[chimera]

We just have a standard formula, and out rolls a size, but we do not have any visual confirmation of exact size, or the size of the accretion disk - several formulas for that, even -, and even those impressive lighthouse beams. All artists impressions are just that, without their incredible effects on their environment, making those at least visible, we wouldn't even know they were there... for a infinitesimal speck on the horizon, they have quite a 'drag'.

Oh and don't be impressed with a bit of google magic: here's the formula for the radius of a black hole (half of its diameter)

(2 * G * ((billions of solar masses * (10^9)) * (1.9891 * ((10^30) kg)))) / (c^2) in lightyears

(just cut and paste it into the google bar, and replace 'billions of solar masses' with any number) where google already knows what you mean with G and c, and can of course do it in  kilometers as well as lightyears or whatever measure you need. The rest of the formula are just pretty well known constants and values.

So fill in a 1000, and you have a pretty precise number for the black hole at the centre of this universe. Hope that makes you try out more stuff with it, it can be pretty awesome.

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[rosy]

Yeah... to be honest I'm less impressed than, um, sceptical... infact now I've checked I'm outright disbelieving.
you have a precise number, but I don't believe you have an accurate number.
According to this website (the people who build NASA satelites, apparently)
http://ssd.jpl.nasa.gov/astro_constants.html
G is only known to an accuracy of 4-5 sig fig and so any calculations based on G will have an ABSOLUTE MAXIMUM accuracy of 4 SF depending on the accuracy of the other values you've plugged in. In this instance, you're using a mass accurate to 1-2 sig fig.
G = 6.67259 (± 0.00030) x 10-11 kg-1 m3 s-2

Given that I know you're rightly keen on questioning everything, it's proabably worthwhile to think twice bfore copy-pasting out of a calculator

[chimera]

That's the spirit. It is the official formula tho, not googles or HP's... r = 2GM/c^2.

here's the different ones for the accretion disk:
http://scienceworld.wolfram.com/physics/AccretionDisk.html

Also M is taken here as 1,9891 and is mostly given as 1,989

http://en.wikipedia.org/wiki/Solar_mass

so yes, it depends on what you toss in, and you might as well cut off the last few million kilometers. If you look carefully at that table you used btw, and scroll to the mass estimates for the solar system, you'll see that the bigger the mass, the more confident the estimate.

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[rosy]

Sorry... I'm not questioning that it's the official (and *presumably* most rigorously tested) formula!
All I meant was that the last few sig figs were pretty much meaningless (except possibly for misleading the unwary as to how accurately it's currently possible to measure this stuff).

[chimera]

Good point. It's only the official, surviving one in a sense, though. There have been others, slightly different, and rejected for different reasons. And testing, ah, testing. Now there's a good point. []

Also all those nice round rough estimates (1000 billion solar masses, why not 956), the fact some of these objects are hundreds of millions of lightyears away and we are roughly estimating all those 'facts' based on observations of disturbances of much greater regions, and it is obvious that this kind of precision would not get you to the moon and back.

But people eat it like pie, and what's worse, they NEED that kind of semi-certainty, as if it made some kind of a difference.

(Even if my calculation about comparative size at a lighyear was trillions of times off, say the thing would be as big as a pea at one lightyear, would it make any difference? Not much in this case, for all practical purposes, but next time as for my calculation, too.

Even scientists fall for it. Their need to appear so confident and infinitely precise is just filling in a niche, and of course they oblige. They can fulfill the same kind of psychological need for *reassurance* in our knowledge as priests do, and not only purely in our *knowledge*.

Therefore scientists should always be aware of the important difference, and Joe and Jane Public a lot less demure in his or her questioning.

added:

an example of such an article that I hope people will now read differently than before:

http://www.obspm.fr/messier/more/m087_hst.html

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[daveshorts]

I think Rosy is making a far more fundamental point, which was drummed into me in Physics A-level and during my degree...
"If you put rubbish into a formula you get rubbish out" so if you are putting figures in that are +/- 30%, the answer will be (depending on the exact formula) +/- 30%, so quoting the answer to .00000001% is pointless and very misleading.

[chimera]

Mmm. Where'd you get that 30% from? My calculations were deceptively precise, but not off by more than a relative whisker, certainly not that.

Calling an object 'solar system sized', or pretending that it is any kind of exact measure, now that's misleading. What kind of definition is that?

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[daveshorts]

I was talking in more general terms, but you are picking an arbitrary mass of about 1000 billion solar masses surely it is not meaningful to quote the answer to more than 1-2 significant figures?

I am not saying that there is anything wrong with your calculation, just that you are quoting the answer to a ridiculous accuracy... possibly a bit picky but you did start it

[chimera]

The difference in G is a max of 30 per 10,000, that's the closest I can think of. Anyway.

Using more than 2 decimal places in these matters is not what it's about, though. Remember the name of the thread? It's about gullibility more than anything else.

I didn't pick the number of 1 billion

• solar masses, or 3 billion. Those are numbers used in documents by scientists. Why these? Probably because it is a nice round percent of the weigth of your average galaxy, and gravitational disturbances are more likely to be measured in those terms. 'We have a 3-percent mass disturbance here', like.

Fact remains, that ANY direct mention of such sizes, has very little to do with direct observation, but are derived via yet another calculation/guesstimate. Fact number two remains, tho: the sizes mentioned are not only questionable, but if they are anything, they are too big. In that sense the calculations are very valid and not misleading.

Which leads us back to my original proposition that dogma has its counterpart in pulp science, where the need for reassurance wins on factuality/inquisitiveness by a knock-out.


[* edit late typo - that was what the whole argument was about: you cannot have objects that need 1000 billion or 3000 billion, like a 1/2 - lightyear-big black hole - sorry for the late edit but I had to leave in a rush and realised it only later, I'll stick to exponential notation in future, sigh.]

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[chimera]

quote:Originally posted by daveshorts

I was talking in more general terms, but you are picking an arbitrary mass of about 1000 billion solar masses surely it is not meaningful to quote the answer to more than 1-2 significant figures?

I am not saying that there is anything wrong with your calculation, just that you are quoting the answer to a ridiculous accuracy... possibly a bit picky but you did start it

Summarising:
Dave, with rosy's comments calculated in, there would be only a marginal difference between my answers and the ones that would be used in an official paper, where cutting off at a certain decimal is more of an editorial function, or adding a +/- uncertainty to avoid any nitpickery.

Again, because of the numbers used, this would be millions of kilometers different in reality, but as for the calculation still be more in the order of 1/30th of a procent, than 30.

Also don't forget that the calculation is done in kilometers, before converting to lightyears. That's only done in the end, of course.

As to your question about sizes of suspected accretion disks:

"This 130 light-year diameter disk encircles a suspected black hole which may be one billion times the mass of our Sun."

http://bustard.phys.nd.edu/Phys171/lectures/smbh.html

so you can work out how large the object would have to be according to the accretion disk formula, and see for yourself it cannot correspond to an object weighing only 10^9 kg, especially not it if the objects's lightyears across.

[daveshorts]

We are not critising your calculation, just how accurate it is worth quoting the answer. 30% as I said earlier was just a number picked out of the air with no particular relevance to your calculation to make a point. However if you are going to be awkward I will:

You may be correct if you actually meant to calculate the schwartzchild radius of a black hole of mass 1billion +/- 1 solar mass - but I don't think there is any point unless you are considering building the black hole. I think what you meant was about 1 billion solar masses - in which case the implied precision is 1-2 sig fig, so although you may be technically correct, there is still no point in quoting so much precision.

If you read http://bustard.phys.nd.edu/Phys171/lectures/smbh.html carefully the 130 light year thing may be feeding into a smaller inner acretian disk - I would guess that the outer disk is not in hydrostatic equilibrium, and therefore doesn't fit with your equation. It is therefore not stable but I don't see why there should be a maximum size of a cloud of gas and dust that is gently falling into a black hole- I am not sure what the exact semantics are, but I would guess the problem is in the definition of accretian disk rather than the physics.

[chimera]

I'm sorry, but that's not the same kind of caveat's I'm reading from those texts, but instead only roaring enthusiasm - make that cock-certainty - for something that MUST be a black hole, cannot be something else, whatever the slight (!) differences with observational data.

So, suddenly its not strictly 'allowed' to use a math formula given by physicists as their best effort at calculating mass and size of a black hole, because we have to make allowances for all kinds of uncertainties and possible varations on a theme.

OK, fine by me, as long as we all know our place, I guess.

Funny how if someone postulates something more common than a black hole, like a variation on a neutron star, all hands are called on deck to burn heretics using the same formulas, in essence. Did you know the word heretic originally simply meant 'doubter', btw?

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[daveshorts]

relax, I am not complaining about your calculation just making a picky, but quite fundamental, point about how you should present the result...  

ps can I please not be on board the ship that burns heritics aboard - I find building fires somewhere less flamable ob balance a little better

[chimera]

There's nothing fundamental in blowing up a supposed error by a order of 4, it's just erroneous, and your tenacity about it is honestly getting a bit tedious by now. If you did not mean to say it, or meant anything else, why react at all? Could have saved yourself the whole thing.

I really wish you were so tenacious about seeing the the importance of a difference between observation and theory when it concerns a difference of an order of 3, a 1000 times,  as observed, instead of going on about something maybe differing at 4 digits behind the comma.

One thing they even acknowledged in the bible, something with a mote in the other's eye  while missing out on the beam in your own.

This is not some political debate where it's your taken position that decides your acceptance of facts and figures or negative polls or not, it's science. Dammit.

Oh, I like to do my heretic-burning preferably aboard oil-tankers filled with the best high-octane stuff, btw. And then take the chopper out. What you take me for, barbaric?  []

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[rosy]

Oh honestly people.

Rob, if you're bored with this discussion no-one's making you take part.

Dave is making an entirely valid point. The correct use of precision and error analysis *is* in general terms very important, and not at all the editorial decision Rob dimisses it as being.

The error quoted is a measure of the author's confidence in the results and to quote any calculation to 9sf is to imply that you are absolutely confident that (assuming your theory is correct) the value of whatever you've calculated is correct to 0.000001% (or thereabouts). Which is obviously not the case in this context.

Clearly this doesn't really apply to a discussion forum when we all know you've copied and pasted out of a calculator and perhaps in this context my small mickey-taking was a bit childish.

quote:I really wish you were so tenacious about seeing the the importance of a difference between observation and theory when it concerns a difference of an order of 3, a 1000 times, as observed, instead of going on about something maybe differing at 4 digits behind the comma.

Just as a matter of interest (and because if you've already said further up the thread I can't find it) where are you quoting this famous supposed-black-hole from? A research paper? A popular science magazine? A newspaper? A random person's website? I can't work out how bothered I should be...
If this comes from a supposedly reputable source someone apparently deserves to lose their job. If not, well, to be honest I can't get all that excited about people accepting it as probably true, because to expect most people to have any concept of the physical implications of anything that big strikes me as frankly silly. That's not to say I'd apply the same logic to a comparable mistake in a field such as chemistry or biology because an equivalent mistake could in that instance influence the decision of John or Jane Public on something that was actually relevant to their lives.

quote:Oh, I like to do my heretic-burning preferably aboard oil-tankers filled with the best high-octane stuff, btw. And then take the chopper out. What you take me for, barbaric?

Eh? I thought you were suggesting you were the heretic, in which case surely once someone's lit the bonfire what it sets fire to (other than yourself) is of purely academic interest to the doubter.

[chimera]

quote:Originally posted by rosy

Oh honestly people.

Rob, if you're bored with this discussion no-one's making you take part.

Clearly this doesn't really apply to a discussion forum when we all know you've copied and pasted out of a calculator and perhaps in this context my small mickey-taking was a bit childish.

I can't work out how bothered I should be...

If not, well, to be honest I can't get all that excited ....

Eh? I thought you were suggesting...

Maybe you should make fewer assumptions, be less bothered, and not get all that excited, then?

If you have any questions as to the material discussed, read again.

Furthermore, I'd say Dave is perfectly capable of answering for himself, don't you think?

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[rosy]

quote:Furthermore, I'd say Dave is perfectly capable of answering for himself, don't you think?

More than capable. However, if I choose to make a point in an open discussion and to observe in passing that mainly what I'm saying is in agreement with someone who's just posted that strikes me as fair enough.

quote:Maybe you should make fewer assumptions, be less bothered, and not get all that excited, then?

I think possibly you didn't understand my question. Or misinterpret how aggressive I'm not intending to be. Or you're just being rude. I can't tell (the disagvantages of a text forum).
It was a question, where did the original erroneous statement about the black hole come from? Because it seems to me relevant in terms of to what extent it's reasonable to describe it as scientific dogma, which was your original point. And having scanned the thread for links again I still can't find it.

However. As I've only stuck with it this far because I was trying to work out whether I agreed with your basic point or not, and as I'm not nearer an answer and seem to have annoyed you, I shan't pose any further questions and will merely apologise for taking up your time.

[chimera]

Look, I'm butting out of this thread after this remark, so don't bother any further:

I said:

quote:
Anyway: nice experiment to show how even scientists can fall for dogma: any scientist willing to conduct it with me by answering the following question:

A black hole has been reported sitting at the center of a galaxy close to 450 million lighyears away, and it has a size calculated to be around 3,5 to 5 lightyears in diameter.

Yet, there is something totally impossibly wrong with it. Something that defies our astronomic common sense.

Now, what question would a respectable scientist - being impervious to dogma - ask first, before investigating the matter any further?

So this is clearly no reference to a direct article, but an example of what I called 'pulp science', as in 'spot the loony' for a self-respecting scientist kind of 'exam' to see if you smelled a rat somewhere.

Later I DID give two links with two reports that are of that ilk , more or less. One speaks of a 'solar system size' black hole of a billion solar masses which I find rubbish, and another that claimed a 130 lightyear accretion disk, which hides an equal improbable element, but less clearly so, or with a lot of unstated provisos. More accurate numbers would be 3.6 million for the one at our galaxy, with an outer accretion disk of 15.3 lightyears, give or take a trillion miles.

The calculation boiled down to 8.86109896 × 10^09 kilometers, and depending on where you cut off (2, 4 or no decimals cut off) it becomes 0.000936522742, 0.000936628444, or 0.000936638904 lightyear as I gave earlier. Take your pick, nothing much changes.

So you misread an experiment showing how people can get carried away following dogma, as an real article, missed the real articles tho, made a valid point about precision, which David hastily misread in all likelihood - on rereading-  and from there the whole thing degraded into a discussion strictly about supermassive black holes and burning heretics.

The funny thing is I don't believe in either, btw. But if you do something, do it well.

'Misinterpreting how agressive I'm not intending to be' gets the QT award 2005, tho.

On telling emotions from text-only forums: think how a blacksmith tests for quality in his steel  by making a clear spark fly off it. That speaks volumes to the trained eye, as long as the spark does not end up in said eye, ofcourse. []

The living are the dead on holiday.  -- Maurice de Maeterlinck (1862-1949)

[Tronix (OP)]

Well, maybe i should check this thread more often

As sharp as the argument was, the debate over the plausibility of such a huge black hole did bring up another point about science and religion.

Chimera here was proposing that a black hole of this size is impossible, with Mathematics to prove it. Christians, when debating the divinity of Jesus, also look to the bible and its tales of his miraculous actions to prove his divinity. But, in both cases, physcial observation cannot be used. Jesus is 2000 years dead, and should a black hole of that size exsist, we have yet to find, or be aware, of it. Thus, nothing completly concrete, but regardless, heated debates.

And there even seems, ever so slightly, that there is dogma in science. chimera made an excellent point with his hypothesis for his social experiment, the "pulp science" dogma.

Now, keep in mind when i say dogam, i mean webster's definition of dogma being "tenets, beliefs, and/or doctrines, collectively". Dogma has a negative connotation, but since i dont want to beat around it, im just mentioning this now. I think the defintion of dogma we are used to is "an positve, arrogant assertion of opinion" defintion. This is not the one i mean.  

returning to point, the pulp dogma chimera pointed out was the acceptance of fully wild phenomenon as plausible, merely out of ignorance, and that Joe Schmo's average exposure to science is through Lara Croft, Star Wars, and a few high school classes that he quickly forgot. In deed, this can happen, and does. From my own observation, im seem to be quite a victim to it, drawn to the possiblity that science can bring, not watching for and even avioding its borders.

but also, i think there is the other end of that dogma, a sort of "Mathmatical Evangelicalism". The laws of physics, paticularly the laws of Quantum Physics, are treading on brittle ground, for that they are logic based on finite observation. Numbers like pi were and are based on physical circumstances here in our world, and alot of our astrnomical knowledge is based on telescope observations. The accuarcy of mathematics is astounding, but being based on finite constants, it has only so many possible outputs. Thus, we have impossiblities in our science, and should it turn out that these things ARE possible, reams of mathematical text would have to be recalled and burned, which would maen the life's works of hundreds of living mathmaticians would be for not. Chimera, with no offense intened, seems to be following this set of beliefs. Thus no one is immune to dogma, at least not until they realize it. Still, how would one define his/her world without seperating what is possible for what is not, or at least is entirely unlikely.

my point is again that religion and science has similarities, including beliefs to defend, and (not to beat this to death), faith to give strength to that defense, and even logic and reasons to defend them with.

Post on in piece my friends. Im mean pieces, I MEAN PEACE!    


--------------------------------------------
"If i cannot have company whose minds are clearly free, I would prefer to go alone."                  -Dr. Gideon Lincecum

The BPRD rejected my application becuase their brain-controled by Cthulhu Rip-offs. And im sure "Sparky" is sleeping with them too, kinky little firecracker she is...

[chimera]

quote:Originally posted by Tronix
Chimera, with no offense intened, seems to be following this set of beliefs.

No offence taken, altho I only believe what I see, and sometimes not even that. Any rules of thumb resulting from that are my own, and I would not even try to impose those on others, since I could not even begin to formulate them. There are no permanent good answers in my book, only recurring good questions.

It seems indeed to be the case that mathematical abstraction has been taken quite a bit too far, with desastrous results looming both for science and our little human collective. Turning that back, or burning the results, as you seem to fear, is not on my agenda.

Finding a way to create a bridge between what goes under the guise of 'common sense' and those possibly inappropriately applied 'infinity'-based solutions, is. I know that sounds pretty quixotic, but Dutch just have this wind-mill hangup, so please indulge me.

OT:

Think on the other hand of the dangers of a runaway belief system applied to the blessings of science, unchecked. It might be okidoki as long as everything is on the up, but as soon as serious disaster occurs, people in the past not only blamed their 'priests', but occasionally inflicted grievous bodily harm upon them, too.

So if Joe Schmoe ever get seriously 'disappointed' with some break-away avian flu disaster, or Hawking retracting everything he's ever claimed to know, things like that, real faith-breakers or stuff scientists could be actually blamed for, be very wary of the possible outcome. You're having it good, very, very good.

Mussolini never imagined those same cheering crowds to simply hang his dead and charred body upside down from a lamppost, either, after a similar disastrous job evaluation session.

Getting 'fired' would be the least of your worries. So keeping your customers' expectations as to your product performance a bit realistic is in your own long-term interest, I think. And also realism about your own role in this. If it walks like a priest, talks like a priest etc, so don't think you can then suddenly renege on any such behaviour - breaking the unwritten contract - it will only be considered aggravating circumstance at payback time. People have a violent hate for false prophets, remember.

And whether you agree with that epithet or not will be quite immaterial by that time.

[hey, summer's breaking out here - off to the lakes for some serious melanine experimenting, you guys have fun too...][8D]

[typo]