Supernova remnants

This is spin off from Message 35, in a now closed thread. Sorry Adminnemooseus, I did not think about what thread I was using last time. Hi Tiny man,I am the author of the talkorigins feedback item on SNRs which NosyNed has mentioned in the other thread. I write feedback responses under my real name. Sylas is my pseudonym for most other on-line contexts.Do you mind my asking are you the person who sent us that feedback? If so, thanks. We are always glad to have feedback, critical or supportive.One difficulty with feedback, of course, is that there is no real scope for an ongoing exchange. A feedback response has to try and give a reasonably concise response that helps address any issues; but this is still not as good as a dialogue.I'll be happy to address any outstanding concerns you may have. I assure you, we are not lying about the existence of 3rd stage SNRs. I am genuinely concerned with accuracy in the archive, and have on a number of occasions helped facilitate changes to the archive to correct errors.In this case, however, I am pretty sure of the facts of the matter. There several 3rd stage SNRs known in the galaxy. (This is also called the snowplow, or radiative phase.) However, this is not something that is immediately clear. Highly evolved SNRs are very hard to detect, and even if seen it is not always immediately obvious what phase it is in. The Cygnus loop SNR, for example, was considered at one time to be in the radiative phase, but is now considered in the adiabatic or Sedov phase (2nd phase). It is also possible for different parts of an SNR to be in different stages. The full details of how an SNR changes over time are very much a matter of ongoing research.Here are two images of two 3rd stage SNRs in our galaxy, with links to further discussion.
Simeis 147
(Added in edit. If the link above does not work, see the galaxyimages page by the photographer of this amazing image.) Vela SNRCheers -- Sylas Fixed URLs - The Queen
Fixed the name of Simeis 147. I had it mixed up with the Cygnus loop, which is mostly Sedov, partially radiative; a "mutt". - Sylas
Added a more reliable link for teh Simeis 147 remnant. -- SylasThis message has been edited by Sylas, 05-20-2004 01:45 AM

Thread moved here from the Proposed New Topics forum.

your links have "url= http://" with space causing extra http:// to loadwhat are third stage SNR's - apparently not what I thought ...[This message has been edited by RAZD, 04-20-2004]

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

No problems in Opera, you must be using an inferior browser. SNR = SuperNova Remnant, or what's left behind after a supernova explodes.From Supernovae, Supernova Remnants and Young Earth Creationism FAQ: The Life Cycle of a Supernova Remnant:

• In the first phase, known as free expansion, the
  front of the expansion is formed from the shock wave
  interacting with the ambient interstellar medium (ISM).
  This phase is characterised by constant temperature within
  the remnant and constant expansion velocity of the shell.
  This phase can last anywhere from 90 years to over 300
  years.
• During the second phase, known as the Sedov or
  Adiabatic Phase, the remnant material slowly begins
  to decelerate and cool. In this phase, the main shell of
  the remnant is unstable, and the remnant's ejecta becomes
  mixed up with the gas that was just shocked by the initial
  shock wave. This mixing also enhances the magnetic field
  inside the remnant shell. This phase can last anywhere from
  100-100,000 years.
• The third phase, the Snowplough or
  Radiative phase, begins after the shell has cooled
  down to about 1,000,000K, so the shell can more efficiently
  radiate energy. This, in turn, cools the shell faster and
  thus making it shrink and become denser. This makes it cool
  faster still. Because of this snowball effect, the remnant
  quickly develops a thin shell and radiates most of its
  energy away as light. The velocity now decreases fairly
  rapidly. Outward expansion stops and the remnant starts to
  collapse under its own gravity. This phase can last
  hundreds of thousands of years.
• The fourth phase, known as Dispersal. Here the
  shell breaks up when the velocity of the "snowplough"
  becomes subsonic, and what's left of the remnant dissipates
  into the ISM.

See Supernovae, Supernova Remnants and Young Earth Creationism FAQ: Are Supernova Remnants evidence of a young Universe?.

SNR is supernova remnant; the cloud of debris resulting from a supernova explosion. There is a kind of idealised model for how a remnant changes over time, established in the 1970s, which is broken into distant phases, as JonF has explained.It should be emphasized that this idealised model is theoretical; based on application of physics to simplified conditions, in which spherical shells expand in a uniform and thin interstellar medium. It is not based on a classification of observed remnants; and fails in many cases as a convenient way of classifying what we do observe. This is explained also on the FAQ which JonF cited.The phases are reasonably well defined in terms of different kinds of expansion as ejected material interacts with the medium in different ways; but different parts of the same remnant can be in different phases, and the duration of phases varies enormously. There is considerable degree of inference and observation required to match these distinctions to observation; it is not straightforward to distinguish the various kinds of expansion.Nevertheless, I believe the two remnants I showed previously are behaving in a manner characteristic of the idealized third snowplow phase, and qualify as counter-examples to the creationist claim that there are no third phase SNRs in the galaxy. The FAQ gives a number of other examples; but such old SNRs generally do not make good images. These objects are enormous, and very faint. The Simeis 147 image posted previously required more than eight hours exposure time. Its apparent size in the sky is more than six times larger than the full moon.For a more technical consideration, see 10^51 Ergs: The Evolution of Shell Supernova Remnants (1998). Here is an extract: Radiative, or snowplow, or third phase SNRs were considered in the workshop, and they came into both the "mature" and the "old" categories; but do note that there was a strong feeling by many in the workshop that Woltjer's classification scheme needs to be reconsidered.Cheers — Sylas

thanks. use netscape and load links to new tab, saw the error there and fixed for myself. pretty pictures.info good. I had wondered if it had to do with stages of stellar evolution ... wondering what a third stage star would be.

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

Hi there Sylas:
I sent this message via email, but appearently it may not have arrived at it's destination successfully as I recieved an error on sending, so I will just copy and paste. Yes, I did post a questioning and skeptical view about the Talk Origins article. Thankyou for responding. I have been giving the forums a break for now, as if you post one message you get a thousand replies all trying to argue with you. I am waiting for the starwarskids.com forums to become up and running again. Just before I start, I would like to give you a little background info on me. I am only 17 so I don't really know all that much on creation and evolution. I know enough to get me through any argument easily enough. Shortly after I saw the talkorigins.org article on 3rd Stage SNRs I sent a question to the people at Answers in Genesis for their response. I was also given a list of so-called creationist lies from some people of 4forums.com- http://members.cox.net/ardipithecus/evol/lies/lie018.html - (some straw man attacks) in which they tried to twist the evidence when they quoted Clark and Caswell's quote where they claim the mystery of the remnants "is also solved". The following is part of the reply I recieved from AiG feedback:"But what this site [listed above] fails to mention is the rest of the quote:
"It appears with the above explanation there is no need to postulate values of Eo/n differing greatly from those in the galaxy, and the mystery of the missing remnants is also solved."
Well, to what explanation are they referring to? The explanation is that IF:
1. There was an incorrect estimate so anomalies should be included.
2. Assume the detectino limit is expanded by a factor of 3.
3. Claims that there was an erroneous number detected by a factor of 2.So basically the Clark and Caswell made up assumptions to try to fit the evolutionary model. Basically they said that since the data didn't match evolutionary premises, they would assume that it was an incorrect estimate, the detection rate is wrong and anomalies should be included, they they conclude that this fits with evolution. This doesn't solve the problem (and is an imbarrassing interpretation) but shows their allegiance to evolution over the observed facts, which was what Dr Sarfati commented on.Dr Sarfati was telling the truth and the author of the article you sent was the one concealing the truth. Talk Origins is known for doing this sort of thing and they sound convincing until you read the details and many have fallen into their lies....."The information on those pictures you posted mentioned nothing about what stage the SNRs were. Aren't the 3rd stage SNRs supposed to be really hard to detect, are notthose two you posted seemed pretty bright and easy to pick up. Perhaps these are just merely stage 1 or 2 SNRs. I think that I will have to go with the creationists on this one, besides, as Christians they are bound by God's Word which says not to lie. The AiG feedback goes on:
"As atheists, lying and telling the truth are neither right nor wrong. Evolutionists believe in the "survival of the fittest" mentality instead of "love thy enemy". So they afraid to lie to make themselves appear better..... Obviously, they [evolutionists] believe that their interpretations as fact and anything that doesn't fit with their interpretation is a lie in their eyes."Also, for the SNR Semeis 147 appearent age of 100 000 years, isn't this already flawed? I am not completely sure here, but this is where General Relativity plays a major part? What you and the evolutionists are saying is that since the SNR is about 100 000 light years away (to which I agree), the SNR must be at least 100 000 years old. Basically, 1 lightyear = 1 year. But think that this assumption is wrong. Einstein's GR also applies to gravity (gravitational time dialation), does it not? Time slows down in high gravity and speeds up in low gravity. This was first measured by comparing two identical atomic clocks at the Royal Observatory in Greenwich with an atomic clock at Boulder, Colorado, about a mile above sea level. The difference is about 5 micro seconds per year - which came out in line with what GR predicts for the one-mile difference in altiude.So it can be shown that gravity affects the flow of time. Now we can apply this same concept to space and the universe. There are many parts in space with which there are different gravitational field strengths, some high, others very low (relative to the Earth). These differences in gravity bring in different frames of references [and the screwy part of GR]. Let us use an example to help us to visualise this. As one day proceeeds on Earth, the more distant stars age billions of years, while their light also has the same billions of years to travel to the Earth. The above is just an example and most likely happened during the Creation Week.So the evolutionists are ignoring the Measured Effect of Gravity on Time. What Stephen Hawking does is just assume that there is no differences in gravity anywhere in the universe -- but we know that there is lots of differences in gravity all over the universe! So his assumption is wrong, and with that goes the idea of an old universe. With the assistance of GR and a different starting assumption, i.e. that of a bounded universe - big bang assumption is an unbounded universe - (and the evidence, such as red shift, CMB radiation) we can have a big universe that is a young universe. For more information I would strongly suggest that you buy or take a look at Dr Russell Humphreys book titled "Starlight and Time". It is a really thrilling application of science. I am not quite sure about whether or not I am correct with my GR application with gravity. I think that I have it right, but I am not quite sure. I seems to make sense that 1 lightyear cannot equal 1 year (E.S.T - Earth Standard Time). I will talk to my physics teacher about it. But I do know that a light year is a measure of distance not time, as the evolutionists appear to be taking it.Best wishes,
Matt.----- Original Message -----
From: Sylas
To: matthew@manpro.com.auHi Matthew,I'm Sylas at the EvCforum, but I also answer feedback for talkorigins.
I'm not entirely sure, but I think you may be the person whose talkorigins feedback I responded to on the matter of supernova remnants last month.You also mentioned this topic at the EvC forum. This is just a courtesy note to you, to let you know that I've responded on supernova remnants at EvC in a thread at the following URL:
http://EvC Forum: Supernova remnants -->EvC Forum: Supernova remnantsI wrote in response to your message "Skeptical of talkorigins.com", at
EvC Forum: Was Nebraska Man a fraud?However, since SNRs were off topic for the thread, and since the thread had been already diverging wildly from the original topic, the thread was closed by moderators. I made the new thread so that you would be able to discuss your concerns the accuracy of the information we are presenting.Your under no obligation to respond, of course; but if you want to ask anything please feel free.Best wishes -- SylasThis message has been edited by Tiny man, 05-09-2004 04:48 PM

Ah, youth!You'll learn, Tiny man.

I'll let Sylas reply to the technical questions. This kind of gratutious and false insult should alert you to the real motives of the AIG crew. Is that a Christian attitude to take? Is taht loving your enemy?For your information, many "evolutionists" are dedicated Christians who are following the ways of Christ as best they can. Most atheists and agnostics have strict moral codes that makes lying wrong in their eyes. Nobody is claiming that anything that doesn't fit with our interpretation is a lie ... but we are claiming that the repeated and egregious misrepresentations and hiding of evidence by AIG are lies.

quote:

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As atheists, lying and telling the truth are neither right nor wrong.

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I suppose that this means that we atheists feel we may as well lie if it advances our agenda.On the other hand, if we atheists don't believe in a right or wrong, why do we care so much for advancing any agenda?

I have checked the links provided to Sarfati's little essay.Sarfati does indeed state : Astronomy | Answers in Genesis He does NOT make any mention of the fact that Clark and Caswell consider the mystery "solved".So it can be seen that Sarfati did NOT tell the truth about that.Your criticisms of Clark and Caswell need to be properly documented, including dealing with the evidence they used. Your 1) is inaccurate - they argue that an estimate based on a small sample may be incorrect and that taking an alternative value solves the problem.
Your 2) has no basis in anything in that section
Your 3) appears to be a misreading.I have yet to see any reaosnable evidence of a lie in any of the talkorigins.org FAQs - not even one comparable to to misrepresentation of Caswell and Clark that Sarfati is guilty of.As for your comments on time dilation, I really suggest that if you want to propose that an intense gravitational field is affecting astronomicla observations that you should start a topic on the matter - and producing evidence of such a field.

Thanks for responding, Tiny Man. I don't know why the email failed; sorry about that. My email address is in my profile here. I am going to skip over questions of who is lying or not, as I don't think that helps anyone. Let's focus on the models and the data. As I explained in Message 5, the whole idea of first second and third stage SNRs is a highly simplified theoretical model. The basic distinctions are meaningful, but the development of SNRs does not fit the very simplified model first proposed by Woltjer and subsequently used by Davies. However, the two SNRs that I listed in Message 1 are indeed "third stage", as far as we can reasonably tell, although this nomenclature is not usually used these days, for the reasons given above. The two SNRs pictured are very hard to detect indeed. For example, the image I showed of Simeis 147 in Message 1 took over 8 hours of exposure time. That is, you keep the shutter of the camera open for eight hours, being very accurate in tracking the account for movement of the Earth. See also the linked discussion of the Vela SNR image to get an appreciation for the difficulty in making these images. Because mature SNRs are so large, they cover a lot of sky, and they get mixed up with other sources in the same line of sight.Added in edit. The Vela SNR is described as third stage in: There are several points to note here.

1. This is not about evolution, but astronomy.
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2. I did not say anything about the distance to Simeis 147. Actually it is about 3,000 light-years away, if this matters. In my posts, I was speaking of age in years. The remnant is about 100,000 years old, measured not as the time it takes for light to reach us, but as the amount of time between the explosion and the current spread out remnant.
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3. You can't have this one both ways. If the SNR is indeed as old as 100,000 years, then the whole basis of Davies' critique is falsified. Essentially, you are invoking two conflicting ideas. One is the universe does not contain things that are very old. That is the fundamental hypothesis of the Davies paper on supernova remnants. The other is that the universe does contain things that are very old, but due to the effects of time dilation the Earth is actually only several thousand years old. Which one are you proposing?
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4. The effects of gravity on space and time are subtle but uncontroversial, and routinely taken into account in astronomy. One consequence of the gravitational time dilation is that light changes frequency as it moves in or out of a gravitational well. This effect is well known. It has been directly observed in Earth, and in the light from distant stars. We have observed gravitational redshifts corresponding to time dilation in light coming out of a very dense dwarf star, detected by comparison with light from a binary companion.
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5. The gravitational time shift model you mention is the one described by Russell Humphreys, in Starlight and Time. This works in reverse, as if Earth was in a gravitational well, and signals from the rest of the universe spread over billions of years are compressed to within thousands in Earth. This conflicts with all available evidence. There is no sign of such gravitational fields. A direct consequence of such an enormous dilation would be massive blueshifting of light from the rest of the universe; no such thing is observed. The light curves of distant supernova (the explosions themselves, not the remnants) have been measured to check models of the cosmological red shift; they confirm that signals from deep space are in fact stretched in the opposite direction to that required by Humphreys model. This is a whole other topic, but basically gravity does dilate time, and we do measure and detect this effect, and the particular kind of dilation and gravitational field invoked by Humphreys does not exist.

However, at least Humphreys confirms that things in the universe are very old.I also refer you to a very thoughtful and comprehensive answer to your underlying question at the Ask a High Energy Astronomer page, in a question specifically about claims that SNRs are all under 10,000 years old. See Can you refute claims that the Universe is only 10,000 years old? in the SNR question category.Cheers -- SylasThis message has been edited by Sylas, 05-09-2004 10:42 PM