Talk:Timeline of the far future/Archive 2

Archive 1

Archive 2

Archive 3

Archive 4

Archive 5

Stellar collision

About 3 × 10¹³ years - an estimated mean time for the Sun to collide with another star in the current solar neighborhood. See:

Tayler, Roger John (1993), Galaxies, structure and evolution (2nd ed.), Cambridge University Press, p. 92, ISBN 0521367107

Regards, RJH (talk) 15:58, 30 September 2011 (UTC)

Thanks! Added. Though, I'm assuming that by "collide" the article actually means, "pass by close enough to gravitationally affect the planets", right? :)Serendi^podous 16:27, 30 September 2011 (UTC)

The article has a collision cross-section criteria based on mass and velocity, so I assume the author means it has some sort of close tidal interaction that would radically alter the momentum of both stars. It is unclear on the specifics, but I suspect that would significantly disrupt the Solar System. I'm just speculating, of course. Regards, RJH (talk) 21:23, 7 October 2011 (UTC)

Julian and Gregorian one year apart

I always thought the answer to this question was 48900, but this article says 48699. Please do calculation to find what year is right:

• 1900 = 13 days
• 2100 = 14 days
• 2200 = 15 days
• 2300 = 16 days
• 2500 = 17 days

Notice that 3 days are added every 400 years. Therefore, we must know when they are 14 days apart (14 and 365 are both numbers of the form 3n-1) and this is 2100. Then, we know 365 - 14 = 351, and 351 / 3 * 400 = 117 * 400 = 46800. Then we add 46800 to 2100 and get 48900. Is this right?? Georgia guy (talk) 17:32, 6 October 2011 (UTC)

Well I'm not sure. The citation says how the calculation was arrived at: 365.2425/(365.25-365.2425). or 365.2425 (a Gregorian year)/0.0075 (the difference between a Gregorian and a Julian year).Serendi^podous 19:22, 6 October 2011 (UTC)

Please check the above info I wrote to see what error there is in it. I have in my memory very well that the calendars were 13 days apart in 1900. Georgia guy (talk) 20:19, 6 October 2011 (UTC)

According to the Fourmilab calendar converter, the first day that a nominal date in the two calendars is one year apart is Gregorian 48901 March 1 which is Julian 48900 March 1. This marks the first day of a four year period during which all nominal dates remain one year apart. For the next century the nominal dates remain one year apart except for the year between the Gregorian and Julian leap years which then occur one year apart (e. g., Gregorian 48904 is Julian 48903). Subsequent periods within that century during which nominal dates are one year apart are only three years long. — Joe Kress (talk) 20:31, 6 October 2011 (UTC)

Joe Kress says that I must be right. But how are they only three years long?? What interval comes between these periods and how long is it?? Georgia guy (talk) 20:41, 6 October 2011 (UTC)

I'm kinda wary of using that guy as a source. If you read some of the other stuff on that site, you realise he's a bit crazy, so even if he's right, that would still violate WP:RS. I think the best thing to do for now is just just remove the fact until it can be properly verified. Serendi^podous 20:42, 6 October 2011 (UTC)

How does it violate WP:RS?? Georgia guy (talk) 20:44, 6 October 2011 (UTC)

Because it's a personal hobby site by someone without a recognised credit in an appropriate field, who, it appears, is also a bit bonkers. Serendi^podous 20:45, 6 October 2011 (UTC)

Can you see if my calculation is right yourself?? Use the fact that the Julian and Gregorian calendars were 10 days apart when the Gregorian calendar was introduced in 1582 and the difference goes up by one day every time a year divisible by 100 but not by 400 is reached. Then find when the difference reaches 365 days. Georgia guy (talk) 20:49, 6 October 2011 (UTC)

365 days? Or 365.25 days? Or 365.2425 days? Serendi^podous 20:53, 6 October 2011 (UTC)

It has to be 365; the number of days the calendars are apart goes directly from n to n+1 when a year divisible by 100 but not by 400 is reached (without going through decimals.) Georgia guy (talk) 20:56, 6 October 2011 (UTC)

[outdent] Are we sure that the two calendars were 10 days apart in 1582? Serendi^podous 21:11, 6 October 2011 (UTC)

Yes, that is definitely a true fact. Georgia guy (talk) 21:28, 6 October 2011 (UTC)

The papal bull Inter gravissimas which established the Gregorian calendar stated that ten days were dropped so that the day after 1582 October 4 was October 15 instead of October 5. The primary error in 48699 is that the original calculation ignored the offset. The Julian and Gregorian calendars (both with proleptic years) had the same nominal dates between 200 March 1 and 300 February 28, a 200 year offset from year zero for the first year of that period. Thus 48699 + 200 ~= 48901. More detail is needed to explain the remaining two year difference.

The first period of exactly a one year difference (365 days) between the same nominal dates in the two calendars was only three years (48904−48901), so all such periods during the century following 48900 were three-year periods. During that century, the Gregorian leap day is one year before the corresponding Julian leap day. For example, Gregorian 48904 February 29 is one year before Julian 48904 February 29, so the Gregorian leap day creates a one day difference which is not corrected until one year later by the corresponding Julian leap day. This removes one year from every four-year period during the century.

I would have liked to cite Calendrica, which was created by the authors of Calendrical calculations, a book acknowleged by many writers for its authoritative algorithms. Unfortunately, its latest allowable Gregorian date is 46499 March 2, a bit too early for this problem. — Joe Kress (talk) 05:08, 7 October 2011 (UTC)

I've added a ref from the link you provided. It's good enough for me; whether it will be good enough when I finally take this to FL, I can't say. Serendi^podous 08:24, 7 October 2011 (UTC)

uncited facts

Anyone know where to find these?

75,000: Time until the last manmade infrastructures completely deteriorate if humanity should go extinct. I'm assuming this is from The World Without Us, by Alan Weisman. Page number would be nice. Although, it isn't strictly speaking a future time, as humanity's extinction could happen at any time. Perhaps it would be better placed in Terasecond and longer.

500 million: Temperatures on Earth rise to the point where ice ages are now impossible. Earth's continents will become unrecognizable by then.. Interesting. Can't think where the source came from though.

950 million: The last animal life die out. I find this iffy. The oceans will have boiled to almost nothing by this point, so animal life would have had little to work with for some time. Still, it's probable that animal life will survive the demise of photosynthesis for some time, though I doubt it would be for very long, geologically speaking, unless some way of replenishing the oxygen in the ocean could be found. Serendi^podous 14:27, 25 October 2011 (UTC)

Please remove doomsday argument

Its an absolutely fallacious argument, as explained in the article's discussion. We can be in any part of human timeline with the same probability, we have to be somewhere even though the probability is tiny, is like the antropic principle.. — Preceding unsigned comment added by Jbbinder (talk • contribs) 22:10, 13 November 2011 (UTC)

It has been cited in many sources and is therefore notable. Someone's personal opinion as to its validity is not a valid reason for removal. Serendi^podous 09:12, 14 November 2011 (UTC)

Global catastrophic risks

This looks like it may be a useful reference for this article:

• Adams, Fred C. (2008), "Long term astrophysical processes", in Bostrom, Nick; Ćirković, Milan M. (eds.), Global catastrophic risks, Oxford University Press, pp. 33–44, ISBN 0198570503

Regards, RJH (talk) 16:43, 19 November 2011 (UTC)

Not really in a position to read books at the moment (essay deadlines) but thanks, that does look like it might be useful. Serendi^podous 13:14, 20 November 2011 (UTC)

Cool article

interesting seeing all these different timescales compared to each other.--Hermajesty21 (talk) 15:31, 26 December 2010 (UTC)

You inspired me to break this article into subsections. :) Serendi^podous 23:47, 27 December 2010 (UTC)

Really cool article. My suggestions are: The colors could be a little lighter. I would stick to normal scientific notation instead of multiple "to the power of" notation. It would be interesting to add:

• Next magnetic field reversal
• Earths outer core solidifies --> Magnetic field collapses --> Solar wind erosion of earth's atmosphere
• Time span at which radio isotope decay in the crust and make atomic bombs impossible and later nuclear power plants impossible.--Tobias1984 (talk) 19:56, 19 December 2011 (UTC)

I would also move the box explaining the colors under the headline. Cheers. --Tobias1984 (talk) 20:02, 19 December 2011 (UTC)

Magnetic field reversals aren't predictable, so no one knows when the next one will start. Will need to look into the others, but they're really good suggestions. :) Serendi^podous 23:38, 19 December 2011 (UTC)

I roughly calculated (Volume Earth)(Fraction Crust)(Fraction Continental Crust)(Mean Density Continental Crust) = (Mass Continental Crust) and then (Mass Continental Crust)(Abundance of U235) = (Mass U235 in Continental Crust). You need 56 kg of U235 of 85 % purity to achieve spherical critial mass (Uranium-235) so actually only 47.6 kg. I estimated that after 32 half-lifes your left with 34 kg. That would take about 1.8*10^44 years. Can anyone confirm this or offer a more accurate value?--Tobias1984 (talk) 19:06, 20 December 2011 (UTC)

I also thought of some possible biological events. Edward Wilson estimates that 27000 species go extinc every year (When will all species have gone extinct?)(Source: Edward Wilson 1992: The Diversity of Life). Another "fun fact" would be the time it would take for evolution to try out every possible combination of DNA. I think there was something about that in Richard Dawkins' (River out of Eden) or Daniel Dennet's (Darwin's Dangerous idea). --Tobias1984 (talk) 19:22, 20 December 2011 (UTC)

Black dwarf

Per the following reference:

Vila, Samuel C. (1971), "Evolution of a 0.6 M_{sun} White Dwarf", Astrophysical Journal, 170: 153, Bibcode:1971ApJ...170..153V, doi:10.1086/151196 {{citation}}: Unknown parameter |month= ignored (help)

once a star similar to the Sun becomes a white dwarf, it should cool and crystallize to become a black dwarf some seven billion years later. (Per Table 2, it looks like the author's criteria for "becoming invisible" is when the luminosity falls to 0.000003 solar and the effective temperature drops to 2239 K.) Regards, RJH (talk) 03:50, 4 January 2012 (UTC)

Thanks! Added. Serendi^podous 10:05, 4 January 2012 (UTC)

Color coding scheme

One of the issues raised during the FL review was the color coding scheme. Might I suggest something similar but perhaps clearer and less colorful? The following sample schema uses a color/icon column for categorization rather than colorizing the entire row and using a typographical symbol. I tried an atomic symbol for the physics rows, but it didn't display as well as the psi from quantum mechanics.

	Years from now	Event
	36,000	Ross 248 passes between 3.024 light years of Earth, becoming the Sun's closest star.
	50,000	According to the work of Burger and Loutre, at this time the current interglacial ends, sending the Earth back into an ice age, assuming limited effects of anthropogenic global warming. Niagara Falls erodes away the remaining 20 miles to Lake Erie and ceases to exist.
	100,000	The hypergiant star VY Canis Majoris will have likely exploded in a hypernova.
	250,000	Lo'ihi, the youngest volcano in the Hawaiian-Emperor seamount chain, will rise above the surface of the ocean and become a new volcanic island.
	2×1036	The estimated time for all nucleons in the observable Universe to decay, if the proton half-life takes its smallest possible value (8.2 x 1033 years).
	3×1043	Estimated time for all nucleons in the observable Universe to decay, if the proton half-life takes the largest possible value, 1041 years, assuming that the Big Bang was inflationary and that the same process that made baryons predominate over anti-baryons in the early Universe makes protons decay. By this time, if protons do decay, the Black Hole Era, in which black holes are the only remaining celestial objects, begins.
	$10^{10^{10^{10^{2.08}}}}$	Scale of an estimated Poincaré recurrence time for the quantum state of a hypothetical box containing a black hole with the mass within the presently visible region of the Universe.
	$10^{10^{10^{10^{10^{1.1}}}}}$	Scale of an estimated Poincaré recurrence time for the quantum state of a hypothetical box containing a black hole with the estimated mass of the entire Universe, observable or not, assuming Linde's chaotic inflationary model with an inflation whose mass is 10−6 Planck masses.

Regards, RJH (talk) 22:34, 27 March 2012 (UTC)

Would anybody object if I implemented this? Regards, RJH (talk) 19:34, 29 March 2012 (UTC)

I have no problem with it. Serendi^podous 22:31, 29 March 2012 (UTC)

Thank you. I've implemented the change. Regards, RJH (talk) 02:01, 30 March 2012 (UTC)

I think we need to add an explanation for the "Man" key now. Serendi^podous 07:57, 30 March 2012 (UTC)

Done. Might I add that the list would probably be much easier to maintain and edit if WP:LDR were applied. Thanks. Regards, RJH (talk) 14:38, 30 March 2012 (UTC)

Problem with statement

I tried to correct the following statement, only to see it reverted:

This marks the transition from the Stelliferous Era to the Degenerate Era; the time during which all stars slowly exhaust their fuel and die

The issue is that this is happening right now: all stars have been exhausting their fuel and dying ever since the first star was formed. It needs to capture the fact that no new stars are being formed. Regards, RJH (talk) 15:34, 6 April 2012 (UTC)

"have exhausted their fuel" implies that they've already exhausted their fuel, rather than are no longer being born. Will attempt a rephrase.Serendi^podous 15:38, 6 April 2012 (UTC)

Well I look at the order of magnitude of 100 trillion years for the transition point, and even a red dwarf is going to exhaust its fuel in much less time than that. Hence it's kind of splitting hairs. But thanks. Regards, RJH (talk) 16:05, 6 April 2012 (UTC)

Survivors

Some scientists have speculated that some animals, such as snakes, scorpions and spiders might still be around in a billion years. Should that be added to the article? Source below.

http://www.youtube.com/watch?v=R7fK_AHT_uE

great info, but we can't use youtube as a source. Tracking down the scientists cited in the documentary and their papers could be a good idea. Serendi^podous 07:18, 12 April 2012 (UTC)

I might look for some papers. And many people seem to forget that even after the extinction of plants, algae and lichens would still be supplying oxygen. — Preceding unsigned comment added by 101.98.128.11 (talk) 08:11, 12 April 2012 (UTC)

Really? Do algae use a different type of photosynthesis than other plants? Serendi^podous 08:14, 12 April 2012 (UTC)

I couldn't find any papers. And by algae I meant things like red algae, microbial algae and the algae that forms pond slime. Not kelp or seaweed. — Preceding unsigned comment added by 101.98.128.11 (talk) 08:28, 12 April 2012 (UTC)

And algae aren't plants. — Preceding unsigned comment added by 101.98.128.11 (talk) 08:30, 12 April 2012 (UTC)

There is some coverage of this topic here: Future of the Earth#Climate impact (including references). Regards, RJH (talk) 16:29, 12 April 2012 (UTC)

Added. Thanks for bringing it up. Serendi^podous 08:25, 13 April 2012 (UTC)

Logorithmic timeline

One of the deal breakers for this at FL was the absence of a logarithmic timeline. I have issues with such a creation because a) logarithmic timelines are misleading to anyone who doesn't know how they work and b) no logorithmic timeline could cover the entire list. However, a shortened logorithmic timeline may be possible, say from 10⁴ to 10¹⁵. It might even be extended to a "double decker" format with a second timeline at the bottom going from 10¹⁰ to 10¹⁰⁰, increasing by 10¹⁰ each time. Perhaps the 6000 years of human history could be added to scale in the 10¹ to 10³ slot, while the entire span of the upper timeline could then be added to scale in the lower timeline. I dunno. It would probably be very crowded. However, I have neither the software nor the knowhow to test such an idea. Is anyone interested? Serendi^podous 08:25, 13 April 2012 (UTC)

It shouldn't be too difficult to do in an svg drawing, but, as you say, it may become crowded. Just including selected highlights could clean it up quite a bit, plus we wouldn't need to keep updating the graphic every time there was a new addition.

The Inkscape tool is freely available, or I can give it a go. I don't think Inkscape has a logarithmic capability, so it would have to be done by calculating the appropriate coordinates. It's also possible that the free spreadsheet tool in OpenOffice (StarOffice) may include logarithmic graphing capability. Regards, RJH (talk) 16:24, 13 April 2012 (UTC)

Earth-Moon tidelock

I was wondering, should that belong to the "Future of the Earth" section or to the "astronomical events" section? Serendi^podous 19:08, 18 April 2012 (UTC)

I'm not sure. Based upon its definition, the "Astronomical events" section seems to include a number of events that probably belong in the earlier chart. The split between the two seems a little fuzzy. Maybe the "Astronomical events" table should be limited to rare but recurring events? Regards, RJH (talk) 21:09, 18 April 2012 (UTC)

I've shifted a few up. Let me know if that's OK. Serendi^podous 07:39, 19 April 2012 (UTC)

It seems fine to me. The one entry I have a concern with is "Median point at which tidal interaction with the Moon makes Earth's axial tilt impossible to calculate." My present understanding is that the situation is actually a lot worse than it is described here because the Earth's axial tilt could become chaotic, with the poles migrating through large angles over time scales of a few million years. There is some more information here. Thanks. Regards, RJH (talk) 16:43, 19 April 2012 (UTC)

OK, I've had a go at revising it. Serendi^podous 06:41, 20 April 2012 (UTC)

I've been thinking of adding this note

$10^{10^{26}}$ is 1 followed by 10²⁶ (100 sextillion) zeroes. Beyond this point, although years are used for convenience, such numbers would be the same if measured in nanoseconds or ages of the Universe

What do you think? Is it worth adding? Serendi^podous 16:50, 6 April 2012 (UTC)

Sure, why not? At that point it's more of a mathematical curiosity than anything we can realistically grasp. Regards, RJH (talk) 19:06, 6 April 2012 (UTC)

Can you add a link/reference for this statement? I think I understand the idea but I am not sure. How can two different numbers be the same? DouglasCalvert (talk) 01:39, 7 May 2012 (UTC)

There isn't really a way to specifically source it; it's just a consequence of the math.

Here's how it works:

$10^{10^{26}}$ is 1 followed by 100 septillion zeroes; $10^{10^{25}}$ is one followed by 10 septillion zeroes, while $10^{10^{27}}$ is one followed by 1 octillion zeroes. So in order to go from $10^{10^{26}}$ to $10^{10^{25}}$, you have to take away 90 septillion zeroes, and in order to go from $10^{10^{26}}$ to $10^{10^{27}}$ you have add on 900 septillion zeroes.

The shortest possible length of time is the Planck time; it is the time it takes light to travel the shortest distance defined by physics, the Planck length. You could conceivably divide the Planck time into centiplancks and milliplancks, but there would be no point, because there would be nothing to measure with them. The Planck time is roughly 5.39x10^-44 seconds. To put that in perspective, a nanosecond is 10^-9 seconds. There are (roughly) 5.85x10⁵⁰ (that's 585 with 48 zeroes after it) Planck times in a year. For ease's sake, let's round up and say 10⁵¹. So to express $10^{10^{26}}$ years in Planck times, we add on 51 zeroes.

Conversely, the largest timespan (at least that I'm aware of) is the lifespan of a supermassive black hole with a mass of 20 trillion Suns. It is (again roughly) 1.7 x10¹⁰⁶ years (that's 17 with 105 zeroes after it, or 1.7 million googol, in layman's terms), which means to express $10^{10^{26}}$ years in those units, we take away 106 zeroes.

OK. Now, compare adding 51 zeroes to adding 900 septillion zeroes, or taking away 106 zeroes to taking away 90 septillion zeroes, and you begin to see how units become somewhat irellevant when dealing with multiple exponents. Serendi^podous 13:20, 7 May 2012 (UTC)

Okay, that is what I was thinking. I would like to suggest changing it to "essentially be the same numbers." I realize this a pedantic complaint but encyclopedic content should be pedantic... DouglasCalvert (talk) 21:58, 7 May 2012 (UTC)

I might do that (I've been thinking about it), but I don't want to give the impression that the number would ever change. It would be the same number. It's just such a large number that it encompasses our entire concept of reality in its error bars. Serendi^podous 22:18, 7 May 2012 (UTC)

The mathematically pedantic term would be "the same order of magnitude". Regards, RJH (talk) 22:38, 7 May 2012 (UTC)

OK, I've slept on it, and I think I've figured it out. Serendi^podous 07:50, 8 May 2012 (UTC)

White dwarf entry

The estimated date in the entry for the Sun becoming a white dwarf may be incorrect. The Schroder and Connon Smith (2008) paper shows the Sun still being in the red giant stage at that point. Regards, RJH (talk) 21:11, 18 April 2012 (UTC)

I applied a correction. Hope its okay. Regards, RJH (talk) 02:31, 19 April 2012 (UTC)

The timeframes at a certain point become rounding errors. Unless you were several orders of magnitude wrong.  :) SkepticalRaptor (talk) 23:35, 7 May 2012 (UTC)

One billion years from now

It says that the surface temperature will reach 47ºC and the "oceans will boil away." Does this mean that water boils at 47ºC sometime in the future? Or is there some sort of error. I'll admit that's hot, but I have actually walked a couple of miles in that temperature, and I didn't see any water boil away.  :) So, either the temperature is wrong, physics has changed, or the oceans will still be there. Any ideas? SkepticalRaptor (talk) 23:47, 7 May 2012 (UTC)

That's the temperature where the planet is expected to enter a moist greenhouse phase, leading to runaway evaporation of the oceans. I.e. it's a trigger point. Regards, RJH (talk) 00:22, 8 May 2012 (UTC)

Hmmmm. But I stand by my concern. Water doesn't boil at 47ºC, and the article doesn't make your point, so it's terribly misleading/confusing. SkepticalRaptor (talk) 02:33, 8 May 2012 (UTC)

True enough. I modified the text by borrowing some wording from the Future of the Earth article. Is that any better? RJH (talk) 13:15, 8 May 2012 (UTC)

Reads much better. Actually pointed to this article on some reddit question about what would happen to the earth if the sun disappeared suddenly. BTW, I don't think I would want to live near the poles on this version of earth, even if there was water. SkepticalRaptor (talk) 00:43, 23 May 2012 (UTC)

Timeline for the interaction between Milky Way and Andromeda

Something seems amiss with this entry. The simulations in Cox & Loeb (2007) shows the close interaction occurring 3 Gyr from now, rather than the 7 Gyr listed in this article. The Andromeda–Milky Way collision article says 3–5 Gyr from now. Regards, RJH (talk) 17:56, 11 May 2012 (UTC)

Okaaay... that was a dumb mistake. I used the timeline in Formation and evolution of the Solar System as my reference point, but forgot that that timeline counts from the beginning of the Solar System, not from now. So yeah. Well caught. Serendi^podous 18:12, 11 May 2012 (UTC)

Thanks. Regards, RJH (talk) 19:03, 11 May 2012 (UTC)

Don Page citation not mainstream physics

Hi, I'm concerned that the citation on the Poincare recurrence time in the far future (ref. 64) from the article by Don Page is not mainstream physics. For example, almost all citations to that paper are from his own work, and not widely accepted. Can I remove the material? 18.111.68.138 (talk) 01:05, 20 May 2012 (UTC)

If the source is dubious, I'd rather find an alternate source for that material first. Or rather, I'd rather someone else did, because I have no idea how to verify such information. Serendi^podous 08:52, 20 May 2012 (UTC)

Does the last entry citing Done Page imply that the universe is likely to return to it's current state in 10^10^10^10^10^1.1 years (or Planck times, or multiples of the age of the universe)? Or is this only valid for a closed universe? — Preceding unsigned comment added by Deathmare (talk • contribs) 15:43, 8 July 2012 (UTC)

I read it as a probability statement about random quantum fluctuations creating a state that matches the currently state of the observable universe. In that sense it's an average for what's essentially a mathematical exercise. There's no way to know if it has any bearing on reality. I'm not even clear that the preconditions of the Poincaré recurrence theorem apply to the Universe. Does the phase state apply to a non-discrete space? Is space discrete at the Planck scale or continuous? Shrug.

If we can't resolve the concerns with this topic, perhaps we should just convert it into a "See also" link to the Poincaré recurrence theorem article? Regards, RJH (talk) 17:59, 8 July 2012 (UTC)

Roger Penrose appears to endorse a similar idea. But this is all a bit above my head, so I'm not sure how to work it in. Serendi^podous 21:16, 8 July 2012 (UTC)

Images

Have any use for more like this one?

File:NASA's Hubble Shows Milky Way is Destined for Head-on Collision with Andromeda Galaxy.tif

Four billion years from now when we collide. Feel free to remove image after viewing.--Canoe1967 (talk) 19:48, 6 June 2012 (UTC)

It's been nom'd for deletion; we may want to await the outcome first. Regards, RJH (talk) 00:35, 15 June 2012 (UTC)

My fault. I thought it could stay, but had to flip-flop after I read the fine print of the site. We may be able to upload it to commons under fair use an historical image, but I don't know if future history counts.--Canoe1967 (talk) 00:42, 15 June 2012 (UTC)

I found a video that you may like as well.--Canoe1967 (talk) 20:51, 18 June 2012 (UTC)

Big bang in the far future

Regarding this statement:

The Universe's expansion causes all evidence of the Big Bang to disappear beyond the practical observational limit, rendering cosmology impossible

there's an alternative approach listed here:

http://www.cfa.harvard.edu/news/2011/pr201111.html

http://arxiv.org/abs/1102.0007

There are some other nuggets of information in that paper may be of interest, such as the time scale for wavelength of the CMB photons to exceed the size of the observable universe. Regards, RJH (talk) 00:31, 15 June 2012 (UTC)

There are some contradictions there. The source for this article

http://arxiv.org/pdf/astro-ph/9902189v1.pdf

says that all evidence will have moved beyond our local supercluster in 2 trillion years, whereas the arxive source above

http://arxiv.org/pdf/1102.0007v2.pdf

says that all evidence will have moved beyond the local group within just 150 billion years. There must be a way to reconcile this. Serendi^podous 10:21, 15 June 2012 (UTC)

Unless I'm mistaken, I believe the 150 billion year value comes from the first reference. The author uses that time interval to deduce the net 2 trillion year estimate. The latter reference says that "Within ∼ 10¹¹ [100 trillion] yr after the Big Bang, all galaxies outside the Local Group will exit from our event horizon", which is consistent with the first since it is a much smaller region and a much longer time interval. Regards, RJH (talk) 18:43, 15 June 2012 (UTC)

10¹¹ is 100 billion, not 100 trillion. Serendi^podous 07:14, 16 June 2012 (UTC)

Aye, you're correct. Regards, RJH (talk) 14:55, 16 June 2012 (UTC)

So which do we choose? Serendi^podous 16:14, 16 June 2012 (UTC)

Well personally I'd lean toward the more recent paper since it uses the latest data and appears better referenced. But it might be better to ask at Wikipedia talk:WikiProject Astronomy. Regards, RJH (talk) 16:36, 16 June 2012 (UTC)

Well, posting on the WP page is only slightly less helpful than placing a message in a bottle, so I think I'll go with your first suggestion :-) Serendi^podous 18:11, 16 June 2012 (UTC)

It's not unheard of to get useful responses from that WikiProject, although sometimes it takes a little time. Shrug. Regards, RJH (talk) 23:03, 16 June 2012 (UTC)

Issues with footnotes

I just wanted to note that the citations will likely need some housekeeping done to make them consistent enough for FA promotion, if that is still the goal. Some concerns:

• Inconsistent case usage among cited article titles. For example:
  • "Mars: A Warmer, Wetter Planet": all caps
  • "Climate: An exceptionally long interglacial ahead?": caps at start
  • "Theoretical Formulation of the Phobos, moon of Mars, rate of altitudinal loss": oddly mixed caps
• "Berger A, Loutre MF": name format
• "The Last Gasps of VY Canis Majoris: Aperture Synthesis and Adaptive Optics Imagery": missing authors
• "Nelson, Prof. Stephen A..": why the "Prof." title?
• Not clear if semicolon separators or comma and/& is the norm for the author listings:
  • Neron de Surgey, O. and Laskar, J.
  • Murray, C.D. & Dermott, S.F.
  • Adams, Fred and Laughlin, Greg
  • Meeus, J. and Vitagliano, A.
  • Saxena, Ashutosh and Sanjay, Rawat
• "Plait, Phil (2002). Bad Astronomy. Wiley. pp. 55-56.": looks incomplete. Is there a URL available?
• "Astronomy Answers: Modern Calendars". University of Utrecht. 2010. Retrieved 2011-09-14.: looks incomplete.

&c. Thank you. Regards, RJH (talk) 03:23, 30 June 2012 (UTC)

I've revised the issues you raised, except the last one, because the site is temporarily down. Serendi^podous 07:33, 30 June 2012 (UTC)

Thank you. Regards, RJH (talk) 15:28, 30 June 2012 (UTC)

Recent vandalism

This page has become popular due to recent vandalism posted by a Reddit user on r/gaming. I would recommend the page be locked from editing until its popularity blows over. http://www.reddit.com/r/gaming/comments/w2rz7/and_then_it_was_released/ 184.19.28.100 (talk) 18:40, 5 July 2012 (UTC)

Not sure what brought all that on, but I put in a request for semiprotection. Once that's in place we can sweep up the droppings. Regards, RJH (talk) 19:02, 5 July 2012 (UTC)

The exponent note

People are really having trouble understanding it. I'm wondering if it is too abstract to be useful. Serendi^podous 08:33, 6 July 2012 (UTC)

Could be. I'd guess that the values with exponents to exponents are probably hard to grasp; the scale is certainly difficult to even comprehend. Regards, RJH (talk) 14:41, 6 July 2012 (UTC)

Triton and the Roche limit

Here's another possible addition:

Chyba, C. F.; Jankowski, D. G.; Nicholson, P. D. (1989), "Tidal evolution in the Neptune-Triton system", Astronomy and Astrophysics, 219 (1–2): L23–L26, Bibcode:1989A&A...219L..23C {{citation}}: Unknown parameter |month= ignored (help)

Once it reaches the Roche limit, part of the remains should form a ring system like Saturn's. Regards, RJH (talk) 00:57, 10 July 2012 (UTC)

already in the article. :-) Serendi^podous 18:48, 12 July 2012 (UTC)

Ah. Sorry, I missed that. Regards, RJH (talk) 19:20, 12 July 2012 (UTC)

Future CMB temperature

This source predicts that in 150 Ga (from the Big Bang), the CMB temperature will be 0.3 K and essentially undetectable. Still trying to find a ref. for when it will be 60 nanokelvin (6 × 10^–8 K); the temperature of a one solar mass black hole. It's easy enough to compute, but that would be OR. Regards, RJH (talk) 22:47, 13 July 2012 (UTC)

I'd need to be clear on one thing before I added it; what is the difference between temperature and wavelength? Because we already have wavelength listed and we don't want to confuse people. Serendi^podous 22:51, 15 July 2012 (UTC)

Since the CMB is a near perfect black body, I believe the temperature and peak wavelength are related by Wien's displacement law. The 10²⁹ value in the list likely is a reference to the wavelength exceeding the size of the observable universe, in which case it would be completely undetectable. The above limitation is perhaps a more practical constraint of reduced energy emission. Regards, RJH (talk) 00:01, 16 July 2012 (UTC)

Let me see if I understand: the temperature shows when the CMB will be undetectable with current technology, and the wavelength data is when it will not be detectable at all. Is that right? Serendi^podous 21:29, 19 July 2012 (UTC)

That sounds like a good way to put it, yes. Wording it in terms of present day technology would put it in perspective, even though humans probably won't be around by then. Regards, RJH (talk) 22:31, 19 July 2012 (UTC)

Sorry to keep pushing this, but do you have a page number? Serendi^podous 07:28, 20 July 2012 (UTC)

Sure: 210. It's usually in the 'pg=' field of the Google books query. Regards, RJH (talk) 15:10, 20 July 2012 (UTC)

… halfway through the precessional cycle, Earth's axial tilt will be reversed, causing summer in the northern hemisphere to occur in December …

Of course, it is not true. Because the definition of tropical year (the year unit in most calendars) is centred on equinoxes (or solstices), an influence of the axial precession to seasons is accounted for. Because some half-educated air-monger managed to put his thoughts on a printed paper, his invention now pollutes Wikipedia. What references should we provide to throw it away legitimately? Incnis Mrsi (talk) 17:36, 22 July 2012 (UTC)

The half-educated air-monger is Phil Plait, an astronomer who worked on Hubble. The fault was mine; I misinterpreted what he said. Serendi^podous 17:40, 22 July 2012 (UTC)

On the other hand, there can be noticeable climactic influences caused by the alignment of the perihelion with the boreal summer season.[1] Regards, RJH (talk) 18:47, 22 July 2012 (UTC)

On the hand other than which? The Sun is in Sagittarius at Earth's perihelion. The Sun, likely, will remain in Sagittarius at Earth's perihelion for a million years. It is correct to say: "the boreal summer season will align with the perihelion". It is correct to say: "the Sun will pass through Sagittarius during the boreal summer season". What was incorrect it's to assume that the month when the Sun passes through Sagittarius will bear the name "December" forever. Incnis Mrsi (talk) 19:10, 22 July 2012 (UTC)

Which is fine. This article covers much longer time intervals. Regards, RJH (talk) 21:25, 22 July 2012 (UTC)

Earth's elliptical orbit is not fixed in inertial space. It precesses (advances) about 11.6" per Julian year in the direction of Earth's motion within its orbit (+11612.35290"t [Julian millennia] in $\varpi$ in § 5.8.3 on p. 675 of [2]). Its perihelion will return to its present position in about 112,000 years (1296000/11.6), thus the direction in inertial space of its perihelion and aphelion will swap in 56,000 years. This apsidal precession is primarily caused by the gravitational perturbations on Earth of Venus and Jupiter (d$\pi$/dt on p. 180 of [3]). The general precession of Earth's rotational axis is about 50.3" per Julian year. Their sum, 61.9", causes the equinoxes and solstices to revolve once around Earth's elliptical orbit in about 21,000 years. So the vernal equinox will be on the opposite side of Earth's precessing orbit in about 10,500 years. See A year on Earth, This restless globe and The Seasons and the Earth's Orbit by USNO among others. Furthermore, Vega does not become the pole star at 13,000 years, but a little more, at about 14,000 years (A year on Earth and Axial precession#Changing pole stars). — Joe Kress (talk) 06:39, 23 July 2012 (UTC)

Thanks. Talk pages are great, at least more useful than . Why these valuable thoughts did not yet find the way to Earth's orbit article? Incnis Mrsi (talk) 08:39, 23 July 2012 (UTC)

I'm sure the Axial precession article could be improved upon, if that is your interest. Thanks. Regards, RJH (talk) 13:39, 23 July 2012 (UTC)

"All life on Earth dies"

This isn't an absolute certainty, per:

Li, King-Fai; Pahlevan, Kaveh; Kirschvink, Joseph L.; Yung, Yuk L. (June 16, 2009), "Atmospheric pressure as a natural climate regulator for a terrestrial planet with a biosphere", Proceedings of the National Academy of Sciences, 106 (24): 9576–9579, Bibcode:2009PNAS..106.9576L, doi:10.1073/pnas.0809436106, PMC 2701016, PMID 19487662

You might want to make this a low end of the time estimate. Regards, RJH (talk) 15:11, 31 July 2012 (UTC)

Thanks for that. Added. :-) Serendi^podous 11:20, 1 August 2012 (UTC)