Andromeda to collide with Milky Way in ~4 billion years

[Dowly]

May 31, 2012: NASA astronomers say they can now predict with certainty
the next major cosmic event to affect our galaxy, sun, and solar system: the
titanic collision of our Milky Way galaxy with the neighboring Andromeda
galaxy.

http://science.nasa.gov/science-news/science-at-nasa/2012/31may_andromeda/

Bring it on! :arrgh!:

[CaptainMattJ.]

http://www.subsim.com/radioroom/showthread.php?p=1891913

[mookiemookie]

Want to be depressed? Read the timeline of the far future:

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

7.9 Billion years: The Sun reaches the tip of the red giant branch, achieving its maximum radius of 256 times the present day value.[36] In the process, Mercury, Venus and possibly Earth are destroyed.[38]

[Blacklight]

Also, by then , Earth's orbit may be crazy as well. It's VERY hard for a planet to stay in a perfectly stable orbit. Over time, small perturbations in the Earth's orbit might add up and throw us into a radically different apocalyptic orbit. Frankly, it's amazing that Earth has stayed in this relatively stable orbit THIS long. Most planetary systems end up with really eccentric orbiting planets.

[Agiel7]

However, given the astronomic distances between celestial bodies, the chances that a given object will collide with another (a planet, star, etc) in the Milky Way/Andromeda merge are an extremely tiny fraction of a percentage.

[Skybird]

Also, by then , Earth's orbit may be crazy as well. It's VERY hard for a planet to stay in a perfectly stable orbit. Over time, small perturbations in the Earth's orbit might add up and throw us into a radically different apocalyptic orbit.

I think it works exactly the other way around. Small oddities in orbit over time level out. Even big ones, as the scientific model of how solar systems accrete tiny pieces into bigger rocks and finally into big clusters that then form out as even spheres and finally planets. From a wild party with millions and millions of carambolages to a relatively tidy place with few objects revolving in elliptic orbits around the sun that at first glance appear to be round circles. The forces that may occasionally work against the established "gravitational structure" of the solar system and one of its objects may be exixstent, but are so small that they are of theoretical value only. For example the net effect often mentioned solar winds "pushing" against the moon per year accumulate to an eqivalent of the force of four tennis balls being thrown against the moon. Now imagine how many balls you need to throw before the moon changes it'S orbit, and consider that the moon is subject to a much stronger player as well: Earth'S gravitation that has even stopped it to revolve around its own axis independently (that'S why the moon shows us always the same side, no matter where it is located around Earth).

It would need the impact of a very huge stellar object colliding with a planet to make it changing its orbit. And I do not mean a 2 km meteor only, I mean HUGE. Can happen, but is not what you had on mind when saying that small perturbations may add up in total effect to change orbits.

So the fate of moonbase Alpha-1 in 1999 will probably never meet us. :D

[U570]

Want to be depressed? Read the timeline of the far future:

http://en.wikipedia.org/wiki/Timeline_of_the_far_future
or even more depressed? In the year 10^10^10^10^10^1.1, the chaos theory becomes a reality, and a supermassive blackhole with the mass of the universe will reverse the Big Bang into the Extremely Quick Suck

[kraznyi_oktjabr]

or even more depressed? In the year 10^10^10^10^10^1.1, the chaos theory becomes a reality, and a supermassive blackhole with the mass of the universe will reverse the Big Bang into the Extremely Quick SuckIt would definately be interesting to witness that... :hmmm: most likely not very comfortable though.

[Dowly]

http://www.subsim.com/radioroom/showthread.php?p=1891913

Ah, only searched for 'Andromeda'. :oops:

[Skybird]

or even more depressed? In the year 10^10^10^10^10^1.1, the chaos theory becomes a reality, and a supermassive blackhole with the mass of the universe will reverse the Big Bang into the Extremely Quick Suck
Remember that science does not formulate absolute certainties, but theories only. Well-founded and lasting theories they become only by the knowledge of the time in which they get founded.

In the end, our perception of the universe around us, is just inside our heads. In some years alrerady, I will be gone. So why should I feel effected and depressed by somethign happening in several billion years - or not? The mosquito I slap with my hand does not care for me killing it. So we must not feel depressed over the future of the universe.

Marvelling the many wonders we can see, is good enough. ;) One look through a telescope or microscope beats the sight of a burning bush in the desert or a glimpse into a crystal orb any time!

[August]

One look through a telescope or microscope beats the sight of a burning bush in the desert or a glimpse into a crystal orb any time!

Not if something looks back from that bush or orb. :yep:

[Dowly]

Not if something looks back from that bush or orb. :yep:

http://i1183.photobucket.com/albums/x462/Dowly/mystaceus.jpg?t=1338899393

[August]

scary spider

I hate to break into that fantasy world you live in but spiders aren't bushes or magic orbs. It does however sound like a cool place to check out. Can I come visit you someday when I need a break from reality? :DL

[Dowly]

Find your own special happy place! :-?

[Skybird]

There is a (true!) news story from India that would make a nice screenplay for a horror movie. A village there has been invaded by a claimed new species of spiders that are huge, unusually aggressive, and lethal. More than a dozen people got attacked and bitten, two died. The government has used chemicals in large quantities in and around the village. They have sent dead spiders to institutes around the world to have them helping in identification.

The spiders are half as big as a hand palm. And as said: very aggressive and obviously lethal.

It seems they have had a decently sized panic in that place.

Where is Hollywood when you really need it?

[TLAM Strike]

I'm sure someone is already working on a solution:

Someone needs to inform Starfleet. We need subspace field generators, lots of them.
http://img98.imageshack.us/img98/3889/chrysalis188.jpg

Also, by then , Earth's orbit may be crazy as well. It's VERY hard for a planet to stay in a perfectly stable orbit. Over time, small perturbations in the Earth's orbit might add up and throw us into a radically different apocalyptic orbit. Frankly, it's amazing that Earth has stayed in this relatively stable orbit THIS long.
As Sky said an orbit over time will stabilize. The only apocalyptic orbit would tend to happen as the planet's orbit decays and the orbiting object's altitude descends below its primaries Roche limit. For Earth it would have to degrade past the point of .5 AU. At present, the Earth is moving in towards the sun at about .00000005 AU per century. So in 10 billion years get ready for for planetary break up!

We have more pressing problems than Earth's degrading orbit:
http://img853.imageshack.us/img853/4425/073repentstephenhawking.jpg

Now it requires a massive force to knock a planet out of orbit. Neptune was struck by a object the size of Earth and all it did was knock it on its side, the eccentricity of Uranus's orbit is not that much higher than Earth's (for reference Mercury has the highest eccentricity of any planet), in fact Uranus's eccentricity is less than our moon's.

Most planetary systems end up with really eccentric orbiting planets.

Also considering that we have only accurately examined one star system (our own) stating that most planetary systems have eccentric orbits is premature. Once we have conducted long term study of the new systems recently discovered then we can start formulating such hypothesis.

BTW Planetary System = Earth and Moon or Jupiter and its moons. Star System = Sun and Planets.

[TLAM Strike]

There is a (true!) news story from India that would make a nice screenplay for a horror movie. A village there has been invaded by a claimed new species of spiders that are huge, unusually aggressive, and lethal. More than a dozen people got attacked and bitten, two died. The government has used chemicals in large quantities in and around the village. They have sent dead spiders to institutes around the world to have them helping in identification.

The spiders are half as big as a hand palm. And as said: very aggressive and obviously lethal.

It seems they have had a decently sized panic in that place.

Where is Hollywood when you really need it?

http://img641.imageshack.us/img641/8779/nukeorbit.jpg]

[Karle94]

We have more pressing problems than Earth's degrading orbit:
http://img853.imageshack.us/img853/4425/073repentstephenhawking.jpg


Doesn`t he know that the sun won`t explode. Its size will increase exponentially and then implode, creating a white dwarf. A sun that is 100-1000 times bigger than our sun expands and then explodes. The gravity collapses in on itself creating a black hole.

[TLAM Strike]

Doesn`t he know that the sun won`t explode. Its size will increase exponentially and then implode, creating a white dwarf. A sun that is 100-1000 times bigger than our sun expands and then explodes. The gravity collapses in on itself creating a black hole.

When our sun reaches the end of its Red Giant phase it will throw off the outer layers of matter in to a planetary nebula leaving behind a White Dwarf. To the layperson the sun will have "exploded".

[vienna]

This is going to happen in about 4 billion years? I don't know...let me check my day planner and I'll get back to you... :hmmm:

...

[Rockin Robbins]

In reality,neither the motion of our galaxy nor the motion of the M-31 system of galaxies has been observed long enough to form any valid conclusions about the shape of their paths through the universe.

Typically, these sensatioal press releases assume all kinds of ubsurd things including, but not limited to the supposition that these bodies are moving in a straight line.

There are many times when the instantaneous velocity of Earth points right at the planet Venus but I don't recall any sensational predictions of collision.

But we are all familiar with the planets' curved orbital paths, so we'd rightly laugh at such a perposterous claim. Only our ignorance prevents similar reaction to the above. We don't have enough evidence to say there a is a possibility, a likelyhood, or a certainty of a collision.

[Skybird]

In reality,neither the motion of our galaxy nor the motion of the M-31 system of galaxies has been observed long enough to form any valid conclusions about the shape of their paths through the universe.

Typically, these sensatioal press releases assume all kinds of ubsurd things including, but not limited to the supposition that these bodies are moving in a straight line.

There are many times when the instantaneous velocity of Earth points right at the planet Venus but I don't recall any sensational predictions of collision.

But we are all familiar with the planets' curved orbital paths, so we'd rightly laugh at such a perposterous claim. Only our ignorance prevents similar reaction to the above. We don't have enough evidence to say there a is a possibility, a likelyhood, or a certainty of a collision.
Mind to give your scientifically based assessement, or is this just a subjective rant based on belief? Because by scientific standards that we are capable of, we very well are capable to measure things like the parallax movement of distant stars in our galaxy. Or the velocity vectors of galaxies. Yes I agree it is remarkable what technology allows us to do, and the level of precision we can acchieve is truly stunning... We can also measure the red and blue shift, and by that say whether an iobject wins distance to us, or approaches us. We can even say at what speed the object revoles around its axis, and at what angle this axis is located.

So to add substance to your claims, you need to be able to prove that the measurements made, are erratic, or base on either erratic implementation of technological means, or base on implementing measurement technolgoy that is defective in itself.

BTW, this is not sensational publishing in some yellow press press. The public opress just says that these finding sget reproted it dedicated scientific publications/magazines.

[Rockin Robbins]

Thought experiment skybird: how long do you think it takes our Milky Way Galaxy to move one diameter of its disk? If it moved at the speed of light (relative to the averaged assumed rest velocity of that tiny part of the universe which is measurable its velocity is a small fraction of the speed of light) it would take over 100,000 years.

Let us use the analogy of an automobile. If it were to take 100,000 years to move one car length, could you tell me whether or not it was going to the 7-Eleven after keeping track of its position for 300 years?

I know that you may require some proof of concept, but I don't feel any need to further than that. Those above are easily verified. I have understated the size of the galaxy and overstated the velocity and it is still ridiculously obvious that no conclusions can be drawn.

M-31was only shown definitely to be a spiral galaxy outside our own in the 1910s by the 100" Hooker telescope at Mt Wilson, California. Any decently accurate positional data has only been known since the late 1700s. And this is not a three dimensional position database but only right ascension and declination over time.

It was only Edwin Hubble's discovery and study of Cepheid variable stars in M-31 during the 1930's that we began to get a vague idea (+- 50%) what the range to the galaxy is. Plus or minus 50% won't get you a torpedo hit and it can't establish a collision course either.

Consider that M-31 is a fuzzball of varying size and even shape, depending on observing conditions, that it exceeds the apparent size of the moon by two times in height and more than 8 times in width, exactly how does one plot its precise position from a ground based observatory anyway? You don't, that's how.

My facts are all easily proved and you will have to do that for yourself or you will have no reason to believe the unavoidable conclusion. Not only do we not know where the car is going but it will be a million years before it is out of its parking space.

Play the spooky music NOW!

Edit: can this be done using this Android tablet? To personally wrestle with the parameters for establishing reliable orbital elements see www.projectpluto.com/find_orb.htm. Sorry can't seem to paste a link.

[Skybird]

The maximum reasonable assumption on abberations in the Hubble constant that I find documented is not 50%, but around 20%. Which affects estimations on the distance. Honstely, if somebody tells me about an event starting in 4 billion years and takling place over 2 billion years, I do not torment my brain over ideas of whether it maybe is not 4 billion but 3.2 billion or 4.1 billion or 3.7 billion years.

Own-rotation would be calculated on basis of red-blue-shifts in the light coming from Andromeda. Since the object is so close and so big, we have a very solid calculation result on that, I would say.

Parallax shifts can be observed and recorded, and the greater the precision of the observation tools, the more precise the calculations we can run to get an idea on distances and relative positions of objects. Hubble now has allowed to measure sideby movement of M31 with that needed precision, they claim, and the results for the calculated vector are statistically consistent with the model scenario of a direct collision of both galaxies. Conclusion: both entities are on collision course.

As is scientific methodology, we measure, compare to models, and come to conclusions. We accept as a result or theory what is consistent with all informaiton that so far we have. If we get additional info, better ways of explanation, or get new measurement results due to increased precision of tools and these new results recommend adjustements of the former theory or conclusion, than theory/conclusion gets corrected and advanced accordingly.

That needs no tricking with thought experiments in this case. Keep the explanation of what we know as simple as possible. Don't add stuff that adds nothing to the explanatory value.

And regarding cosmology and astronomy and physics I have long since stopped to think that only what I can imagine can be reality. I recommend you do the same.

[STEED]

http://www.iphonewallpaperblog.com/wp-content/uploads/2011/01/bender%E2%80%91futurama-iphone-wallpaper.jpg
"Andromeda can bite my shiny metal ass".

[Rockin Robbins]

The maximum reasonable assumption on abberations in the Hubble constant that I find documented is not 50%, but around 20%. Which affects estimations on the distance. Honstely, if somebody tells me about an event starting in 4 billion years and takling place over 2 billion years, I do not torment my brain over ideas of whether it maybe is not 4 billion but 3.2 billion or 4.1 billion or 3.7 billion years.

Own-rotation would be calculated on basis of red-blue-shifts in the light coming from Andromeda. Since the object is so close and so big, we have a very solid calculation result on that, I would say.

Parallax shifts can be observed and recorded, and the greater the precision of the observation tools, the more precise the calculations we can run to get an idea on distances and relative positions of objects. Hubble now has allowed to measure sideby movement of M31 with that needed precision, they claim, and the results for the calculated vector are statistically consistent with the model scenario of a direct collision of both galaxies. Conclusion: both entities are on collision course.

As is scientific methodology, we measure, compare to models, and come to conclusions. We accept as a result or theory what is consistent with all informaiton that so far we have. If we get additional info, better ways of explanation, or get new measurement results due to increased precision of tools and these new results recommend adjustements of the former theory or conclusion, than theory/conclusion gets corrected and advanced accordingly.

That needs no tricking with thought experiments in this case. Keep the explanation of what we know as simple as possible. Don't add stuff that adds nothing to the explanatory value.

And regarding cosmology and astronomy and physics I have long since stopped to think that only what I can imagine can be reality. I recommend you do the same.

Amazing! You have completely ignored every point I've made. Is this how you discuss everything in your life? If you disagree, then make points, garner contraindicative facts. You've just changed the subject and claimed to be addressing the subject.

Ignored: what is the true velocity of the Milky Way? M-31? How long is our database of 3 dimensional positions and how accurate is it? You trot out Hubble constant mumbo-jumbo that you don't understand, for it has NO application to M-31 (too close, too large), you talk about parallax when that is a tool used only in intra-galactic star distances, and even that only within pretty close distances. It is as useful as a stadimeter for measuring the distance to M-31. Might as well use sonar.

How about an explanation of what parallax is and its application to the issue at hand? What kind of parallax are you referring to anyway? There are differing kinds of parallax you know. Within what distance parameters is parallax an appropriate tool? Parroting a technical term is not reasoning. You must demonstrate understand its meaning, application and limitations. That means numbers and references. I can do that. How about explaining why you ignore observations on the scale velocity of galaxies, that is, their velocities related to their size and hot long we have had to observe them? That is the purpose of my thought experiment, to cut through the jargon and mind boggling numbers to reduce this to something we can identify with: the motion of a car. The analogy illuminates concept that otherwise would completely escape our understanding. That is how I teach manual torpedo targeting, by the way, by reducing that which is difficult to understand to simple concepts that everyone can understand. Hundreds of people can attest that the method works and it works magnificently.

We think galaxies move incredibly fast. A scientist says that the Milky way is moving at 100 million miles per hour toward the Virgo Supercluster and we just saturate our brain cells, saying "Holy CRAP!!!". And we stop thinking. Well, your comment on imagination is exactly correct, although you refuse to apply it here, that is when we need to BEGIN thinking. We can so that by relating the motion of a body to its size. When we say a car is moving quickly we might be talking about typical freeway speeds, 70 mph, call it 110 kph. If a car is 6 meters long (big car) it moves at 30.5 m/s, or its own length in a fifth of a second. Based on its velocity and the maximum maneuverability, we can adequately predict where that car will be for several seconds after any given observation, regardless of what the driver does. After five seconds or so, the effects of any future maneuvering will rapidly make our predictions less and less reliable. Based on all that, we know the car is moving at 110 kps, its position can be reasonably predicted for five seconds no matter what the driver does and during that time it will move 30 times its length.

Reduce the galaxy to the size of a car. Assume it is moving at a speed hundreds of times faster than its actual motion through space, the speed of light. At that magnitudes too high velocity, this car will travel its own length in 100,000 years. I say that means that galaxies move incredibly slowly! Our numbers are just inadequate to achieving any understanding of their behavior at all. Looking at a car which would take 100,000 years to move 6 meters, you and I would immediately agree that it is parked. In fact there would be instrument on Earth that we could use to detect any movement! Don't be snowed by stupid high numbers. These eggheads do not want to communicate, except among themselves. The question here is how we determine any conclusions at all about the destination of a parked car! Answer: we cannot.

But that is not the question the scientists are asking. They are asking "How do we secure future funding." The answer, in part, is that learned article referred to by the original poster.

How about some explanation of how three dimensional orbital parameters are described, the six parameters which must be ascertained, the length of time necessary to establish them and the resulting accuracy.

Your task: establish that the thought experiment I proposed does not answer the question of "is it impossible that we know where either M-31 or our own galaxy is headed?" Establish the true spatial motion of the Milky Way! (Scientists have no idea). Establish the true space motion of M-31, projected for just the next million years. Are the galaxies of the local group in orbit around each other? How does that possibility influence future paths of the galaxies involved. How about a list of all galaxies in the local group? Scientists have no idea.

That is the gist of my reasoning here, based on thirty years of active interest in amateur astronomy and extensive conversations with professional astronomers who assure me that baseless speculation is often released as part of the popularization of astronomy.

Evidence is called for on that account. Several times upon discovery of a near Earth asteroid some testosterone inhibited astronomer wants to make a splash and makes the announcement, Asteroid xxxx is definitely on a collision course with Earth for the year 2014. It's newly discovered. Its orbital parameters have not been worked out to any acceptable degree of accuracy, nor CAN they be for at least several weeks, maybe several months. When that happens, invariably, so far, no collision is imminent.

Here you go (http://why.knovel.com/all-engineering-news/1303-scientists-say-more-observations-necessary-to-determine-whether-asteroid-is-on-a-collision-course-with-earth.html), a typically common chicken little story. Note that the scientists are not even going to BEGIN speculating about any possible collisions until they have continuous observations of that asteroid for two complete solar orbits. Only then will orbital parameters be worked out to a precision they can use.

Science is polluted by the political process, for that is where its money comes from. In order to attract money it is necessary to make spectacular and outlandish claims, the scarier the better. Medicine understands this. Astronomy understands this. NASA understands this. Why don't you?

You can't prevail in a discussion with vague insinuation and irrelevant hocus-pocus. I know you're the big cheese around here but in this case only, you really don't know what you are talking about. Your reasoning is logically fallacious appeal to authority and you do not understand the authority on even an elementary level. And imagination has no causal effect on reality. It can only help us discover what reality is. By not using imagination in this case, dismissing it as irrelevant "trickery" you are denying yourself knowledge.

During the entirety of human existence we have had the opportunity to watch M-31 move a tiny, unmeasurable fraction if its disk diameter through space. We have no idea what its true space motion is. We have one number: the component of its present velocity toward or away from Earth.

However we do not even know the distance from us to M-31. That number is subject to interpretation and contradiction, for there are three main methods used to study this.

Firstly, it was established by Hubble's study of Cepheid variables discovered there. I have held the photo in my hand where five or six variables are indicated by Edwin Hubble himself with the indication "var!" above each on the plate. A Cepheid variable is a giant star which is unstable and so it oscillates in diameter and magnitude. They exhibit a period/luminosity relationship. By measuring the period of variability, the time between brightest to brightest, you can derive the true luminosity of the star, within an error range, of course. Then by measuring the apparent brightness of the star and mathematically comparing it with the actual brightness, folding in some assumptions, like no light attenuating dust intervening, you can come up with a distance. Distances derived from Cepheid variable observations range from 1 million to 2 million light years distance for M-31. I have personally performed photometric analysis of those photographic plates and performed the calculations myself to derive the distance as Edwin Hubble did.

The second method also relies on assumptions. We assume that M-31 is roughly the size of our own galaxy, an assumption no longer believed. You realize that in order to subtend one degree in apparent size an object must be 57 times as far away as its size. We can assume that M-31 is approximately 100,000 light years across. The disk is about 4 to 5 degrees across, therefore it is 57 x 100,000 light years / 4 degrees away or 1,425,000 light years away. You can drop some digits. We really don't know to even three significant figures on that one. 1.4 x 10^6 light years would be a better expression of our understanding. Again, how do you even measure the diameter of the disk when it has no true edge?

The third method is the Hubble constant that you mentioned. Because the individual motions of the stars within M-31 are a large component in the small redshift we observe, and those motions are random to our viewpoint, the Hubble constant has been of little help there. Note that the value of the Hubble constant is being continually revised, argued and fought about, resulting in a wild expansion and contraction of the universe. The universe doesn't care too much about our Hubble constant. It is whatever it is and the size of our ignorance is astounding, while we claim knowledge that we are nowhere near. And if the Hubble constant were as accurate as the speedometer of your car, all it does is measure the radial component of the object's motion. There are many other unmeasured components. Are you merely going to assume what they are? Do you know what radial motion is, and understand the application of the Hubble constant here? I do. Suffice it to say that what it tells is dwarfed by the magnitude of what it does not tell.

Distance to M-31: between 1 and 2 million light years. That's a really nice range there. Now: is it going to the 7-Eleven?

[Skybird]

What I am saying is that as long as we have no better ideas and approaches and data, we are best advised to stay with the best way to put the pieces together that we currently can come up with. And in a basic understanding that is what science is about. Nowhere I have claimed absolute certainty.

What I pointed at is that your initial claim (that you cannot imagine things were like is being said here) is not enough to beat the method of how the theory so far has been put together.

If it was a flawed job they did on the collision claim now, it will sooner or later get corrected or proven wrong. Until then it is the best explanation and prediction we have. And certainly better than just saying that one cannot image things to be like that.

Yes, many questions remain, and with each answer, new questions form up. I already have realised that myself, thank you. But last time I read about Andromeda (no, not systematically, it still is hobby, not profession), it seemed to me that we seem to have a little bit more to say about it's dimensioning than you want to accept here.

I recommend to get the published original article of the NASA team that ran the measurement of the sideby movement and did the math, and check their explanation of their methods for methodologic inaccuracies. That's the right way to proceed, as I understand science's ways:

The Hubble observations and the consequences of the merger are reported in three papers that will appear in an upcoming issue of the Astrophysical Journal.

Again, all I appeal for is that we simply go with the so far best model we can come up with. That has, imo, a better chance for turning out true, than just any wild speculation. And it seems that the best way to bring together the observations we have in one consistent model, is that Andromeda and Milkyway are on an apporoach course that will make them merge in around 4 billion years.

If we get better data and observations at some later point, or learn that our past method was flawed and produced corrupted data or misled conclusions, we will refine our model.

P.S. http://www.nature.com/news/andromeda-on-collision-course-with-the-milky-way-1.10765
Darling and his colleagues are now measuring Andromeda***8217;s sideways motion in another way, tracking the position of a collection of water masers that he discovered in the galaxy. These objects are regions of radio-bright emission associated with star formation. In about two years, he says, he and his team expect to obtain an even more precise value than Hubble's for the sideways motion.

Sideway motion, not sideby motion. I need to finally burn that into my mind...

P.P.S. And where do you get that range estimation of 1-2 million lighyears from? I recall that they usually point out four or five different estimations, all of them based on different methods, and I recall that they all have been in the 2.5 million range.

P.P.S. 2.0

Wikipedia has it, too (http://en.wikipedia.org/wiki/Andromeda_Galaxy#Recent_distance_estimate). Under "recent distance estimate". Four methods, all delivering mutually supporting data. And note that the cepheid variable method is there again, with results not from 80 years ago, but 8 years ago.

[Rockin Robbins]

What I am saying is that as long as we have no better ideas and approaches and data, we are best advised to stay with the best way to put the pieces together that we currently can come up with. And in a basic understanding that is what science is about. Nowhere I have claimed absolute certainty.

What I pointed at is that your initial claim (that you cannot imagine things were like is being said here) is not enough to beat the method of how the theory so far has been put together.

If it was a flawed job they did on the collision claim now, it will sooner or later get corrected or proven wrong. Until then it is the best explanation and prediction we have. And certainly better than just saying that one cannot image things to be like that.

Yes, many questions remain, and with each answer, new questions form up. I already have realised that myself, thank you. But last time I read about Andromeda (no, not systematically, it still is hobby, not profession), it seemed to me that we seem to have a little bit more to say about it's dimensioning than you want to accept here.

I recommend to get the published original article of the NASA team that ran the measurement of the sideby movement and did the math, and check their explanation of their methods for methodologic inaccuracies. That's the right way to proceed, as I understand science's ways:



Again, all I appeal for is that we simply go with the so far best model we can come up with. That has, imo, a better chance for turning out true, than just any wild speculation. And it seems that the best way to bring together the observations we have in one consistent model, is that Andromeda and Milkyway are on an apporoach course that will make them merge in around 4 billion years.

If we get better data and observations at some later point, or learn that our past method was flawed and produced corrupted data or misled conclusions, we will refine our model.

P.S. http://www.nature.com/news/andromeda-on-collision-course-with-the-milky-way-1.10765


Sideway motion, not sideby motion. I need to finally burn that into my mind...

P.P.S. And where do you get that range estimation of 1-2 million lighyears from? I recall that they usually point out four or five different estimations, all of them based on different methods, and I recall that they all have been in the 2.5 million range.

P.P.S. 2.0

Wikipedia has it, too (http://en.wikipedia.org/wiki/Andromeda_Galaxy#Recent_distance_estimate). Under "recent distance estimate". Four methods, all delivering mutually supporting data. And note that the cepheid variable method is there again, with results not from 80 years ago, but 8 years ago.
Again, that is a popular article, not a scientific article. The question it is meant to answer is "How do we obtain future funding?" The answer is by snowing unquestioning people who will accept whatever "wild speculation" and that is the best description of what they say, that they decide to claim.

In astronomy there is no "sideways motion." There is radial motion and proper motion. Combining radial and proper motion vectors can give a solution to the spatial movement of an object, subject to the error ranges of the two numbers.

However the result is instantaneous velocity. It takes into effect no future perturbations in the path and assumes that there are none. That is an invalid assumption for any astronomical body known. We have never detected any astronomical body whose motion is in a straight line. All of them are moving in curved paths, usually elliptical. Therefore the conclusions are invalid if they are evaluated for truth based on their conformance with scientifically supportable prediction. The probability that the galaxies will continue in a perfect straight line corresponding to their present instantaneous velocities is zero. The nature of those future paths and their relationships to each other are entirely unknown. Therefore a prediction of future collision, even if it were to turn out later to be true (how will we ever know?) is poppycock and flim-flammery of the first degree.

However, based on an evaluation of "Does this claim qualify us for future funding?" the evaluation is that the statement is true.
You still ignore all contentions I have made and have made no progress invalidating the reasons that prediction of a definite or likely collision of M-31 and the Milky Way is entirely speculative and without scientific validity.

By the way, the Wikipedia article you referenced contains a partial statement of my reasoning, saying, "The Andromeda Galaxy and the Milky Way are thus expected to collide in about 4.5 billion years, although the details are uncertain since Andromeda's tangential velocity with respect to the Milky Way is only known to within about a factor of two.[67] (http://en.wikipedia.org/wiki/Andromeda_Galaxy#cite_note-66)" I appear to be vindicated by a careful writer there. Congrats to him. However, I assure you my opinions are not maverick opinions and meet with the approval of astronomers, both professional and amateur.

By way way, I never said that it was impossible to imagine anything like that happening. As a matter of fact, Harlton Arp, a friend of a retired astronomer I've spent a good time with, has an entire compendium in his Atlas of Peculiar Galaxies, many of which are interacting pairs or groups of galaxies, showing collisions, near collisions, cannibalism by huge galaxies of nearby lighter weight 90 pound weaklings, hundreds of photos of what you claim I said was unimaginable. We don't have to imagine it, we're watching it happen! You can too, without photos and without excessively expensive equipment.

One of my favorite galaxies, partly because it is so little observed in spite of being BIG, bright and in an easy to find place, is NGC 4338, the Beached Whale Galaxy. It is eating a nearby neighbor for lunch, casually dismembering it in clear view of anybody with a 13" telescope or larger. When showing this one off to the curious I always refer to the pair as the Beached Whale and the Hapless Guppy. The Hapless Guppy is all twisted into an almost fish hook shape and there are very faint tendrils of material being devoured by the hungry giant. You can't see the tendrils in anything smaller than about a 30" scope. It's a sight you won't soon forget and you can see it with your own eyes, actual photons which were part of the actual objects impacting on your retina, telling a story more amazing than any unassisted imagine would dare to venture. You don't need photography. You don't need a multi-million dollar instrument. And you can literally touch the stars and interact with their photons. Find an amateur astronomy club near you and find how small is our imagination compared to verifiable reality. It is properly humbling.

Every collision between imagination and reality shows that the universe is not only stranger than we imagine, it is stranger than we CAN imagine. Stolen from Isaac Assimov, who was right.:D

[Skybird]

Let'S wait for the publication of their three articles. I realise that you seem to know some stuff of this all, and probably more than I do. But I also realise that some of your claims are exotic, to put it this way, seem to reflect a status of knowledge that is a little old, and violate everything I know from the occasional read in a mag here and there, or a specialised astronomy book, or a documentary. That's why I do not just beleive your claims blindly. Until then, I stay with the established model of that we have a fairly reaosnable idera of how big Andromeda is, how far away it is, and that both galaxies seem to apprpoach each other and seem to collide with each other one day. The news odf the day is not that they will collide - this is known since long - I already larned that in astronoym course in school - in the early 80s. The news today is that they have given a time estimation based on 8 years of continuous observation. And it seems they hope to boost or even precise that estimation even more when in two years their current monitoring project has ended.

Your claim that they just published sensational bollocks to raise fundings, needs evidence. Could absolutely be like you say - I know that that stuff happens, and that academical business is heavily corrupted. Still, one needs to check every single case to differ between serious work, and the bollocks-talkers. Just assuming them guilty on basis of generalisation from former bad examples in the business, is not good enough.

P.S. Please note that here, likle in opther debates, I do not state absolute certainties. Scientific theories are temporary, I fully understand that, and as I said in an earlie posat, I just stick withg what by the present status introduces itself as the most simple model to bring our observations results together with the smallest contradiction possible. the findings they came up with now they described as "to be consistent with what you would expect in case of a collision scenario of both galaxies." Well, thus the - preliminary, if you want - conclusion. But again, the real news is the time estimation, not the predicted event itself.

I think it is possible that in principle we are not as far apart as it may appear.

Every collision between imagination and reality shows that the universe is not only stranger than we imagine, it is stranger than we CAN imagine. Stolen from Isaac Assimov, who was right.:D
"The truth, as always, will be far stranger." Arthur C. Clarke, foreword to "2001". Who stole from whom? :)

[Rockin Robbins]

But is it corruption if that is the only way to secure funding for research, especially research in cosmology which will not put dollars or Euros into any of the politicians' constituents' pockets?

I say good on 'em! If these claims make more people curious or encourage one school age math wizard to abandon an accounting major and take up astronomical physics I say the claim was not wasted! Even if they are preposterous, we can't be afraid to ask the big questions. And we can't insist on immediate economic payout from basic research.

Arthur C Clarke and Issac Asimov were kindred spirits. I'll bet they shared a lot of similar sentiments and ideas. Where are the Asimovs, Clarkes, Heinleins or Simaks of today? All we have is post-apocalyptic cookie cutter horror stories, parading as science fiction. Those guys dared to hope! And hope is the legitimate subject matter of science fiction!

Hey, here's why we don't need imagination in this case. This is a photo of Stephan's Quintet, an interacting galaxy group of faint galaxies you'd have trouble seeing through a 10" telescope, would have a decent chance with a 13" (my scope is 13") and would have a great time seeing with anything larger than a 16". You can see much of the detail in the photo through a larger sized amateur scope.
http://upload.wikimedia.org/wikipedia/commons/thumb/3/31/StephansQuintettIlustrated2.gif/500px-StephansQuintettIlustrated2.gif

Yes, I'll bet the realization of how stationary the galaxies are was a bit novel. It sure was to me until I translated the math into English and dared say it.

By the way, I can now extend my car analogy just a bit by substituting our best information of the spatial velocity of the Milky Way galaxy for the speed of light. Now the speed of light is 300,000 km/s of course, but expressed in km/hr it's 1.09 billion km/hr. Our best estimate of our galaxy's speed through the local medium (we're not even taking a stab at a figure for absolute velocity. What is that anyway?) is 2.1 million k/hr. now expressed in millions of km/hr the speed of light is 1,090 million km/hr, so it moves 519 times slower than the speed of light. That means instead of 100,000 years to move its own diameter, the Milky Way takes 51,900,000 years to move its own diameter through space.

Let's make a bad assumption and posit that speed has not changed through time. Let's round off that time to 50 million years to move one diameter of the galaxy. Heck, what are a couple of digits among friends? That means the galaxy is moving about 20 times its diameter every billion years. I know they have a high falutin' number but we know it's garbage (error .11 billion years, don't make me laugh....) let's say the universe is 13 billion years old. According to present thought it's fractionally older than that.

That would imply that our galaxy has only moved 13 x 20 times it's own diameter, a whopping 260 diameters. If it were that 6 meter long car it would have moved 1.56 kilometers since the beginning of time. We really need to buy a faster car!:har:

Oh, the 7-Eleven is 4 km away..... We're not there yet.

[Skybird]

I read again your posts and maybe identified one of the things that irritated me and maybe led you to your way-off estimation on the distance between both galaxies. You did not mention that there are two classes of cepheides, type-I and type-II. Leavitt'S formulation of how brightness and a cepheide'S cycle are related, is valid only for one of the classes, and when Hubble used Leavitt'S relation on the cepheides he observed in Andromeda, he could not know that these cepheides where of the "wrong" type". Thus Hubble underestimated the range by a factor of 2 because he underestimated the real brightness of those cepheides he was observing.

It was an implementation of the right method, but in a wrong way. The method itself is valid until today. That is why the cepheide-observation from 2004 as quoted in Wikipedia today delivers correct data that are consistent with the range estimations won by other methods as mentioned.

Sorry if I confuse you by choosing wrong terms maybe. Of course I read these things in German, and sometimes the labels are very different (for example we call Cepheides not type-I and Type-II, but "klassische Cepheiden " and "W-Virginis-Sterne"), or I simply do not know the English equivalents. For example "Perioden-Leuchtkraft-Beziehung" - no idea what that is in English.

[Rockin Robbins]

You do very well in English, as you know. Yes, Henrietta Leavitt--a forgotten woman who did the lion's share of the astronomical heavy lifting during the Hubble era. She's a true hero of mankind.

Isn't it interesting that the geometric analysis of angle subtended projected from the 100,000 light year size of our galaxy also comes out somewhere close to 1.5 million light years away? Of course the geometric analysis is a correct calculation so that means some of our parameters are wrong there too.

It's a case of two flawed reasonings "confirming" each other. It is difficult to detect errors like that. Even now, further findings of basic "constants" grow and shrink the universe to an alarming degree. The universe doesn't seem to mind though.

And all this is based on assumptions. We assume that the period/luminosity relationships of the Cepheid variables is correct. We know it will be further refined. They have other families of variables they use now also the cross-check.

It's fun to speculate how much we "know" will be modified beyond recognition. When I was in high school, I memorized Avagadro's number, 6.023 x 10^23. That is the number of molecules of a substance that constitutes a gram-molecular weight of that substance. Let's take Oxygen. its atomic weight is 15.9994 (it's less than 16 because of the mixture of different isotopes of oxygen floating around. This is an average weight based on the distribution of isotopes found here and now). The molecular weight is double that because oxygen runs around in pairs as a stable molecule. So its molecular weight is 31.9988. So Avagadro's number of molecules, 6.023 x 10^23 molecules would weigh 31.9988 grams.

Except I found the other day that they've changed Avagadro's number! It's now 6.0221415 × 10^23

The end is near! http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/95fad14e.gif

[Skybird]

I started to love atsronomy and cosmology in school already. That was in the 80s. But staring through any of the telescopes the private household can buy for affordable money was always boring to me. Once you have seen the moon at close detail, maybe projected the sun onto a screen and spotted the occasional dark spot, and have identified the six biggest moons around Jupiter or Saturn, it becomes kind of uninteresting, at least for me. And stellar objects, double stars and such things always just seem to be white tiny spots against dark background. You cannot hope to get images from these like you see in books or on TV. For this, the internet is a blessing since it allows you access to a much more potent "telescope", the virtual telescope by Microsoft and the huge photography database behind that interface. Now there we talk astronomy! That thing is wonderful. The internet was meant for stuff like this, like Google Earth.

My interest always was more on understanding the how and why, and I read about that. I then had a long pause from astronomy and physics, and then started a refresher with the phantastic book and web-course by Bennett, Donahue, Schneider and Voit, 5th edition, German. Maybe you know it. That is a truly fantastic book, and it defines pretty much both the basis and the limits of what I ever learned about this matter. Although I admit, that due to lacking practice I forgot much of it again, and for the most kept an oversight in memory only. The issue about the cepheides for example I only vaguely remembered, I knew there was something, and I knew where to sort it and what it means for measuring distances, but the details about the controversy back at Hubble's time and why he underestimated the range I needed to refresh and look up again. But that is okay, I know that it is there and where to find stuff, and since I am no pro depending on always knowing the details out of the blue, it is okay as long as I keep that overview and the basics - I must not know every specific detail, I can look it up if needed.

Just to give you an idea of what you can expect from me about my intellectual horizon regarding astronomy - and what would be beyond my understanding and knowledge. That book pretty much describes my basis and limitations. In principal I hold a simliar level of information about physics, subnuclear physics I mean. No specialist I am, but a generally interested, fascinated layman who read a bit beyond the newspaper education. It's very exciting and fascinating.

In Germany you cannot study astronomy as a separate branch (it is only a minor single course in physics studies here), else I maybe would have ended up in that branch - the interest was there, especially on cosmology. Which probably would have been a bad idea. There are not many jobs to secure for astronomers. Maybe some more in America, I am not sure, but in Europe they are rare.

P.S. So Leavitt was a she, not a he. Hear-hear! :) See, that I did not know.

[Takeda Shingen]

In before TLAM Star Trek macro.

Oh....wait.

[Rockin Robbins]

I agree with you on the stellar and lunar astronomy. Very little of note to look at white dots. I do love globular and open clusters though. They have personality.

One memorable occasion a friend and I were at the Winter Star Party in the Florida keys pulling an all-nighter on a spectacular night with his 20", that's a 508mm telescope. It's no toy. And we were demonstrating that you don't see with your eyes, you see with your brain. The brightest globular cluster is Omega Centauri, a dense collection of a million stars arrayed in a perfectly round snowball shape with the stars the tiniest imaginable pinpoints. It will take your breath away to see a million stars packed into an area just a fraction larger than the full moon.

Well we were demonstrating Omega Centauri Psychosis, I called it. We selected a magnification that contained the entire cluster with a donut of black around the edge and began announcing to neighbors that we would show them something amazing. We started by explaining what was about to happen. First you will look through the eyepiece and see a million stars, just as you expect. But 30 seconds in or so your primitive brain will begin constructing patterns: a triangle here, a parallelogram there, a square there, one after the other and then in a single second the entire cluster will crystalize into a three dimensional crystalline shape. You will not be able to see a single star until you step away from the eyepiece.

They knew we were crazy. They've looked at this cluster a hundred times before. They know what it looks like. So they called us some not so nice names and sidled up to the eyepiece. "What do you see?"

"You know what I see, I've seen it a hundred times before, a million stars..."

"Keep looking. Be patient."

"AAAAAAAARRRRRRRRRGGGGGGGGHHHHHHHHHHHH!" They'd scream out in amazement. Which brought more victims. Between 4 am and sunrise we had shown over 100 people and they all saw the phenomenon. There were plenty of similar screams. It was the most fun I've had with a telescope and a learned crowd of America's top amateur astronomers.

[Skybird]

Hehe, I were a psychologist, longer time ago, not anymore. Human brains forms patterns. human brain thinks in patterns, human brain cionstructs patterns. Even a symmetric grid of dots gets interporeted not as a grid of dots, but either as lines of dots, or columns of dots, depending on the spacing. Now add to this phenomenon that more imminent needs, even interests, push into the foreground of awareness, with less urgent ones disappearing in the background, add the occasional dose of genetically programmed schemes and instincts, and you get an idea of how predetermined our behaviour and decision-making is and how constructive our perception is. I know that there are neurologists and psychologists that simply doubt that there is something like a "free will".

And then move into the realm of love, sexual drives, and have a got laugh at this naked ape and how he tries to tell himself that he chooses on decisions! Good excercise in laughing out loud. :D

[Rockstar]

:D
http://www.geekologie.com/2012/01/04/nerds-vs-geeks-cut.jpg

[Skybird]

Wowh - it seems I'm two in one then! That would also explain the other voice in my head!