference between the approaches of the typical person and the scientist to uncertainty. Well, I think that is certainly a big contributor. Witness all the misguided demands for "proof" of global warming.
Off the top of my head, I would assume it would depend on what point on earth the satellite is synchronous to... Which point it's synchronous to will determine at what time it's in darkness. But it shouldn't have much to do with the average amount of time it's in darkness, over the span of a year as the Earth travels around the Sun.
Slashdot Mirror
That's technically true, due to mass loss from ejection, but the overall mass is still going to be pretty much the same, which was my overall point.
It's not a ridiculous claim, if they're talking about the observable universe. We can't see every galaxy, but there's no reason to believe that what we are seeing is not a representative sample. It's harder to study the very earliest galaxies, because they're the farthest away and therefore faintest, but we can see galaxies all the way back to when galaxies probably first formed, and we can see things even earlier than that (e.g., the cosmic background radiation).
Gravitational waves will be quite negligible compared to the total mass energy of the galaxies (though they will be a significant fraction of the mass-energy of the central black holes). Greater mass loss will be due simply to stars being ejected from the galaxies during the collision, but the end result will still be pretty close to the original mass of the system.
If galaxies are close enough, they can collide. Generally, a gravitationally bound system will resist the Hubble expansion (which is why our solar system and galaxy are not expanding at the rate the universe does). Only when the bodies are spread far apart and not gravitationally bound to each other does the universe's expansion dominate. See this FAQ and this and this for details.
The astronomer quoted in that link has specifically stated that his work was misrepresented; see here and here. The Sun's orbit in the galaxy indicates that it did indeed originate in the Milky Way.
Yes, there can be a largest galaxy in an infinite universe, but the probability that these particular galaxies will be it, is infinitesimally small.
No, it's just assumed that we're talking about the observable (or more likely, observed) universe.
Maybe he meant that there is a different "evil color" for each person, so you have to run through the whole range to make sure everyone's own color is covered.
Even disregarding your enormous sample size of 3, did you ever consider an alternative hypothesis that ex-military, self-taught IT, or MBA managers might have been the problem? How many of your good male managers have been ex-military, self-taught IT, or MBAs?
The rest of your argument just boils down to "I am unable to relate to women" which only says something about you personally, not about their ability as IT managers.
Anyone taking honours-level mathematics will author thousands of proofs before they graduate.
... "author". As in writing it up and getting it published, in a peer reviewed academic journal. See here, published in Journal of Physics A: Mathematical and General.
By "author" they mean
On statistical physics, Percolation and Gibbs states multiplicity for ferromagnetic Ashkin-Teller models on Z^2.
More cosmic ray -> more mutation -> higher bio-diversity?
No, they find that more cosmic rays are associated with lower biodiversity.
I don't know about you but I don't think this is science. This is "making up sensible stories and publish in Nature".
Uh, that's exactly how science starts out, as "sensible stories": someone comes up with an interesting hypothesis, finds that there is evidence consistent with it, and puts it out there. The idea doesn't have to be airtight to be scientific, novel, or important. (And they weren't published in Nature, but rather in Astrophysical Journal. The 2005 Nature paper merely reported the existence of the 62-million year biodiversity cycle.)
We need to clean up science... starting with the abuses of statistics...
Please, tell me how the authors have "abused statistics".
This theory is not intended to explain the large, irregular, rapid mass extinctions, but rather smaller, regular, gradual biodiversity changes. And the 62 million year cycle that they're trying to explain has not been known for decades; it was only discovered two years ago.
Ok, you're right, I neglected the difference between the two. Yes, equatorial and polar geostationary orbits should have different daylight percentages.
That's a good point. People often neglect the importance of aerosols in cooling. Projections and policy depend on all the forcings, positive and negative, not just the positive forcings from greenhouse gases.
For that matter, if you're so willing to place so much importance on our relatively scant knowledge of Martian climate, why are you so dismissive of our much greater knowledge of the Earth's climate and its drivers? Is the earth getting warmer because of a temporally local phenomenon or is this part of a longer-timed cycle? There is no evidence of any such cycle, nor is there any evidence of any actual forcings which could be producing such a cycle at this time. Cycles have to be caused by something, you know: periodic changes in solar irradiance, volcanism, orbital parameters, etc. No cycles have been identified which are capable of accounting for the observed warming. You can't just wave your hands and say "a cycle could be due". By contrast, greenhouse gas-induced warming agrees with the actual observed warming. Moreover, GHG warming has implications such as polar amplification, stratospheric cooling, and so on, which have been observed, and are different from the implications of other sources of warming.
You also keep pretending that we only have 30 years worth of useful data, which is far from the case.
Yes, that would matter (as would the size of the orbit and other factors); I was only speaking of a geosynchronous orbit.