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A Galactic glitch

by

Knud Jahnke and Rasmus Benestad

After having watched a new documentary called the ‘Cloud Mystery’ – and especially the bit about the galaxy (approximately 2 – 4 minutes into the linked video clip) – we realised that a very interesting point has been missed in earlier discussions about ‘climate, galactic cosmic rays and the evolution of the Milky Way galaxy.

It is claimed in ‘The Cloud Mystery’, the book ‘The Chilling Stars’, and related articles that our solar system takes about 250 million years to circle the Milky Way galaxy and that our solar system crosses one of the spiral arms about every ~150 million years (Shaviv 2003).

But is this true? Most likely not. As we will discuss below, this claim is seriously at odds with astrophysical data.

Here is a little background on the Milky Way: The arms of spiral galaxies are not constant entities in time. They are results of gravitational instabilities in the disk or are induced by external companions. These instabilities are moving mass ‘overdensities’ containing old stars and gas, but also newly formed stars recently created from local collapse of the overdense gas.

Arms move around a spiral galaxy with a pattern speed that is defined by the mass distribution. This pattern speed differs from the motion of individual stars, just like the speed of an ocean wave differs from the movement of water particles. Estimating the pattern speed is difficult, as it is not coupled to the motion of individual stars but can only be inferred indirectly. For this reason it has not yet been reliably measured for our Milky Way – unlike for some other spiral galaxies, for which our clear and unobstructed view from the outside allows an estimate.

So how did Shaviv come up with this number?

Measuring the rotational velocity of stars in the Milky Way disk or other spiral galaxies is straightforward. The rotation is not rigid, but depends on the encircled mass inside the orbit of a star, including the Dark Matter, a yet unknown but solidly established source of gravitational attraction. It is easy and a standard technique to measure rotation curves of galaxies as a function of radius, and this is also possible for the Milky Way.

The two different rotating velocities of arms and stars have a different radial dependence – to first order the arms get preserved as entities while the stars further out have much smaller angular velocities than stars further inside – so the relative velocity of a star with respect to the nearest spiral arm will depend on its distance from the centre of the galaxy. At a certain radius, the radius of co-rotation, the two velocities are identical and a star at this radius has zero relative velocity with respect to the spiral arm pattern. It stays “forever” in the same spiral arm – or outside of it.

What are the best estimates for the relative velocity of the Sun with respect to the spiral arm pattern of the Milky Way? As mentioned, the pattern speed of the spiral arm in the Milky Way has not been firmly established.

When investigating other spiral galaxies, however, it was found that almost independently of the wide range of possible assumptions on which the pattern speed estimate was based, the radius of co-rotation follows a simple law: rcorot=r0 * (3.0 +/- 0.5), where r0 is the scale length of the exponential disk of the galaxy (the surface brightness of spiral galaxies drops very close to exponentially from the center to the outside, setting a characteristic size scale). This was measured by Kranz et al. 2003.

Since the Milky Way is a completely normal spiral galaxy, we can apply this result to it. The scale length of the Milky Way disk has recent estimates ranging from 2.6 kilo-parsec (kpc, 1pc=3.3 light years) from the SDSS survey (Juric et al. 2008), through 2.8 kpc (Ohja 2001) to 3.5 kpc (Larsen & Humphreys 2003).

We also know the Sun’s distance to the galactic center well, 7.9 +/- 0.4 kpc (Eisenhauer et al. 2003), which means that the range of values for rcorot=9.1 +/- 1.9kpc. In other words, from this calculation the co-rotation radius of the Milky Way is between 7 and 11 kpc, and at 8 kpc our Sun is close to or at the radius of co-rotation. It almost certainly is not 6 kpc further inside, as Shaviv (2003) claims.

Shaviv (2003) lists in his Table 3 a number of values for the pattern speed of the spiral arms, taking from publications ranging from 1969 to 2001, two years before his article. In these papers the derived relative motion of the Sun relative to the arms ranges from Omegarel=+13.5 km/s/kpc to -4km/s/kpc, and includes estimates that are close to zero (-4km/s/kpc < than Omegarel < +7), i.e. a location near the radius of co-rotation in the majority of the publications, and most of the more recent ones. However, he selectively disregards most of these results.

If we add the above evidence that the radius of co-rotation lies at 9kpc distance and not further out, and convert this to relative velocities, e.g. by using the Milky Way rotation curve by Merrifield 1992, we obtain Omegarel =+3.2 km/s/kpc with an error range from -2.5 to +7.1km/s/kpc, and including zero. Shaviv’s derived “period for spiral arm crossing” of p=134 +/- 25Myr for four spiral arms is well outside the range derived from these values.

So it seems that Shaviv’s “periodicity” estimate for crossing of spiral arms by the sun does not hold up under scrutiny when using current astronomical results as the work by Kranz et al. This comes in addition to the previously shown fact that the correlation of cosmic ray flux with paleoclimatic data proposed by Shaviv and Veizer (2003) only arises “by making several arbitrary adjustments to the cosmic ray data” (Rahmstorf et al. 2004).

Note also that the question of current climate change is quite another matter from that over time scales of many millions of years – despite Shaviv’s remarkable press-release claims that “The operative significance of our research is that a significant reduction of the release of greenhouse gases will not significantly lower the global temperature”. As we repeatedly pointed out over the years: that global warming over the past decades is not linked to cosmic rays is clear from the fact that the cosmic ray measurements over the past 50 years do not show any trend (Schiermeier 2007).

Remarkably, the poor scientific basis of the galactic cosmic ray hypothesis seems to be inversely related to the amount of media backing it is getting. At least 3 documentaries (‘The Climate Conflict’, the ‘Global Warming Swindle’, and now ‘The Cloud Mystery‘) have been shown on television – all with a strong thrust of wanting to cast doubt on the human causes of global warming.

References:

Eisenhauer et al. 2003, ApJ, 597, 121; http://adsabs.harvard.edu/abs/2003ApJ…597L.121E

Kranz et al. 2003, ApJ, 586, 143; http://www.journals.uchicago.edu/doi/abs/10.1086/367551

Juric et al. 2008, ApJ, 673, 864; http://adsabs.harvard.edu/abs/2008ApJ…673..864J

Larsen & Humphreys 2003, AJ, 125,1958; http://adsabs.harvard.edu/abs/2003AJ….125.1958L

Merrifield 1992, AJ, 103, 1552; http://adsabs.harvard.edu/abs/1992AJ….103.1552M

Ohja 2001, MNRAS, 322, 426; http://adsabs.harvard.edu/abs/2001MNRAS.322..426O

Rahmstorf, S., et al., 2004: Cosmic rays, carbon dioxide and climate. Eos, 85(4), 38, 41.

Schiermeier, Q., No solar hiding place for greenhouse skeptics. Nature, 2007. 448: p. 8-9.

Shaviv, N., 2003, NewA, 8, 39; http://adsabs.harvard.edu/abs/2003NewA….8…39S

Shaviv, N. and J. Veizer, Celestial driver of Phanerozoic climate? GSA Today, 2003. 13(7): p. 4-10.

Reader Interactions

378 Responses to "A Galactic glitch"

  1. Hank, what is your point? I had read that cited article and it agrees that there was a warm bias due to the XBT’s.

    So are you agreeing that based on the observed “corrected” data that the oceans did not warm as much as earlier estimated? That most of the cooling was due to measuring biases so that there was only an insignificant decrease in OHC?

  2. Re: #40

    Gusbob,

    You’d certainly make Hannes AlfvÈn (and Eric Lerner and Halton Arp) happy with your comments about the “Electric Universe” but unfortunately you’d be lumped in with a whole new bunch of “Denialists”, the ones who claim the big bang never happened. They are even more vilified than the climate change denialists!

    Thanks guys for a great thread. If one of the purposes of this blog is to expose laymen to brilliant minds discussing a crucial issue and get them thinking critically, then I have to say you’ve succeeded.

    As Arnold said: I’ll be back!

  4. For that matter, read the link to the workshop. You’re asking for us to give you the answer they’re going to come up with — as though that would prove anything. Be patient. Read what they wrote:
    ———————
    Objective

    Analyses of concurrent XBT, CTD and Argo float observations indicate that there is a systematic difference in temperature profiles, which is likely due to an error in the XBT fall-rate equation. This error has introduced a warm bias in the global XBT data base. This workshop is dedicated to discuss the findings related to this issue by different groups. As a consequence, a new fall rate equation may need to be developed and applied to both past and future XBT data.
    ———————-

    This is how it’s done. This is the whole point about reading cites, following cites forward in time, and never assuming you know everything. The early work isn’t some kind of foundation that overturns everything if it’s adjusted. Work gets done like this all the time. Don’t get fixated on attacking yesterday’s papers.

  5. 296 Barton etc says: ‘We have good proxies which allow us to estimate it going back 400 years or so. Google “Judith Lean” or “Wang” + “Lean” for examples.’

    They can’t both be good as they disagree rather much.

  7. Leif Svalgaard writes:

    296 Barton etc says: ‘We have good proxies which allow us to estimate it going back 400 years or so. Google “Judith Lean” or “Wang” + “Lean” for examples.’

    They can’t both be good as they disagree rather much.

    Graph them and see if you still think so. They look like similar paths to me. And neither Lean 2000 nor Wange et al. 2005 show enough recent variation to cause the present global warming.

  8. Hank proffers “This is how it’s done. This is the whole point about reading cites, following cites forward in time, and never assuming you know everything. The early work isn’t some kind of foundation that overturns everything if it’s adjusted. Work gets done like this all the time. Don’t get fixated on attacking yesterday’s papers.”

    Hank, you repeatedly think you are telling me something I am unaware of. I am not the one who assumes they know everything, or assumes current paradigms will not change with new information. I simply argue a few points. The sun has greater consequence to environments than people here believe. I am completely happy and patient to watch the sun provide evidence of that as the solar/sunspot activity currently decreases and we can observe the effects on climate and how it may or may not overwhelm any CO2 effects.

    I also claim that the oceans because heat transfer happens virtually all at the surface, the oceans can store heat and release it on seasonal scales, decadal scales and most likely greater scales. Gavin suggested I get a red flag for suggesting such a thing but very simply ask where does that extra warmth come from during decadal El Nino events?

    And regards the XBT ocean instrumentation issues, you seem happy to offer patronizing answers, then offer a citation. And? Yet no matter how the instrumentation problems get resolved we are faced with an observational dilemma. Either there is less OHC and less of an oceanic warming trend than people previously proclaimed was needed to satisfy models because the XBT’s were warm-biased or we have a declining/static OHC which is also contrary to current CO2 based models. Actually it seems both problems exist because there seems to be no observational evidence that the oceans have been warming since 2003. But if you got a link and citation to such a measurement I’d love to see it. But I am patient. I will also wait to see a 2003-2013 trend analysis which I predict will show a decreasing OHC.

  9. Gusbob, you don’t even know enough about climate models to argue against them. Of course if the Sun’s output decreases, it will affect climate, and any climate model will reflect this variability. However, such solar variability persiste on a timescale of a few decades at most, while CO2 persists on a timescale of centuries to millennia. Bottom line: A couple of cooler years does not constitute a climate trend, and by any reasonable measure, global temperature remain high–as evidenced by the continued loss of glacial and sea ice.

  11. Hi Ray,

    [edit]

    First your current models don’t assume much solar variation when making predictions. And finally from what do you derive your solar variability estimates? The last 25 years? That’s solar weather, not solar climate. Second the loss of sea ice is only in the Arctic not the Antarctic. And if solar changes overwhelm CO2 effects, it points out that current models underestimated the attribution of warming by solar, and over estimated CO2. So your time scale of CO2 vs solar comment is of little value.

  13. Leif, can you give a pointer to the analysis and explanation that goes along with your chart?

  14. Re #305

    “296 Barton etc says: ‘We have good proxies which allow us to estimate it going back 400 years or so. Google “Judith Lean” or “Wang” + “Lean” for examples.’

    They can’t both be good as they disagree rather much.”

    I thought they were co-authors on the most recent data?

  15. Gusbob, I can only assume you don’t read the news much. We just lost a pretty big ice shelf in Antarctic. Use of proxies significantly extends the estimate of solar stability–and the relatively good agreement of multiple independent proxies argues that the data are being correctly interpreted. There is zero evidence of sufficient long-term solar variation that could “overwhelm” the effects of CO2, which persist of order centuries to millennia–and there’s plenty of evidence against it.

  16. 313 (Hank): The chart is from my poster at last Fall AGU. You can find it at http://www.leif.org/research then scroll down to:
    GC31B-0351-F2007.pdf ((No?)Century-scale Secular Variation in HMF, EUV, or TSI; AGU Fall 2007)

    But the issue is not ‘my’ red curve, but the Lean 2000 and Wang et al. 2005 black curves [the ‘al.’ includes Lean, BTW], which are long published elsewhere. Judith Lean has been kind enough to send me her data. I have put those on my website too: click on TSI (Reconstructions).xls (TSI Reconstructions 1700-present, 2008) [as text, as PDF] just above the AGU poster.

  17. 315 (Ray): “Use of proxies significantly extends the estimate of solar stability–and the relatively good agreement of multiple independent proxies argues that the data are being correctly interpreted.”
    “Gusbob, I can only assume you don’t read the news much”,
    Well, I can only assume that you don’t read this blog much :-)

    The proxies do NOT agree. Not even ‘relatively’. And they are NOT independent [almost all rely on the sunspot number].

  18. Leif,
    Looking at your own data, I’m afraid I don’t see wild disagreement. There is clearly variability, and while sunspot number may not be perfect, do you have a better suggestion? Do you have any evidence that sunspot # is not a good proxy “on average”? In any case we are talking about climatic effects here, so small-scale disagreements in the dark and distant past are not particularly germane.

  19. Thank you for the references and links, Leif.
    Always a pleasure looking at what you provide.

  21. Leif Svalgaard posts:

    307 (Barton): Look at http://www.leif.org/research/TSI-LEIF.png and repeat your assertion that the two black curves look alike.

    I looked at them. They look alike. One has greater amplitude than the other. The inflection points fall at pretty much the same places. Both are still not large enough or in the right direction to have caused the recent global warming.

    You’re not telling me anything I don’t already know.

  22. Plus, Leif, try showing the TSI with the Y-axis extending to zero. That should be good for a laugh. And instructive, to those who insist that solar variations are causing the recent global warming.

    The biggest variations, in Lean 2000, show TSI varying from an average of 1363 W m-2 to 1367. The percentage difference is left as an exercise for the student.

  23. Sure, we have barely a notion of what stars can do, we’re lucky the Arab and Chinese records kept track of the sky over the long term so we at least have some clue what’s changed grossly.

    Just getting glimpses. E.g.
    http://www.journals.uchicago.edu/doi/abs/10.1086/588581

    But none of this changes the climate concern — we have the ocean pH change no matter what happens to warming, and if we did have a decrease in warmth from the sun we’d still have a biosphere to worry about not screwing up.

  24. 322 Barton: try to plot the temperature in Kelvin starting at its zero point and keep on laughing. You keep talking about none of them being large enough to have caused the present rise. I completely agree [might even argue that they didn’t cause any rises in the past either]. My comment was about you saying that we have good proxies of solar TSI in the past. We do NOT.

  25. RL says,”I can only assume you don’t read the news much.We just lost a pretty big ice shelf in Antarctic”

    My reading habits would be one of your better theories. But good science demands that we look at competing assumptions. That’s how science works. Just what does the loss of an ice shelf mean? The Antarctic peninsula has shown warming anomalies when global temperatures have been rising or falling. Perhaps the loss of that ice shelf points to a different driver than atmospheric temperatures.

    RL also says “you don’t even know enough about climate models to argue against them”.

    And in a sense Ray you would be correct. Your models often have so many open parameters its like trying to hit a moving target or fitting an elephant. How did you parameterize the lost ice shelf? You seem to weight that lost shelf more than The National Snow and Ice Data Center’s sea ice data. Now I wouldn’t do that but I don’t know everything.

    http://nsidc.org/data/seaice_index/images/s_plot_tmb.png

  26. Leif,

    I think we may be defining “a good proxy” differently. In my view it’s good if it gives the right shape of the curve and the order-of-magnitude of the values.

  27. Gusbob, Yet another thing you don’t know about climate models–the parameters are to the extent possible fixed independently. Where uncertainty remains, runs can be made over the range of the uncertainty. What matters in terms of model complexity are the adjustable parameters. If the parameters are fixed, then no matter how complicated the model, its agreement with data (e.g. temperature trends) constitutes validation.
    Alternative theories? Great. What are they. I don’t know of any that are credible. And yes, I do weight the collapse of a huge ice shelf that has been stable for centuries more than the extent of sea ice that varies considerably from year to year.

  28. Hey Ray,

    I am catching up on my reading. New Nature article soon to be published predicting “stablized” temperatures due to observed colder ocean currents and that we may see a decade of cooling in North America and Europe. Which GCM predicted that?

    Here’s a link for you

    “Those natural climate variations could be stronger than the global-warming trend over the next 10-year period,” Wood said in an interview.

    http://www.bloomberg.com/apps/news?pid=20601124&sid=aU.evtnk6DPo

  30. Hi all, either moderation is slower than I expected or the diatribe was too much so I will repeat the question I wanted answered by the experts without said diatribe.

    a) Because the question is, I feel, legitimate.

    b) This toned down version is a direct test for the type of censorship that on a superficial basis appears as being applied in this arena. So here goes…

    Question for the climate change experts:

    Would the worldwide use of Hydrogen on demand technology as a fuel source, assuming it’s possible ;-), have any adverse or detrimental effect on GW.

    Thanks in advance
    Cheers
    from a mug punter

  31. Re: #330 (Only Human)

    I’m not a climate change expert, but neither am I completely ignorant. So here’ my opinion:

    Using H2 as a fuel would not adversely affect climate. The byproduct of burning is water vapor, and although that’s a greenhouse gas its atmospheric concentration is quickly (and I do mean quickly!) regulated by environmental factors. So, if we add extra H2O to the atmosphere by burning H2, it’ll precipitate out before it has a noticeable climate effect.

    As for censorship — at this site at least, you’ll find little or no censorship of ideas and opinions, but strong censorship of diatribes.

  32. Tamino, there is some hydrogen/risk stuff worth a look:
    http://www.google.com/search?q=hydrogen+fuel+leak+stratosphere

    It’s hard to even imagine infrastructure built capable of _not_ leaking and wasting hydrogen. The atom’s so small it passes easily through hardware that can hold even helium, let alone the really big gas molecules. You know that of course. But it’s hard to be cynical enough about how careless the below-average guy will be handling something that “just goes away” when it leaks, doesn’t contaminate the water table, doesn’t discolor or smell bad — and does blow up if it accumulates so people really don’t want to mess with it.

    The stratosphere/ozone concerns need evaluation by very jaded cynical observers of how we actually do industry.

  33. Hydrogen is an energy carrier, not an energy source, so its climate effects depend very strongly on what energy source is used to produce the hydrogen. This is a basic fact that is often overlooked.
    That said, hydrogen itself (from leaking when it is going to be used on a large scale) may also have effects on atmospheric chemistry:
    – It may slow down the breaking down of methane, a strong greenhouse gas (by decreasing the amount of OH radical)
    – It may increase the amount of stratospheric water vapor, which could affect ozone destruction (by increasing PSC’s on which the reaction that breaks down ozone takes place)
    See eg http://gcep.stanford.edu/research/factsheets/effects_climate.html
    Hydrogen does not appear to be a panacea.

  34. Re 300: I don’t pretend to be a climate expert either but as an engineer I’d say that just looking at the combustion is too simplistic. In order to assess whether hydrogen on demand mitigataes or contribues to AGW you’d have to look at the entire chain of production, distribution, and consumption, and measure the fossil fuels involved. Then you’d need to compare that to the same chain for conventional fuel the hydrogen is offsetting. Only then could you really assess whether hydrogen would give a net improvement.

  35. Re #330

    Tamino is correct, that burning hydrogen produces water vapour which will condense and then precipitate out of the atmosphere within a few days. This means that it is unable to build to a higher concentration, unlike carbon dioxide.

    However, how are we going to obtain the hydrogen? Unlike carbon, it does not grow on trees! The most obvious method is hydrolysis which requires the generation of electricity, and so the burning of fossil fuels is still needed. Although the power to produce hydrogen could be obtained from renewable resources, that would only mean that those resources would not be available to generate power for other uses. There would be no net gain.

    There is another disadvantage to hydrogen in that it is very bulky to transport. Unlike natural gas it is difficult to liquefy. That problem is solved using fuel cells. They can produce hydrogen “on th fly.” They are sometimes held up as the answer to a maiden’s prayer. But they do not solve the problem of where the power is to come from. They take more energy to produce and to charge than the energy they deliver.

    Hydrogen power is not a silver bullet to the problem anthropogenic global warming :-(

    Cheers, Alastair.

  36. Re #331

    On the earth H2 can not be a fuel since it does not exist in a natural form, unlike CH4 for instance.
    Basically it is an energy transfer medium which can be created from another source (CH4, H2O etc.) with the input of energy and then transported to be used elsewhere (e.g. mobile powerplants). Its influence on climate therefore depends on the method in which it’s made (and source of the energy) and the way in which it is used. The most economic source is reformation of CH4 (at least the last time I looked) which itself creates CO2 (but in a single location so sequestration is possible). Also fuel cells only produce H2O but if the H2 is burned then NOx is also produced. The last time I looked at the overall ‘well to wheel’ analysis of H2 fuel cells it came out that they produced more CO2/mile than present best case SI engines. Sequestration and/or the use of non-fossil energy sources would be needed to get this down. If economic production of H2 using solar energy/bacteria becomes practical then the ‘zero impact’ might be feasible.

  37. Well, in a weak attempt to circle back to the subject, which is our solar system’s place in and motion through the galaxy, this may help us get off the planet in an ecologically neutral fashion:

    http://news.nationalgeographic.com/news/2005/11/1109_051109_rocketfuel.html
    ——-excerpt follows——

    Scientists first discovered anammox bacteria in yeast and later in the open ocean in the late 1990s.

    The unusual microbes consume ammonia, producing hydrazine—better known as rocket fuel—in the process. The ability still puzzles scientists.

    “They are the only organism on Earth that produces hydrazine, so until their discovery, [hydrazine] was thought to be a man-made substance,” Strous said.

    The bacteria safely store the toxic fuel in an organelle, or specialized cell structure, similar to mitochondria, a type of biological power plant found in human cells.

    —-end excerpt———-

  38. The issue of differential rotation speeds is a universe-wide conundrum, requiring the invoking of dark matter to keep the disks and spirals rotating more or less as though they were “solids”. Only being embedded in a MUCH larger rotating mass would “drag” the outer stars around fast enough to stay in a radial line with the inner stars to any degree.

    And of course the spirals are not self-contained “things” like strings or tentacles. They are density waves that move at the interstellar speed of sound, so without much change in its relative radial position at all any give star will alternate between being in the “waves” and in the gaps. The frequency will depend on the density wave frequency.

    There is also the matter of wobble “normal to the plane” of the galaxy. This up and down bouncing will also have the effect of moving a star in and out of the denser populations.

  39. Just a thought about Svensmark’s, CRF/cloud condensation nuclei theory:
    isn’t this theory based on climate data from the 1600’s onwards, correlating with Be-10 as a proxy for CRF? Surely the energies required to produce Be-10 i.e. above 0.5 GeV are too low to provide evidence for Svenmark’s theory. If I understand correctly, he is talking about 10 GeV and above. AFAIK there is no correlation between CRF at 0.5 GeV and CRF at >10GeV.

    [Response: The relationship between the GCR that produce 10Be and the GCR that cause ionization is that they are both modulated by the solar and geomagnetic fields (though to different extents). – gavin]

  40. Yes Gavin, I understand that they are both modulated by the solar and geomagnetic fields, but how can one infer the historic levels of >10GeV from Be-10 or C-14? What evidence is there that they are a proxy for >10 GeV?

    [Response: That relies on an assumption that the modulating factors for 10Be and 14C are the same as for the high energy GCR. There are 11 yr solar cycles in all of them, and so it’s likely valid for that – longer term trends are a little more ambiguous (since there are potential contaminants on those time scales), but there is no a priori reason to think there would be a big difference. However, this is just qualitative – coming up with a quantitative calibration from 10Be/14C changes to muons or solar irradiance is a much bigger challenge. – gavin]

  42. “And of course the spirals are not self-contained “things” like strings or tentacles. They are density waves that move at the interstellar speed of sound”

    Oooh, bad call. Sound travels at 0mph. “In space, nobody can hear you scream”.

    The spiral arms are now thought to be, as you say, density fluctuations. That would make these travel at the group velocity which can be faster or slower than the constituents (even faster than light: shine a torch at the moon and move it sideways fast enough and the spot can move faster than light, despite being light itself).

  43. Thanks for the reply Gavin. It seems to me that the historical data, that Svenmark’s theory relies on, requires a correlation between Be 10 or C14 and >10GeV CR. It is, perhaps, possible to show that they are cyclical together, but there is no proof that the amplitude of >10GeV during the Mauder minimum was particularly high, as Be10 and C14 show all CR with an energy > about 0.5 GeV.

    As the bulk of CRF is at energy levels 1-2 GeV, it’s impossible to get meaningful amplitude data about >10 GeV from Be10 or C14. Since Svenmark’s theory needs >10 GeV to make CCN, I believe that the historical data cannot back it up in any significant way.

  44. > Ooh, bad call
    Ooh, bad call — you can look this up.

    http://www.google.com/search?q=astronomical+cloud+supersonic

    Our ears can’t hear it, but it’s sound nevertheless.

    “… the speed of sound (in the interstellar medium) is about 100 km/s. (The exact speed depends on the density, which fluctuates considerably.) The interstellar medium, although very low in density, nonetheless has a constant pressure associated with it; the pressure from the solar wind decreases with the square of the distance from the star. As one moves far enough away from the star, the pressure from the interstellar medium becomes sufficient to slow the solar wind down to below its speed of sound; this causes a shock wave….”

    You can find photographs of those shockwaves on astronomy sites.

  46. Hank, That’s not the speed of sound in the interstellar medium.

    That’s the speed of the medium.

  47. PS on #344.

    Look at the link.

    Super sonic.

    Faster than sound.

    But how can sound go faster than sound.

    Admittedly, I didn’t click on the link, but given the above, it hardly seems worth it.

  48. Points to consider: the interstellar medium is mostly hydrogen at a density of about an atom per cubic cm. Galactic cosmic rays have a density of abotu 5 particles per cubic cm per second. Much of the interstellar medium is ionized and even that which is not has a magnetic moment, so long-range interactions are possible. Waves do propagate even in this tenuous medium.

    What effect dark matter and energy have is left as an exercise for the reader.

  49. Ray, the cosmic rays are going near lightspeed.

    This would tend to give a flow to any ionised hydrogen if they acted like you think.

    Noe please have a shot at this calculation: what is the electric strength of a proton at 1.5 cm? That’s your ability to conduct sound waves. Not a lot.

    What you can do is have a much denser medium being ejected. When that denser medium hits you, that can produce “sound”. For a given value of “sound”…

    But then again, the sound isn’t travelling in that medium, it is the medium.

    Traveling at whatever speed is appropriate for the ejecta.

    Hey, c’mon guys, I *did* study this at university! Or are you going to be doing a “Rod B”/”Humpty” thing? “That’s not what I meant when I said sound”?

    ;-)

  50. Mark, the median energy of a gcr is ~300 MeV/amu, and while the interaction strength of particles in the interstellar medium is not strong, there is also not a lot to disturb the propagation of any wave. If you look at the solar wind, you definitely find waves, even when fluxes are low. Magnetohydrodynamics is odd stuff