Science’s doomsday team vs. the asteroids

[Billy T]

...A simulation where the dark visitor approaches from above yields similar results. In this case, Saturn, Uranus, Neptune & Pluto were ejected, Jupiter was forced into an elliptical orbit with a high inclination. Mercury, Venus, Earth and Mars were virtually unchanged...

Thanks - very interesting - pretty pictures. I wrote simple three-body finite-time-step code in a spread sheet and could not follow full orbit year beyond a few Earth years, but Earths orbit closed very well when code was tested with DV's mass set to zero - graph overlapped so well I could not see the starting point or final points and numerical data fit ellipse well. (Total run time was limited - not enough lines "copied down" in spread sheet and time step was limited to about 4 days max, even though each step was computed twice in same line of code - forces acting at first results for end of time step position were averaged with the forces at the start of time step to get "effective average force" acting during the time step. - I know there are much better ways to increase time step size, but I wanted to keep every thing very simple so my target reader could follow it all. I also wanted to use the spread sheet's automatic graphing capacity.)

My graphs and data for Pluto were thus limited to the begin of its fall towards the sun. I fit ellipse thru two computed points to get Pluto's apogee and perigee -not a very good method, in view of your statements as they don't even exist! I did not actually compute anything for any planets except Pluto and Earth. The entire code, step by step explained, prints in less than three pages of the book' appendix 2 - ridiculous by your standards!

Please keep in mind that I never give the initial conditions used exactly and am not trying to do anything but interest a person not currently interested in science to be come so. I wanted to give a flavor of the method of science, not do any. I set the miss distance to 12AU so I could go into details about gravity gradient ripping Saturn apart, if the timing was such that they got close.

I am glad you confirm that the change in Earth's orbit is very slight. Can you easily extract the new eccentricity? How does it compare to my 0.0836? I can't be sure, because of the perspective in your figures, but looks like from the curvature of the purple dark visitor line that your 2.2 mass is going significantly slower than mine, so I expect that even though you don't see much effect on Earth, your computed change in eccentricity is greater. My dark visitor is initially taking approximately 10 days to close on the sun by 1AU. What speed did you assume (before solar acceleration is significant)? I am nearly at a speed where the "impulse approach" is meaningful. For reasons I will not go into here, but will tell in private msg, I can't give its absolute speed relative to "fixed stars" or sun's initial position.

Again thanks - BTW I have read (and repeated here) that even the solar system is chaotic. How far into the future does one need to go to see an object in it signficantly change its orbit, or does that never happen unless a few of the larger asteroids (orbit crossing bodies) are included?

 

[tony873004]

Orbital elements and perihelion and apihelion values are given by the program's menu View >Orbital Elements box. The Earth is virtually unchanged, its eccentricity being about 0.016 both before and after Dark Visitor passed through. Its perihelion / aphelion distances both before and after are 147000000 / 151000000.

But there countless ways you could set up the starting conditions. An object that passes 12 AU from the Earth can pass anywhere between 10 - 13 AU from the Sun depending on Earth's position during the close encounter. I would tend to think that your new figure of 0.0836 is a bit high, but it would be necessary to run the simulation many times with many different starting conditions to rule it out. You can try it youself ( www.gravitysimulator.com ). Send me an e-mail if you need help with starting conditions.

Making DV pass closer to the Sun and not so close to Earth would yield large changes to all the planets' orbits, regardless of their starting positions, as the Sun is yanked from its position.

I ran a few different "in-plane" simulations with different starting conditions and got different results such as which planets were ejected, etc. but the common theme was that the inner solar system (mercury - earth) was left alone, while Mars was affected, and Jupiter and beyond were greatly affected.

In the particular simulation in the pictures, DV's closet pass to Earth was 9.8 AU, slightly closer than your 12 AU simulation. It's just hard to exactly nail down the starting conditions for a perfect 12 AU pass.

Dark Visitor's solar velocity at infinity =~27km/s

The solar system is chaotic, but the chaos tends to show up in the smaller details. For example, it would be difficult to predict where Earth will be in 1,000,000 years. It's eccentricity is going through small periodic changes. So are its inclination, Semi-major axis, period, etc. But on a larger scale, it is safe to say that the Earth will still be orbiting the Sun at 1 AU +- a very small tolarance in an orbit that is close to circular, and close to the plane of the other planets, even though we don't know where in its orbit it will be. It could be on the other side of the Sun compared to where a prediction would place it, which is a huge change in position of about 2 AU. But the size and shape of the orbit won't change that much.

The same is true for all the planets. A billion years from now, it would be impossible to say where the planets will be, but the sizes and shape of the orbits will be very similar to what they are today.

Asteroids have insignificant effects on the size and shapes of the planets' orbits. But they will introduce chaos that will make it impossible to predict the exact locations of the planets in millions of years. It's like the butterfly effect.

 

[misskitty]

Technically, they are not meteorites unless they hit the ground, and it takes a fair sized chunk to do that. Most of what you see in meteor showers are no bigger than a grain of sand.

They are that small! If they are so tiny why do they make the bright streeks you see in the sky? Wouldn't they burn up in the atmosphere so quickly you wouldn't see them?

 

[tony873004]

They're moving very fast and have a lot of kinetic energy. Kinetic energy is 1/2 * mass * velocity^2. So velocity is much more important than mass. They make bright streaks because they ionize the air as they wizz through it.

 

[chroot]

Thanks - very interesting - pretty pictures. I wrote simple three-body finite-time-step code in a spread sheet and could not follow full orbit year beyond a few Earth years

So what you're basically saying is that you wrote a crappy program with a number of essentially crippling limitations, and then went on to write a crappy book about the "data."

I wanted to give a flavor of the method of science, not do any.

Well, that seems like an incredibly stupid way to teach people. I don't suppose you can describe any demonstrated advantages to your "teach-by-stupidity" pedagogy?

We've already talked about this to great extent, Billy T. It should have already been clear to you, but I'll say it again; if you ever, ever make another post on this site about black holes or dark visitors or any other such nonsense, I personally guarantee that you will never be permitted to post here again. Consider yourself thoroughly, inexorably debunked.

- Warren

 

[Billy T]

So what you're basically saying is that you wrote a crappy program with a number of essentially crippling limitations, and then went on to write a crappy book about the "data."

Well, that seems like an incredibly stupid way to teach people. I don't suppose you can describe any demonstrated advantages to your "teach-by-stupidity" pedagogy?

We've already talked about this to great extent, Billy T. It should have already been clear to you, but I'll say it again; if you ever, ever make another post on this site about black holes or dark visitors or any other such nonsense, I personally guarantee that you will never be permitted to post here again. Consider yourself thoroughly, inexorably debunked.

- Warren

I assume I am allowed to respond to you.

About the "crappy program":
It is a simple spread sheet program, fully explained step by step, as my target reader is not a scientist - quite the contrary, he/she is not even interested in science, but probably does use a spread sheet often for financial analysis, etc. I wanted something that he/she could easily do, and play around with.

As far as it being a "crappy program" it is not - it got the same results for Earth (small perturbation)that Tony873004's very powerful program got, but that program probably took many people years to perfect and would never tempt my target reader to try to install it on his PC.

Before we call it "crappy," let's wait for Tony873004 to tell quantitatively how his sophisticated result compare with my "crappy numbers" (e= 0.0836, apogee = 1.108AU, perigee =0.937AU from an assumed circular start at R = 1AU) if he is so inclined. The 2.2 solar mass object misses Earth by 12AU and passing approximately perpendicularly thru ecliptic from a distant starting point with initial sun closing speed of 0.1AU/day.

Your calling it "crappy" does not make it so. It is very well designed program for its purpose - trying to interest people not currently interested in science to become so. If Tony873004 demonstrates that the results are "crappy" that is different, not just an opinion conflict. I will wait for his results, (or from anyone else with access to a sophisticated model)

 

[chroot]

If your intent was to coax people into developing an interest in science, why are you beginning with such an inane premise, a premise that you admitted to me in PM was "highly improbable?" It isn't science. You don't teach people to play the violin by talking about astrology.

The problem I have with you, Billy T, is not that you're introducing the reader with elementary models, or describing an elementary tool. The problem I have is that you yourself seem to have actually trust the data from that elementary tool, which you know is incredibly simplistic, unreviewed, and apparently quite limited, and drawn crazy conclusions from it. You seem to trust this data well enough to write an entire book on the "results."

If your book was full of admissions that the model was too simple, or that the program was inaccurate -- full of urgings that the reader should not take the results seriously -- then I would probably treat you a little more amicably. As it stands, your book disgusts me.

- Warren

 

[Billy T]

I assume I am allowed to answer your questions, even when they are about the book.

If your intent was to coax people into developing an interest in science, why are you beginning with such an inane premise, a premise that you admitted to me in PM was "highly improbable?" It isn't science. You don't teach people to play the violin by talking about astrology. ...

There is a difference between "inane" and "improbable." I certainly admit the plot is the latter, and have done so several times publicly here at PF. One can not teach the violin to a kid with no interest in it. The target reader has no current interest in science. There are already hundreds of good standard approach science books, on all levels, available but my target reader never opens one. Adding one more to the collection would be "inane."

I was forced to try something not as standard as you would like. I toyed with idea of making trying to make it steamy (sex) but then hit upon the idea of an astronomer explaining things to his historian friend about a coming global disaster and using the history of the discovey of Pluto a part of the basis of the story. Orsen Wells got quite a strong response by scaring people, and I though following the path he charted would be better ( I did not entirely abandon the the first approach - the title of the student newspaper article about why it might be true was "A black hole is coming for you" and the vulgar interpretation would surely occur to many students. See full article at my website and try to appreciated how much valid science I squeezed into that short article, after I got the reader's interest with the headline.

I am sorry if my approach gives you a "problem" and the book "disgusts you." Have you read any of it, prior to this judgement? You can read for free (instructions at www.DarkVisitor.com) - I always mention that in every post that refers to my book and do not want this post to be an exception, even if you remove my posting privilege for telling how to read for free.

You have raised my warning level to 14 and repeated told me I am full of crap etc. Could you give one specific example of a false statement I have made here? I have corrected a couple of your posts and you were kind enough to thank me once for doing so. I have had several people thank me for helping them (One even sent me *penny drop* with his thanks and that was first time I have seen this.)

I have also offended some others with my insistence that transformers do not make the secondary current by "magnetic field lines cutting thru the secondary coils" (I mention this because I hope you will think twice before citing this as an example of a statement of mine in conflict with physical facts.)

I have offend others by noting that the two common explanations of Hawking Radiation contradict each other and thus are only "feel good words" (The "hot radiator because of all the swallowed entropy" explanation adds new energy to the universe outside the event horizon as escaping gamma rays and the "half a virtual particle pair escaping" explanation adds the same energy to outside universe as a particle. - this clear mutual contradiction precludes at least one of them from being correct. Is it not OK to point things like this out?)

I would really like you give at least one specific example of my posting "crap."

 

[matt.o]

can this be done over pm please? I am sick of every thread being ruined by some pointless argument over "Dark Visitor" and Hawking radiation.

 

[tony873004]

Billy, without running numerous simulations I can't rule out your figure of 0.0836, but nothing I've tried yet has even come close. Earth seem to be virtually unaffected regardless of the starting conditions. A closer passage distance could certainly give you 0.0836.

The program I use wasn't written by many people over years. It was written by me. I'm just a hobbiest making his best effort. The program uses first order equations of motion to propogate initial starting conditions for solar system objects supplied by JPL NASA's Horizons system.
(ie it puts the formulas acc=GM/d^2, vel = vel + acc, and pos = pos + vel, in a big endless loop with pretty good results.)

Hope this helps.

 

[russ_watters]

They are that small! If they are so tiny why do they make the bright streeks you see in the sky? Wouldn't they burn up in the atmosphere so quickly you wouldn't see them?

Well, it takes about 2 seconds for them to burn up - just long enough for you to see them.

There are occasionally larger meteors that are visible for much longer - sometimes for minutes. Check out this pic: http://www.space.com/scienceastronomy/leonids_commentary_011116.html (click the top one on the right for a large version)

Also has some good info on meteors and fireballs.

 

[Nereid]

If a massive object were responsible for the 1920s observed positions of Neptune (and more?), where would it be now? To what extent would the 'signature' of such a visitor be detectable in the orbits of EKB and scattered disk objects (collected over the last ~50 years)? What sort of wake would a ~solar-mass object (esp a BH) leave in the local ISM? What regions of parameter space can be 'ruled out' by the accurate orbits of the Pioneers, Voyagers, (others)?

IIRC, back when Nemesis was touted as a possible ultimate cause of the (then thought likely) ~20 million year periodicity signal in the 'mass extinction record', a lot of work was done to find where any massive object could be lurking - out to a few hundred au. None were found.

 

[turbo]

If a massive object were responsible for the 1920s observed positions of Neptune (and more?), where would it be now? To what extent would the 'signature' of such a visitor be detectable in the orbits of EKB and scattered disk objects (collected over the last ~50 years)? What sort of wake would a ~solar-mass object (esp a BH) leave in the local ISM? What regions of parameter space can be 'ruled out' by the accurate orbits of the Pioneers, Voyagers, (others)?

IIRC, back when Nemesis was touted as a possible ultimate cause of the (then thought likely) ~20 million year periodicity signal in the 'mass extinction record', a lot of work was done to find where any massive object could be lurking - out to a few hundred au. None were found.

Hi, Nereid!
I don't want to be characterized as a supporter of Billy T's views, but if there was a massive black hole slinging around out there, how do you think we would have been able to detect it apart from some transient lensing effects?

 

[Phobos]

can this be done over pm please?

An excellent idea. I'm closing up this highjacked topic.