Okay, so let's get down to some concrete examples on why I distrust peer review with regard to novel scientific thought (my first topic from last week). This also touches on several points just made in the FTL / Tom van Flandern topic next door. (i.e. Tom's theoretical work on Mars does not relate much to the face on mars / cydonia, though he has favorably "peer reviewed" and published some others work in this area (Carlotto and so forth)).

Remember, I am not a scientist. I don't read the technical journals, I get my observations mainly from the mass-media, or the nearly mass media. Plus, for better or worse, I've had this close connection to at least one scientist who is "bad," and have read about others.

This addresses, in part, the question of whether Tom has too many gripes with the mainstream, and whether he offers predictions along with his theories that are testable (i.e. does he follow scientific method)?

So, for example...

Just yesterday I read in Science News (Dec. 14 2002, vol 162, p.372) about a "new" idea regarding where martian water might have come from (I'm a little behind in my reading. That, and I get my copies of Science News delayed from someone else who actually has the subscription. It's a good thing: recycling).

The new idea is that the water was brought from impactors onto mars. Comets and asteroids contained the water and deposited it on Mars during some epoch when they were crashing into the planet a lot (according to authors, Segura and Toon, in the early solar system some 3.5 billion years ago. A paper was published in the Dec. 6 Science).

(First I've got my own complaint on this: martian water features are no way 3.5 billion years old. They would have weathered away by now. I mean look at how badly the Face on Mars has weathered in merely 3 million years!;-)

Toon is quoted: "This is a new idea, and there hasn't been a new idea in this field for quite some time now."

But this is what Tom van Flandern has been shouting out for at least a decade:

1. that martian water is not from mars
2. that martian water is relatively young
3. that martian water was short lived (in surface liquid state).

in sum that martian water came from off planet, from impacting debris. Specifically, debris from a larger water-rich planet that broke up or exploded nearby. (Tom posits that Mars was a moon of this planet).

Tom's planetary science work is centrally anchored by his Exploded Planet Hypothesis (EPH), and with this theory he has successfully explained many long-term enigmas in Solar System science, and made successful predictions, as the scientific method requires. But he continues to be ignored.

(For example he also predicted that Mars "cratered" side would have the thicker crust, and the smooth side the thinner crust. I believe mainstream thought had been the reverse until recent orbiter observations showed the opposite. Surprise! Did everyone follow all those reversals?)

Of course, the biggest problem in EPH is that no one has ever seen a planet explode all by itself, therefore it cannot happen. (Or have they? Things are always exploding/bursting all over the universe, it seems...) Or because the explosion mechanism is unknown (That's why the sun couldn't shine prior to the 1940s). It's just like large meteors can't wipe out whole ecosystems on earth, because no one has ever seen that before either... (Uh, I guess mainstream thinking has finally come around to the plausibility of this).

(And for another topic: TVFs EPH theory predicts not just one or two big impactors for given earth epochal events, but waves of many hundreds of impactors scattered across the globe. Recent news is that these boundaries like KT, archaeologists keep finding more and more impact craters for a given boundary.... his prediction is being verified, folks).

What's the most galling is that even as van Flandern makes successful predictions, his work is ignored by the very people who will then claim to have new ideas about the matter, when they finally come around to seeing it his way. But I suppose one can't blame them, because these are the same population of people who (appear to) block Tom's attempts at getting published... so how could Toon have known otherwise?

Ideas?

Boris

Something a bit nitpicky first...
What it could be is that the water was introduced 3.5 billion years ago, stuck around for a while, created those martian features, and then through some process disappeared from our view.

I think that another way to possibly support his argument would be to find debris orbiting the sun in a plane at some angle to the ecliptic (the plane in which the planets generally orbit around the sun). When Mars' partner blew up, it would've sent debris flying in all sorts of directions. I'm not sure how likely it is that some would follow a similar orbit to Mars but angled - the debris would probably be very elliptical and hard to find. However, if anything like that is found - a fair amount of debris with similar orbits, that pass close to Mars' orbit but are angled off the ecliptic - I'd think it'd help his case for sure!

__________________
Tristo è quel maestro che non venga superato dal suo allievo
-Galileo Galilei

That is one of the foundations for Tom's exploded planet hypothesis (EPH). The debris is found all over the place: asteroids (and more recently TNOs) and comets. The debris has evolved over the past several millenia into these two populations because the major (remaining) planets sweep up the rest.

So if at first you had debris moving rapidly away in all directions (actually there is a full range of velocities and directions). What remains for us to observe are:

1. the asteroid belt(s) - slow moving debris not yet swept up (and not likely to, because of the unique orbital parameters - I.e. this is the "lucky" debris)

and

2. comets - fast moving debris, where the resulting orbits are so large that only a few passes through the solar system have occurred since the explosion event. In effect comets are the same debris that has had less exposure to the inner solar system in the epoch since explosion.

One thing the EPH predicts with respect to asteroids and comets is that they are basically the same thing - therefore one can predict a minority of objects that will form a continuum between them. So you do see a few earth orbit crossers, a few semi cometary asteroids (i.e. asteroids with occasional comae). Another big prediction that Tom made with his EPH is that most if not all asteroids will have satellites. A VERY bold prediction to make (made over twelve years ago), and it has been largely verified.

Another thing the EPH predicts is that the KT boundary (and other evolutionary epoch boundaries), which the mainstream has now come around to ascribing to large impactors, are really the result of multiple impacts, not single impactors. Tom believes that after a planetary explosion event (he sees evidence for several in the solar system), the remaining planets are peppered with impactors for months thereafter. Sounds reasonable to me, and indeed results keep coming in from archaeology, that the KT boundary was the result of multiple impacts.

And then there's the predictions about mars, which gets us back ON TOPIC.

Okay, I started three threads today, now I have to go tend to my life.

See you all tomorrow and thanks!

Boris


posted 8/29/3

No, I think the biggest problem is that he has no empirical support for such a theory. Or a mechanism. It is not enough to point to the asteroid belt and claim that as support for the theory. There is an existing explanation for the asteroid belt. Is there a reason that TVF's explanation should be any more compelling? And since the sum of all the masses of the asteroid belt don't add up to anywhere near the mass of a small planet, that alone would seem to falsify the assertion.

And predictions are fine, but predictions of events that could occur for any number of reasons do not exactly instill the greatest confidence in one particular theory.

What? These things have vastly different compositions! Comets are essentially dirty snowballs. How could they survive a birth from an "exploding planet"? The more I hear about Van Flandern, the more I think, "Preposterous."

__________________
Everyone is entitled to his own opinion, but not his own facts.

Cougar,

Have you ever considered reading Tom's original reasoning before opening your mouth in your regular out-throwing of dumb disbelief?

AgoraBasta, in case you come back to read this thread...

I posted a warning in the other thread where you insulted a poster, but didn't know about this one. Two major FAQ infractions warrants no sympathy from me. Goodbye.

__________________
Phil Plait
The Bad Astronomer
http://www.badastronomy.com
badastro@badastronomy.com

It's true AgoraBasta gets a little too colourful at times, but in the threads I have seen he has tended to make them more interesting. If he's from Russia he may also be used to a sharper debating style than here. How about letting him have three strikes before tossing him?

Two is enough. Read the FAQ. I don't care what style of debate people are used to in other venus. They will be polite to one another when debating here.

Empirical evidence for the Exploded Planet Hypothesis

Cougar:

You wrote a little but there's lots to reply to... I agree with much of what you say here, theoretically! But the devil is in the details, as usual. Do I need to start another topic?! I think I will. A lot of this has nothing to do with mars...

No empirical support? What does that mean exactly?

For example: if I were to walk along in a grassy field, and I come across a big hole in the ground, with debris scattered all about, would that be empirical support for a theory that an explosion had taken place?

If I then theorize there was an explosion, I might make some predictions. (I reason deductively!) I might predict that I will find chemical residues, for example. Or I might predict that I find grasses burned. Then I make more extensive observations to test my theory against those predictions.

Also, just because I don't have a mechanism right off the bat, doesn't invalidate my theory. So what do you mean, exactly, by empirical support?

That's exactly right! That's why making predictions through deductive reasoning based on your theory is so important, contrary to your dismissive remark regarding predictions!

Returning to my analogy in the grassy field, if instead of the chemical residues I find a shovel nearby, I might have to change or even abandon my theory. I might make a new theory: someone used the shovel to dig the hole. Or I might patch my old theory: the shovel was blown out of the hole by the explosion. All this leads to new predictions to be tested: Are there fingerprints on the shovel? Is there chemical residue on the shovel?


Well, yes of course there is already a theory explaining the asteroids. So you mean one should stop there? No, no, this is Science not religion! This is Astronomy! There can be no advance without skepticism!

Look, when I was a kid I learned about asteroids like the rest of us, and it seemed plausible enough. Actually, I had read some older books, where sort of an exploded planet theory was still being taught (call it the "broken up" planet hypothesis). That actually had a better ring to it! But what did I know? Having the asteroids be a planet that never formed seemed just as fine, and repeating that theory got me good grades!

Same for comets (which, I insist, relate to this topic). The Oort cloud seemed a fine theory. It explains perfectly the randomness of direction, orbit, and arrival times of comets, as well as their seeming primordial nature. After all, everyone knows they are hunks of ice left over from the birth of the solar system, how else would you get all that gas and dust sublimating off the nucleus?

The point is these are the things we were taught, and to some extent such teaching closes the mind. We don't go out looking for other answers.

Tom van Flandern's position is quite different from ours though, and I recognize this as an opportunity to see the world from another perspective. He is a celestial mechanicist, whose professional career consisted of calculating orbits of Solar System bodies. Most of his theorizing is based on this foundation. It might be a boring foundation, but it is very, very solid.

(I sound like I'm rambling here, but really this pertains precisely to your points above)

So Tom spends twenty or thirty years analysing orbits and observes some pretty strange stuff. He sees the strange orbital system of Uranus. The oddity that is Pluto's orbit (as well as the oddity of the relatively huge satellite). The asteroids and comets. The earth crossing asteroids, etc. Along the way he notices other strange things like the assymetrical coloring of some solar system bodies (Iapetus I think it is but I can't recall just now). I say "strange" things, but I mean things that are simply unexplained. So all these things are in need of a theory, so to speak. They may all get their own individual theory or...

And one day (I don't actually know how suddenly the theory came into his mind) he says, wait a minute, all these things have something in common. When you find a lot of strange things with something in common, you give a pause. There could be a causal link. This is like finding the hole in the ground with debris scattered all about. You notice the hole and theorize. Another fellow notices the debris and theorizes. Along comes a third fellow and notices both things at the same time!

This is partly the answer to your question "Is there a reason that TVF's explanation should be any more compelling?" It is that TVF's EPH explains all these things. AND allows him to make remarkable predictions. (Frankly I totally don't understand your dismissal of the importance of predictions. predictions are the only thing we have to test theories. Any fool can observe something and make a theory; it is the tested predictions that matter in solidifying theory. Theories are not tested by whether or not a mechanism is understood, or whether or not they sound reasonable. That is not scientific.)

To address your comment about comets and asteroids being separate items completely, let me turn the table around. Let's discuss the current comet model. On what basis was the Oort cloud theory developed? Wasn't it simply to explain the randomness of comets? The fact that they appear to come from "everywhere?" Good idea. But how do you test the idea? What predictions has the Oort cloud theory made? What TESTs has it passed? And since you mention the need to understand the mechanism (I disagree with the need to know the mechanism, but I'll take it up in this attack on Oort), doesn't the "passing star disturbing the Oort cloud" seem a little farfetched? Has this actually been observed?? I didn't think it had. As far as I'm concerned, the mechanism for knocking comets out of the Oort cloud has not been demonstrated. THAT part of the theory is pure speculation. Which is fine with me as long as the theory can make some other predictions and pass some tests.

You also mention the "dirty snowball" model for comets, which I think is ironic. The "dirty" part of this model is itself a PATCH to the original theory that comets are icy primordial remnants. Observational evidence came in (as telescopes got more and more powerful - yet were still unable to resolve the nuclei of comets) that the nuclei of cometary nuclei must be of very low albedo. These observations in effect falsified the theory that they were icy. Subsequently the theory is patched: Oh, they must be icy remnants with a dark "dirty" surface. Current research tries to theorize how the surface got so dark.

It all sounds reasonable. But note that this is an example of where a theory is made (comets are icy bodies) predictions follow (cometary nuclei must be high albedo), predictions fail (nuclei turn out very dark). At this point you can abandon your theory or patch it. But the failure in prediction remains, and in my view weakens the theory.

Finally I'd like to address your two specific concerns regarding the notion of an exploded planet (aside your complaint that no one has proposed a mechanism, which I'll grant, for now).

You say:
And since the sum of all the masses of the asteroid belt don't add up to anywhere near the mass of a small planet, that alone would seem to falsify the assertion.

and:
Comets are essentially dirty snowballs. How could they survive a birth from an "exploding planet"?

These concerns sound reasonable and do seem to falsify the theory. BUT...

Who said all the debris has to remain behind? That is the old planet "breakup" theory. This theory is different. The planet EXPLODED fer cryin out loud. Poof! Vaporized! What little remained of it went into very very large orbits (comets), and even less remained in relatively stable nearby orbits (asteroids). Some other small fraction was swept away or swept up by the gas giants (witness their increasingly, ridiculously numerous harems of satellites - another PREDICTION of the EPH)

As for the survival rate of "icy" comets in a planetary explosion, since we don't know the mechanism I can't say why any fraction of the planet survived at all. There's just no way to know that right now, and it is part of the mechanism, which I propose (again) is largely irrelevant to testing this theory. (Besides which I've already given you a HINT that comets may not be icy. They may be mostly rocky. And THAT is called a prediction. And by THAT you and I may someday know whether or not this theory is worth anything.)

Now I came on this BB to find people to educate me and disabuse me of all these crazy notions. I hope I've not come in vain!

respectfully!

Boris

Other Venus? Surely, you're not suggesting an Venus X, or an antivenus, or maybe an intravenus...

What possible mechanism could cause a planet to explode? The energy requirements to actually lift an entire planet out of its own planetary are pretty extreme - far beyond what any known naturally occuring energy source could supply. You'd have to somehow transform a large fraction of the planet's core into antimatter or something similar.

That's exactly right Boris! This is how it often works - the empirical evidence accumulates before a theoretical explanation. New ideas always face this challenge. Supporters of the mainstream view say, "well then how does that happen." - which of course misses the point that empirical evidence can show something appears to be happening before the explanation as to why it is happening is figured out.

Such was the case with Wegener's continental drift. He had a lot of empirical evidence that favored his idea, but he couldn't explain HOW it was happening. And a plausible mechanism was needed before the mainstream would accept the idea.

But proponents of the new ideas must face the reality that the mainstream probably will not be swayed without the mechanism - no matter how compelling the empirical evidence.

The difficulty with some of the ideas mentioned in this thread is that there has to be a problem which the new idea explains better than the current ideas. If that is shown, then the mechanism question becomes more important.

Continental Drift, or Plate Tectonics in its latest incarnation, is a great example, because its development is often seen as straightforward, but it was actually very complicated.

Some of Wegener's data in support of his hypothesis was outlandish--I seem to recall that he had measurements that showed that Europe was drifting away from North America at the rate of a few meters per year. When you latch onto something that crazy, it taints the rest of your theory.

Plus, in the case of Plate Tectonics, we still don't have a suitable mechanism. Tim Thompson and I discussed this a while back, although I'm not sure we came to a resolution.

But, in the sixties, the magnetic stripe data that clearly showed sea-floor spreading did not necessarily point to plate tectonics--at the time, the ideas about mantle viscosity showed that mantle convection could not be supporting drifting continents. In fact, one of the first researchers to notice the magnetic stripes thought to himself, "hey, maybe old Carey was right!" Carey was the guy who stumped around the world advocating the Earth expansion hypothesis--which we've also talked about on the BABB.

There's a fine line between the cutting edge, and the lunatic fringe.

I remember back in '93 - when I was finishing my Master's - having a conversation about the mechanism of plate tectonics with the Geology professor that I was working with as an assistant. He said "I don't think they've got the mechanism right."

I'm still inclined to agree today. One thing that has always bothered me is that the transform faulting along the Mid-Ocean Ridges doesn't seem consistent with simple convection models, but I haven't read up on the latest thoughts on that one. Are there any models that account for plate motions which do not involve convection as the mechanism?

The expanding earth models do need to account for convergent boundary conditions because the geologic evidence seems to favor that collisional boundaries are real.

A good reason for everyone to remember not to go labeling people as lunatics until the matter in question is resolved.

As far as I know, TVF is not a fan of earth expansion. (Has anyone heard otherwise?). But an EE type of explanation could help his exploding planet hypothesis, if we take into account that the smaller bodies are perhaps more likely to fracture if an expanding force of some kind is applied, rather than to expand, like larger, more fluid bodies such as the Earth.

Expert Man:

Tom Van Flandern does not need an expanding Earth mechanism for his EPH. He already has a pretty good mechanism developed (this is more recent work, published - natch - through alternative channels). The mechanism is closely linked to his Meta Model / c-graviton gravity theory. Here's a hint: his gravity model is a Le Sage type "pushing" gravity. The pushing particles carry momentum, and pushed matter obtains momentum/energy continuously. If the energy cannot be re-radiated away, it builds up...

We would have to start a new topic to get into that. We've gone quite afield here on the topic of Martian water. In fact, I'm rather disappointed that of all these posts, none refute Tom's thesis that Martian water came from off-planet. Oh well.

Oh, I don't dismiss the importance of predictions. I'm just pointing out that putting forward a possible explanation for the known configuration of the asteroid belt and long-period cometary orbits does not constitute a prediction in my book. It constitutes a possible explanation. And from what I've heard, the predictions van Flandern does make might be explained by any number of theories.

My mind is quite open to theories that are well supported by evidence, that is, evidence that cannot be explained in any number of ways.

What's so strange about the orbits of these bodies?

Uranus's orbit needs a theory? Asteroids, comets, earth-crossers... I didn't know these solar system features needed a new theory requiring the suspension of the known laws of physics.

It's not obvious to me how an "exploding planet" explains these things. Does van Flandern have a computer model of an exploding planet that results in something like the asteroid belt? I have a little experience with gravitational models, and I am highly skeptical that an asteroid belt would be formed by an "exploding planet."

You seem to be talking about the Nemesis theory, which is indeed a speculation as to the cause of periodic mass extinctions, not a theory about the formation of the Oort cloud.

Fact is, extraordinary claims require extraordinary evidence, and I'm not seeing it.

__________________
Everyone is entitled to his own opinion, but not his own facts.

You must not be replying to my last post, because that's not what I said. I never got into the predictions that the EPH makes, I was just doing some groundwork, giving you the opportunity to ask, if need be. In other words, I did not assume you were unfamiliar with Tom's theory, since you are, after all, here arguing against it.

You don't seem very curious about astronomy. I invite you to inform me what "known" law of physics turned the Uranus system on it's side. If you don't think that needs a theory...

As far as your "little experience" with modelling orbits, do you think it matches Tom's FORTY YEARS in the field? Why do you even bring that up?

Let me re-phrase that for you: What _mechanismm_ makes comets come out of the Oort cloud to disturb our peace in the inner solar system?

Thanks,

Boris

Thanks for the reminder. I am familiar with Tom's model, but forgot he was linking it to his EPH too.

There could be some problems with Tom's thesis here. The evidence for past liquid water on Mars is found mostly in the Highlands region. This is the heavily cratered older region of the surface, some 3 billion years older than the smoother Lowlands region. If water came to Mars on an impactor, we might expect to see evidence for liquid water all over Mars, since the collision event would presumably have generated much heat planet-wide (unless Tom is calling for a low-speed collision of some sort). But we don't find such evidence.

I would say the pattern of water flow on Mars is more consistent with an "expanding Mars" model. (See the topic "Origin of Life on an Expanding Mars" of a few months ago). Early on Mars may have been warmer and liquid water caused channels to appear all over the surface. Much later, the Lowlands region was gradually formed as new surface crust appeared (analogous to the new terrestrial crust formed at mid-ocean spreading ridges). By this time the surface of Mars would have been cold and so the young surface shows litttle evidence of liquid water flow.

Also, you mention at the start of this topic that Tom successfully predicted the cratered side of Mars to have a thicker crust than the smoother side. This prediction is also made by the expanding Mars theory, since the Highlands region here corresponds to the continental areas of the Earth, which have a much thicker crust than the ocean basins.

I've picked up snippets here and there. I do find it curious that so few of the details of TvF's actual assertions and predictions find their way into these threads. I sometimes wonder if the purpose of these challenges to mainstream, peer-reviewed science is simply to sell a few more of van Flandern's books.

The question was, "It's not obvious to me how an "exploding planet" explains these things. Does van Flandern have a computer model of an exploding planet that results in something like the asteroid belt? I have a little experience with gravitational models, and I am highly skeptical that an asteroid belt would be formed by an "exploding planet."

From what I've heard, van Flandern theorizes that 3 million years ago a planet within our solar system explodes (somehow - don't ask me how) and creates the asteroid belt and the long-period comets. From my modest study of gravity and gravitational interactions, such a result seems unlikely. I realize that arguments from incredulity mean little, but I'm not arguing such a result could not possibly happen. I'm asking if van Flandern has a detailed model or calculations justifying such a conclusion. Forget the complete lack of justification for a planetary explosion, how does he rigorously justify this unlikely result of such a hypothesized catastrophe?

__________________
Everyone is entitled to his own opinion, but not his own facts.

Would you please be so kind and offer me more than just incredulity and ad-hominem attacks in your rebuttals? Tom was reduced to publishing books, in the popular market no less, because the mainstream journals AND academic book publishers have shut him out. After Velikovsky, and a subsequent boycott by astronomers of Velikovsky's publisher, the publishers have learned their lesson to toe the line. The result has been a publishing environment hostile to new ideas, regardless of merit.

I'll be glad to answer your new questions, but hope that you will return to some of the questions I asked you in my last post.

I'll allow your skepticism, although I suspect it has more to do with extra-ordinariness of planets exploding than with what the debris might look like. Tom's EPH is founded on celestial mechanics analyses of comet orbits. Through an analysis of periodicities he not only surmised they had a common origin in time, but also dated the event to 3.2 million years ago. I am currently researching the exact published sources, but please bear with me, I'm in the middle of an office move and my schedule is badly disrupted.

By itself, this is a pretty extraordinary theory, and as you suggested earlier, it needs extraordinary evidence, and as I like to emphasize, it needs to make good predictions. What is extraordinary about the evidence and predictions is that they are made all over the Solar System (as you would expect from such a cataclysm). Thus Tom has made successful predictions not only with respect to comets and asteroids, but also with respect to the nature of Mars, and other planetary anomalies.

Since you've only heard "snippets" I propose we start another topic on the EPH to discuss non-Mars related evidence and predictions. Specifically we can start with your answer to what is the Oort cloud mechanism for injecting comets into Solar System, and why Uranus system is tilted on it's side (using known physics), which is pretty darned odd.

Boris

reply to experdman on mars water source / impactor

A prediction of the EPH is that the heavily cratered highlands are younger, naturally the result of bombardment 3.2 million years ago. This also explains the thicker crust there. Note that mainstream theory calculates the age of terrain by counting craters. This assumes knowledge of cratering rates over the history of the Solar System, which the EPH challenges directly. (In fact, a recently noted second epoch of older craters underneath the primary craters in Martian highlands is also explained by the EPH, because planetary explosion is treated as a non-extraordinary event. Note also the continually expanding body of evidence of terrestrial cratering epochs, each involving multiple impactors).

Tom is theorizing a large scale initial bombardment concentrated on one hemisphere of the planet. I don't know how that would affect water flow terrain distribution. If the exploding planet was "wet" it stands to reason that most water would at least initially end up on one side of Mars. The thing I find attractive about the theory with respect to Martian terrain, is that it explains the apparently huge amounts of water flowing, but flowing for only a short time.

Your description of exapnding Mars theory sounds interesting and plausible. What makes the EPH more compelling is that it ties together so many anomalies in the Solar System, while at the same time making good predictions.

If a planet exploded 3.2 million years ago, creating all the asteroids and comets, wouldn't we expect a fairly significant mass extinction on earth at that time? Far as I can tell, there wasn't one. As the information below indicates, there have been a number of minor extinctions over the past 2.5 million years (beginning 700,000 years after TvF's hypothesized planetary explosion), and these have been attributed to climate change rather than extraterrestial bombardment.

Apparently, 3.2 million years ago on earth, life was good. 8)

__________________
Everyone is entitled to his own opinion, but not his own facts.

I am sure I fell asleep during this thread, but, what is the problem?

Why is it so hard to except mass extinctions on such small time scales?

If the Pres of the USA nuked Russia would there not be a mass extinction if the Russians nuked the Pres Bush back?

Looks like a no-brainer to me.

Yes, you apparently fell asleep, Snowcelt. I was trying to debunk van Flandern's exploding planet hypothesis by pointing out there was no remarkable extinction event during the time vF claims the explosion happened. If a planet exploded 3.2 million years ago, creating all the comets and asteroids, I would venture that there certainly should have been a major mass extinction. But there wasn't.

Some say there is a pretty hefty mass extinction going on as we speak. Not due to climate change or ET bombardment or nuclear idiocy, but due to humans and their oft destructive actions and policies, well exemplified by those of the current U.S. administration.

__________________
Everyone is entitled to his own opinion, but not his own facts.

But none of these are "unexplained", simply or otherwise. In fact, all of them are quite well explained by normal, "mainstream" processes.

The Uranus system is easily explained as the result of a large collision event, during the aggregation of planetesimals into planets. This could also explain the retrograde spin of Venus, though it is even easier to explain that as an effect of momentum exchange between the planet and its atmosphere.

Pluto's orbit is hardly an "oddity". It is locked in a 3:2 resonance with Neptune. Standard celestial mechanics, Tom's forte, explains this straight away, and also explains the eccentricity & inclination (both of which are pumped by the resonance with Neptune).

The idea that asteroids in the asteroid belt might be the remains of a former disrupted planet was indeed considered seriously back in the 50's. But it was abandoned becasue it does not work. Not only do the very different chemical compositions argue against this hypothesis, but so does orbital mechanics. The asteroids are known to come in orbital families, which can be (and have been) traced back to a common point of origin. In short, the idea works on a smaller scale. Several asteroid families are the result of collisional disruption of parent bodies. It would make more sense not to postulate one exploding planet, but rather two colliding planets, although there are still too many orbital families of asteroids to accomodate.

Why are Earth crossing asteroids something that require a bizarre explanation? All of the asteroids (or asteroid parent bodies) are nothing more exotic than the ash heap left over from the era of planet formation. Not all of the planetesimals became planets. Why should there not be orbiting junk left over everywhere?

Perhaps the only real "problem" in the list is the peculiar color of the leading hemisphere of iapetus. But that too is not a significant mystery. Similar, but less obvious coloration is present on Callisto, and on all of the Uranian satellites. The likely cause is dust deposition, the dust coming from the outer, retrograde satellites, and in the case of Iapetus, nitrogren rich organics from Titan's unique atmosphere, will make it darker (the leading hemisphere is always the darker one).

Why is Tom's explanation "better" than this, when it relies on a hypothesis (the "exploding planet"), which has no known physical cause, whereas the standard explanations all rely on well understood & observed processes?

Well, one obvious answer is that an Oort cloud population of comets will produce inner solar system comets on very high inclination orbits, at very long periods. Also see The Kuiper Belt, by Paul R. Weissman, Annual Review of Astronomy and Astrophysics 33: 327-357, 1995, specifically figure 2 on page 336. The observed distribution of orbit inclinations & semi-major axes is compared with the distribution resulting from a dynamical model of a Kuiper belt & Oort cloud. The model very well reproduces the observed distribution. The Oort cloud passes a significant test: It reproduces the observed orbital characteristics.

On the oher hand, an exploding planet does not do a very good job. For one thing, it would produce far too many high inclination orbits and far too few low inclination orbits, compared with observation (unless you assume an arbitrarily asymmetric explosion). Furthermore, an explosion would cook the volatiles (ices) that we know, by dint of direct observation, are the primary constituents of comets. It is, compared to the "mainstream", a poor explanation.

Of course, the fact that nobody (including Tom Van Flandern) has the foggiest notion how to make a planet blow up, surely counts for something in deciding whether or not that hypothesis is better than the mainstram explanation.

To go a bit farther over what Tim just said:

Imagine trillions of rocks, each miles across, all orbiting the Sun. They are distributed evenly, so that essentially all of space has rocks all through it. Imagine too that the only planet in the system is Jupiter. Over time, those asteroids with orbits that crossed Jupiter were either dropped into the Sun or ejected from the solar system (this is what happens over time when they interact with Jupiter's gravity). Over billions of years, any rock with that kind of orbit is gone.

There is also a phenomenon called resonance. This is when the orbit of one object is a simple multiple of another's. A rock that orbits the Sun a bit farther out than Jupiter might have a period twice Jupiter's (24 years, to Jupiter's 12). Every time the rock orbits the Sun, Jupiter orbits twice. To the rock's perspective, it sees Jupiter in the same place every time it orbits the Sun. Jupiter pulls on it every time, so eventually the rock leaves that orbit, moving in toward the Sun. Eventually, its orbit loses the resonance, and it orbits every 23 years, say. Then Jupiter doesn't affect it that way anymore, and the orbit is stable.

Now wait a few billion years, and take a look at the system. You'll be left with rocks on all sorts of orbits inside, say, where Mars would be (but remember there are no inner planets in this imaginary system). You'll have virtually no asteroids from that point out to somewhere a little past Jupiter's orbit, because direct interaction with Jupiter has flung those rocks away.

All the resonance orbits are empty. Nothing with an orbit of 24 years is around. Nothing with 18, either, because that's 1.5 to 1. You get a weird system: lots of rocks close to the Sun, none at all at intermediate distance, and rings of rocks because of the gaps where the resonances are (this is why there are gaps in Saturn's rings; resonances with Saturn's moons clear those spaces out).

But wait! Let's take a closer look at that 1.5 to 1 resonance. Let's say you start with a rock on one side of the Sun, and Jupiter at the other. After one orbit of the rock, Jupiter goes around 1.5 times. It's back on the other side of the Sun. This is still a resonance, but unlike the others, it's a stable one. The rock essentially avoids Jupiter and never gets affected by it. Yes, this is an oversimplification, but it makes the point. A 3:2 resonance is stable.

So if you start off by looking at the system, with its weird distribution of rocks, you might be baffled and inclined to think strange forces were at work. But there aren't. Well, there is just one: gravity, and does sometimes have strange and surprising behavior.

Pluto's orbit is in that 3:2 resonance with Neptune. There is a whole class of objects like that, called Plutinos. Anything near Neptune that doesn't have that kind of orbit would have been tossed away eons ago by Neptune's gravity.

Earth-crossing asteroids can have many explanations. They might have a saving resonance. Or they might be asteroids that had slightly off-beat resonances with Jupiter, and after all this time are just now getting pumped into weird orbits that dip them in closer to the Sun. I am not an expert on this, so I won't go farther. But it is not terribly hard to imagine scenarios explaining all the problems you brought up, Boris, with nothing more extravagant than gravity, and an existing body of asteroids.

This yet another reason (in a long line of them) that I have grave doubts about Tom van Flandern's ideas.

Another thing to remember: a lot of smart people spend a lot of time looking into this stuff. They're not like you and me; they spend all their time thinking about this. If something doesn't work, or seems fishy, they work on it. They wouldn't simply toe the party line because it's the party line. They work out the math and physics of resonant orbits, gaps, orbital migration and the like. And they seem to have no problem with the "mainstream" theory, and serious misgivings about TvF's.

And finally, one more thing to remember: if you come into something like this having started off reading the 'against the mainstream' theory, it is likely to give you a tainted view of the mainstream. It's rather like seeing the Fox show on the Moon Hoax. You might have serious doubts about the Moon landings, until you get the facts. In this case, I think people who start off reading TvF or Arp or Frank or the others start off with a slanted viewpoint, and it's very difficult to rid yourself of that bias. I have worked for years to try to look into alternative theories fairly. If they have merit, I'll stick with them. If they don't, out they go (as was the case with Louis Frank's minicomets; if you peruse the search engine on my site you'll see I was very interested in them early on, but now I understand they don't exist, and Frank is dead wrong).

I've blathered on long enough. I don't know if this helps or not, but hopefully this essay will give you insight on several key points:

1) Some things look weird, but may have simple explanations. Perhaps no far-out theories are needed to explain them when a simple, which we understand pretty well, one will do.

2) It's easy to get biased early on, especially when reading an embittered account.

3) 100 smart people versus 1 smart person doesn't mean that the 1 smart person is wrong, but it should at the very least give you pause.

__________________
Phil Plait
The Bad Astronomer
http://www.badastronomy.com
badastro@badastronomy.com

How many administrators/moderators of any other board can post something like that? Nada, zilch, none .. that's why I like it here 8)

Following up my own remarks, I was writing with little time, based on my memory of a paper I had seen last year. Here is the reference I had in mind.

The recent breakup of an asteroid in the main-belt region
D. Nesvorny, W.F. Bottke, L. Dones & H.F. Levison
Nature 417(6890): 720-722, June 13, 2002
ABSTRACT: The present population of asteroids in the main belt is largely the result of many past collisions (1,2). Ideally, the asteroid fragments resulting from each impact event could help us understand the large-scale collisions that shaped the planets during early epochs (3-5). Most known asteroid fragment families, however, are very old and have therefore undergone significant collisional and dynamical evolution since their formation (6). This evolution has masked the properties of the original collisions. Here we report the discovery of a family of asteroids that formed in a disruption event only 5.8 +/- 0.2 million years ago, and which has subsequently undergone little dynamical and collisional evolution (6,7). We identified 39 fragments, two of which are large and comparable in size (diameters of ~19 and ~14 km), with the remainder exhibiting a continuum of sizes in the range 2-7 km. The low measured ejection velocities suggest that gravitational reaccumulation after a collision may be a common feature of asteroid evolution. Moreover, these data can be used to check numerical models of larger-scale collisions (8).

And another paper published since then.

Disruption of fragmented parent bodies as the origin of asteroid families
P. Michel, W. Benz & D.C. Richardson
Nature 421(6923): 608-611, February 6, 2003
ABSTRACT: Asteroid families are groups of small bodies that share certain orbit (1) and spectral properties (2). More than 20 families have now been identified, each believed to have resulted from the collisional break-up of a large parent body (3) in a regime where gravity controls the outcome of the collision more than the material strength of the rock. The size and velocity distributions of the family members provide important constraints for testing our understanding of the break-up process, but erosion and dynamical diffusion of the orbits over time can erase the original signature of the collision (4,5). The recently identified young Karin family (6) provides a unique opportunity to study a collisional outcome almost unaffected by orbit evolution. Here we report numerical simulations modelling classes of collisions that reproduce the main characteristics of the Karin family. The sensitivity of the outcome of the collision to the internal structure of the parent body allows us to show that the family must have originated from the break-up of a pre-fragmented parent body, and that all large family members formed by the gravitational reaccumulation of smaller bodies. We argue that most of the identified asteroid families are likely to have had a similar history.

There are other papers, but these seem to be the significant ones. We can trace asteroid families back to the parent body, by orbital mechanics, so long as the collision did not happen so long ago as to erase the orbital signature.

If the asteroids were formed by an exploding planet, the fragments of the planet would have rapidly moved away from each other, in approximate spherical symmetry (most likely). Perturbed gravitationally by the sun & planets, those fragments would not likely have come back together again, into a collisional environment. So, the argument that these asteroid families are collisional is an argument in opposition to the idea that they came from a planetary explosion.

Also note that a planetary explosion would not produce orbital families at all. If anything, they would have to be formed in the post explosion environment, either by collisions (already noted as unlikely), or by orbital evolution. But the latter could only come about by resonance, which is also unlikely, because the planet fragments have too much angular momentum, and because they are too widely spread out.

However, in the mainstream argument, we expect a collisional regime, and observation is consistent with that expectation. And I can think of no expectation from mainstream theory that is contradicted by observation.

Having followed up on my own remarks about asteroids, I want to expand my remarks on comets & the Oort cloud, with reference to comments from both Boris & Van Flandern.

First, some comments on the Oort cloud. I will reiterate my earlier point: The Oort cloud model does pass a crucial observational test, in that it properly reproduces the apparent distribution of short & long period comet orbits, in eccentricity & inclination as functions of the semi-major axis.

Now, a comment earlier from Boris:

I maintain that this comment is unacceptably naive. Not only is it not at all "farfetched", it is in fact an absolute necessity of orbital mechanics. It is impossible for the passing star mechanism not to be significant. And, furthermore, I will argue that it has indeed been "observed", even if only mathematically. After all, the relative motion of local stars with respect to the sun is hardly so fast as to allow direct observation of such a slow process. But our inability to see it in real time is of no concern to the scientific validity of the process.

On the web, see "stellar perturbations", a short description of the physical process, from Dave Jewit's Kuiper Belt pages. Oort cloud comets may be as far as 100,000 AU from the sun. That's 1.6 light years, and at that distance, the sun's gravity is in fair competition with the gravity of other stars, as well as the tidal field of the galaxy, which Van Flandern himself blames for smearing out the orbital signature of planetary explosions more than ~10,000,000 years ago. If those tidal forces can smear out inner solar system orbits in that little time, they can certainly smear out orbits 1.6 light years out, in a rather shorter period of time. And this expectation is verified by direct analysis, published in the literature. See, for instance, Characteristics and frequency of weak stellar impulses of the Oort cloud, J.J. Matese & J.J. Lissauer, Icarus, 157(1): 228-240, May, 2002.

The "passing star disturbing the Oort cloud" does, in fact, survive a critical examination. This is not surprising, as there are periodic "close" encounters between the sun and other stars, over long periods of time. Those encounters could hardly be expected to not disturb the Oort cloud (Gleise 710 will pass within 1 light year of the sun in 1,000,000 years, probably passing through the Oort cloud).

This research is found on Van Flandern's webpages: The Exploded Planet Hypothesis – 2000. Scroll about 1/3 of the way down the page, to his figure 2, a plot of semi-major axis vs eccentricity, for main belt asteroids. If there is any "formal", mathematical presentation of the theory anywhere, I can't find it.

But I do find the diagram unconvincing. Van Flandern has drawn a purple "V" shaped line at the bottom of the figure, arguing that it shows the shape of an "avoidance zone", expected if there was a planet explosion, and unexpected if there was not, or so he tells it. I disagree.

For one thing, just see the plot without the "V" and it is immediately evident to the eye that a number of different "V"'s would do just as well. In fact, it appears to me that a flat line, at an eccentricity of ~0.04 or ~0.035 would be equally appropriate, with no "V" at all. But the "V" is needed to indicate the location of the putative exploded planet. No "V", no exploded planet. Since I see nothing in the data that make the "V" anything other than imaginary, then I see nothing in the data that make the planet anything other than imaginary either.

I also find his claim that mainstream theory predicts no avoidance zone as very had to swallow. I would say that there should be a low eccentricity avoidance zone, without an exploding planet, because the eccentricity will be pumped by planetary perturbations (mostly Jupiter, but the other biggies might be involved as well). So I don't follow the logic.

But here is a comment, from the paragraph just above figure 1, that really has me floored.

How about "comets have tails, asteroids don't"? It may not work in absolutely every case (i.e., Chiron), but it surely looks like a "defining characteristic to distinguish one from the other" to me.

Indeed, comets are so different, and so obviously different from asteroids, that I am perplexed. How could Van Flandern say such a thing with a straight face? Comets are systematically smaller & less massive than asteroids, and less dense. One could argue that some asteroids are "used up comets", but they are more likely to turn into meteor streams, and not asteroids.

So, to summarize, I have looked at Van Flandern's webpage and find his arguement weak & unconvincing. I find Boris' critique of the Oort cloud hypothesis equally weak & unconvincing.