# How long will life on this planet be possible for in your estimation? **URL:** \ **Category:** Great Debates\ **Created:** [January 29, 2024, 1:05pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808 "2024-01-29T13:05:36Z")\ **Posts on this page:** 16\ **Page:** 3
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [February 2, 2024, 3:20pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/41 "2024-02-02T15:20:25Z")
> [@eburacum45](#): > > Have you never heard of C4 carbon fixation? That’s good down to about 10ppm, and evolution is pointing that way. Without human intervention, many plants will adapt to lower CO2 levels. > > With human intervention, either the CO2 levels will be artificially raised by burning kerogen, or more plants will be genetically engineered to tolerate low CO2. Or both. I am only slightly familiar with c4 fixation. I do agree with you that plant life will evolve that way. The transition would likely take place over several million years. Fascinating study here. It seems it would favor grasslands and things like corn and other grains. Acacia trees also employ this and interestingly the acacia family is also good at fixing nitrogen. I do plan to read on this more. ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [February 2, 2024, 6:24pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/42 "2024-02-02T18:24:34Z")
**Warning for** **HoneyBadgerDC** As the third flagger put it: > “Humans absolutely need to spew carbon dioxide to save the planet” definitely counts as climate change misinformation. Nobody would be spreading that lie, if not for the fact that they want to score points on the climate change debate. Seeing your additional replies, I agree. We will probably bump this up to the Modloop to talk about a suspension for you trying to work around your topic ban and hijack yet another thread with misinformation. You are probably becoming too much of a problem. I suggest you watch what you post a lot more carefully. * * * **You are banned from this thread. Do not post in it again.** ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [February 5, 2024, 5:05am UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/43 "2024-02-05T05:05:44Z")
> **[futurebiosphereextinctionsFranck.pdf](https://www.vanderbilt.edu/olli/class-materials/futurebiosphereextinctionsFranck.pdf)** > Complex multicellular life becomes extinct in about 1.2 Gyr and eucaryotes in about 1.5 Gyr. In both cases the ultimate life span of the biosphere, i.e. the extinction of procaryotes, ends at about 1.6 Gyr. I personally think humanity or whatever descendants we have will outlive this due to interstellar travel. Something intelligent descended from humans will probably be around for quintillions of years. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [February 20, 2024, 6:45am UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/44 "2024-02-20T06:45:00Z")
I got a lot of shit on my plate. Don’t rush me! ---
**Author:** ![Steven\_Maven](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steven_maven/32/3272_2.png) [@Steven\_Maven](https://boards.straightdope.com/u/Steven_Maven)\ **Post date:** [March 28, 2024, 1:56am UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/45 "2024-03-28T01:56:29Z")
> [@robby](#): > > From memory, the time frame for the expansion of the Sun into a red giant is around 5 billion years from now, but the oceans will boil around 1 billion years from now. I looked this up last week. You are correct. ---
**Author:** ![philipdalton](https://avatars.discourse-cdn.com/v4/letter/p/85e7bf/32.png) [@philipdalton](https://boards.straightdope.com/u/philipdalton)\ **Post date:** [March 29, 2024, 6:11pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/46 "2024-03-29T18:11:12Z")
Does anyone think aliens could in actual fact be other species which descended from us in the distant future of this planet, left Earth due to it becoming uninhabitable and then learned how to travel through time and space so that they could back here again? ---
**Author:** ![philipdalton](https://avatars.discourse-cdn.com/v4/letter/p/85e7bf/32.png) [@philipdalton](https://boards.straightdope.com/u/philipdalton)\ **Post date:** [March 29, 2024, 6:21pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/47 "2024-03-29T18:21:00Z")
Does anyone think aliens could in actual fact be other species which descended from us in the distant future of this planet, left Earth due to it becoming uninhabitable and then learned how to travel through time and space so that they could back here again? [/quote] ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [March 29, 2024, 6:43pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/48 "2024-03-29T18:43:41Z")
> [@philipdalton](#): > > Does anyone think aliens could in actual fact be other species which descended from us in the distant future of this planet, left Earth due to it becoming uninhabitable and then learned how to travel through time and space so that they could back here again? No. . ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [March 29, 2024, 8:05pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/49 "2024-03-29T20:05:13Z")
> [@philipdalton](#): > > Does anyone think aliens could in actual fact be other species which descended from us in the distant future of this planet, left Earth due to it becoming uninhabitable and then learned how to travel through time and space so that they could back here again? No. Not that’s absolutely, positively, invariably impossible. But it makes no more sense than any idea based on the total lack of evidence that intelligent aliens exist anywhere in the universe much less as visitors to earth. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [March 29, 2024, 10:04pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/50 "2024-03-29T22:04:28Z")
No; but you could possibly make an interesting story out of it, presuming that you were willing to handwave pretty much all of known science. A number of interesting stories do, though. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [March 31, 2024, 12:17am UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/51 "2024-03-31T00:17:07Z")
> [@Peter\_Morris](#): > > > [@philipdalton](#): > > > > Does anyone think aliens could in actual fact be other species which descended from us in the distant future of this planet, left Earth due to it becoming uninhabitable and then learned how to travel through time and space so that they could back here again? > > No. > > . I’d rephrase that reply just a bit. How about > Nobody with any sense or actual knowledge of the relevant scientific facts thinks that. > > There are almost certainly ignorant corners of wackiness on the internet where goofballs gather to propound such silliness. But they can (and should) be laughed at and ignored. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [March 31, 2024, 1:53am UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/52 "2024-03-31T01:53:30Z")
I prefer mine. ---
**Author:** ![The\_Other\_Waldo\_Pepper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_other_waldo_pepper/32/12370_2.png) [@The\_Other\_Waldo\_Pepper](https://boards.straightdope.com/u/The_Other_Waldo_Pepper)\ **Post date:** [April 2, 2024, 12:58pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/53 "2024-04-02T12:58:08Z")
> [@philipdalton](#): > > Does anyone think aliens could in actual fact be other species which descended from us in the distant future of this planet, left Earth due to it becoming uninhabitable and then learned how to travel through time and space so that they could back here again? Wait, so Jor-El was actually building a time machine? ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [April 2, 2024, 1:07pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/54 "2024-04-02T13:07:50Z")
> [@philipdalton](#): > > Does anyone think aliens could in actual fact be other species which descended from us in the distant future of this planet, left Earth due to it becoming uninhabitable and then learned how to travel through time and space so that they could back here again? This is a pretty old SciFi trope. One notable example is the Mind Flayer empire in D&D. In older editions’ lore, the mind flayers are these squid headed dudes that eat brains and have very powerful psionic magic. They are working to build an empire using people they enslave with their squid brain powers. They also eat the brains of these people. Eventually they will succeed in their mission, and build a world-spanning empire that lasts eons, until their slaves rebel against them and destroy the mind flayers almost entirely. But at the last moment, some of the mind flayers (and some of the rebelling slaves, inadvertently) send themselves back in time to the distant past, where they begin the work of secretely preparing to take over the world again. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 2, 2024, 2:17pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/55 "2024-04-02T14:17:34Z")
IOW > Sisy meet Phus; Phus meet Sisy. ---
**Author:** ![ParallelLines](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/parallellines/32/3575_2.png) [@ParallelLines](https://boards.straightdope.com/u/ParallelLines)\ **Post date:** [April 2, 2024, 4:49pm UTC](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808/56 "2024-04-02T16:49:46Z")
> [@Babale](#): > > This is a pretty old SciFi trope. Rather than list all the possible iterations of this, I’ll save myself the typing: > **[Time Travel - TV Tropes](https://tvtropes.org/pmwiki/pmwiki.php/Main/TimeTravel)** > > For related tropes, see Time Travel Tropes. Time travel is a very versatile plot device. It can range from simply a device for moving The Hero from one Adventure Town to another, to a driver of the plot in itself as the characters try to … The most recent and direct memory I have that parallels the OP is from Nu-Who, where the still apparently human descendants at the literal heat death of the universe come back to invade modern (circa the series) Earth in a endless paradox. It’s a trope, not a philosophy or subject of debate IMHO, because if they did, I agree, it’d be on the level of an invasion, not just a rare traveler on an empty road, especially if in said future they: > [@philipdalton](#): > > left Earth due to it becoming uninhabitable and then learned how to travel through time and space so that they could back here again? [Previous page](https://boards.straightdope.com/t/how-long-will-life-on-this-planet-be-possible-for-in-your-estimation/996808.md?page=2)