NASA can now predict Andromeda collision with certainty | Hacker News Reader

NASA can now predict Andromeda collision with certainty

science.nasa.gov

69 pointssytelus20 comments

Fascinating.

"It is likely the sun will be flung into a new region of our galaxy, but our Earth and solar system are in no danger of being destroyed."

Pretty close, but not precisely zero danger -- and from a broader perspective, this is a curious statement when by this point in time, four billion years from now, the Sun will be nearing the end of its life and will already have roasted the Earth into sterility (barring intelligent intervention).

"Simulations show that our solar system will probably be tossed much farther from the galactic core than it is today."

This bodes well for the long-term safety of the Solar System; it should be less likely to be broiled by supernovas or black hole accretion disk x-ray emissions further out from the merged core.

"Previously, it was unknown whether the far-future encounter will be a miss, glancing blow, or head-on smashup. This depends on M31’s tangential motion. Until now, astronomers had not been able to measure M31's sideways motion in the sky... The Hubble Space Telescope team, led by van der Marel, conducted extraordinarily precise observations of the sideways motion of M31 that remove any doubt that it is destined to collide and merge with the Milky Way. 'This was accomplished by repeatedly observing select regions of the galaxy over a five- to seven-year period,' says Jay Anderson of STScI. ... The space shuttle servicing missions to Hubble upgraded it with ever more-powerful cameras, which have given astronomers a long-enough time baseline to make the critical measurements needed to nail down M31's motion."

The Space Shuttle really made major contributions to science by allowing regular maintenance and upgrades to the Hubble Space Telescope.

"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."

The articles don't appear to be listed yet in the Table of Contents for an upcoming issue of ApJ. Stay tuned...

Edit to add:

http://hubblesite.org/newscenter/archive/releases/2012/20/vi...

This computer model video of the next eight billion years in a minute and 16 seconds is mind-blowing.

I highly reccommend watching the video simulation of the collision: http://hubblesite.org/newscenter/archive/releases/2012/20/vi...

Phil Plait also has some good commentary over at Bad Astronomy: http://blogs.discovermagazine.com/badastronomy/2012/05/31/ho...

Reminds me of the the galaxy xscreensaver hack.

Note that already after 0.8 billion years, on Earth, "Carbon dioxide levels fall to the point at which C4 photosynthesis is no longer possible. All plant species die. Free oxygen eventually disappears from the atmosphere.[23] Multicellular life dies out.[25]".

And after 3.5 billion years, "Surface conditions on Earth are comparable to those on Venus today".

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

So I guess it doesn't matter that much for humans what happens with the Earth on the collision. Either we managed already to colonize other planets and then the human race will like survive somewhere. Otherwise, we were probably doomed earlier anyway already.

Even if we settle on a bunch of other planets, I imagine we will always remain interested in preserving Earth as well. It will always be our original home. And astrophysical engineering of the solar system should enable us to keep the Earth in good shape well beyond the solar system's lifespan if left to its own devices.

More thoughts on the far future prompted by this thread here: http://bfe242.com/the-stars-like-sea-froth

"I imagine we will always remain interested in preserving Earth as well."

Interesting thought, but after a few generations (or maybe 10+) of being born on some other planet, or some combination of other planets, people will have almost no relation to, or particular interest in earth. Let alone a million years after the fact. Heck, I have no idea where my ancestors are even from if I go back more than 5 generations. Does the entire human race currently have some interest in preserving some place in Africa or Mesopotamia? Doubtful. I'm not arguing here, I just think it's an interesting thought, about how quickly (relatively) we lose track of where "we" are really from.

About 100,000 years ago, the entire subspecies of Homo sapiens sapiens -- all of our ancestors -- consisted of about 2,000 to 5,000 individuals living around the Rift Valley in Kenya. What if they had built museums of their art, culture, and science, parks, gardens, temples, and libraries that had been preserved ever since? What if all of life had also originated there and spread out since then, and the ecosystem there was by far the oldest in existence?

I don't doubt there might be many of our descendants who think or know little of the Earth, but I think there would also be various causes for enduring interest among many.

If the process happens slow enough we could always borrow into the earth and live off underground farms, use heat exchangers between the core and surface (or reactors) for power. Maybe someday we'd even forget there was a universe beyond the surface/atmosphere.

I'll admit it. I'm as skeptical of this as I am of religious claims.

'"Our findings are statistically consistent with a head-on collision between the Andromeda galaxy and our Milky Way galaxy," adds Roeland van der Marel of the STScI.'

How the hell does one establish statistical consistency when predicting an event four billion years in the future across 2.5 million light years? The sample size which has been analyzed is zero.

"The Hubble Space Telescope team, led by van der Marel, conducted extraordinarily precise observations of the sideways motion of M31 that remove any doubt that it is destined to collide and merge with the Milky Way."

Here is the fundamental fallacy at heart of the matter - the very one which makes this certainty bad science: the degree of precision with which one makes their measurements has absolutely no bearing on the accuracy of those measurements. Instead it indicates that all the errors were repeatable.

Science does some wonderful things...when it uses its own original methods rather than relying on faith that its high purpose makes its conclusions true.

You're right to be skeptical, but this isn't a religious claim. It's the best prediction these scientists came up with based on current theories of relativity/cosmology and measurements from Hubble.

This is the best science can do when experimentation is impossible: apply theories to measurements.

The hypothesis is no more verifiable than a claim that our actions in this life determine our circumstances in the next one. Indeed, I have better evidence for an hypothesis regarding karma right here on HN.

Do you rely on faith when you expect the next full moon according to your calendar? What about your belief that the sun will come up tomorrow?

Most of our science is done without the benefit of a laboratory at all. Historical sciences (paleontology, geology, etc) and cosmology have to rely on other methods. It doesn't make them based on faith.

The number of observed full moons is significantly greater than zero. In addition any prediction of the next full moon is verifiable within a few days. Finally, observations of the full moon do not depend on access to equipment not accessible to the general public.

In other words, in regards to the full moon I am not required to place my trust in others based upon their ritualistic training or privileged access to an unseen world.

At its heart, this is straightforward mechanics using precision measurements of the tangential motion of a statistically large sample of bright stars in Andromeda, as opposed to trying to track every single star in Andromeda (impossible of course), combined with radial motion easily measured by the Doppler shift on spectral lines. We know how to do this.

There are three separate papers that have been accepted for publication in The Astrophysical Journal but haven't appeared yet. Let's see what they say.

>"There are three separate papers that have been accepted for publication in The Astrophysical Journal but haven't appeared yet. Let's see what they say."

The metaphysical equivalent of an Encyclical. Swapping one group of experts for a group of experts with different training doesn't get one anything without the premise that the new experts espouse the one true view.

> Although the galaxies will plow into each other, stars inside each galaxy are so far apart that they will not collide with other stars during the encounter.

Wow, that is just impossible to fathom.

Not impossible.

It just takes a lot of fathoms.

The nearest star is 2.3796167e+16 fathoms from Earth.

The Andromeda Galaxy is presently about 1.3e+22 fathoms away.

It's approaching the Milky Way at roughly 5.8e+8 furlongs per fortnight.

Fabulous and fascinating. Question is whether earth can survice the onslaught of existing human activity in next billion years rather than collision from next 4 billion years.

Earth will easily survive humanity, even if we carpet bomb the surface with nuclear weapons. Even life is very likely to survive in its own niches as it has done during past global catastrophes. So worrying about earth is unwarranted in my opinion. Humans should be mostly concerned about their own species surviving in the foreseeable future. And so far I do not see any imminent danger of that happening, especially with our masterfully understanding to adapt our environments to suit our needs. But developments like global warming could lead to some drastic population swings in the future (e.g. via wars, famine, etc.).

Oh, and live will be gone on earth anyway, AFAIK in about 1 billion years when the sun has become so luminous that the oceans on earth will vaporize and ultimately escape into space. And the collision between the galaxies will very likely have no immediate effect on our solar system due to the vast space between stars (and therefore planets).

Good bases for next years Deep Impact/Armageddon movie head-to-head.

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