# Could life on Earth survive the far future?

• I

## Summary:

I'm not referring to climate change, but post Solar red giant phase.

## Main Question or Discussion Point

"Currently, the Moon is moving away from Earth at a rate of 4 cm (1.5 inches) per year. In 50 billion years, if the Earth and Moon are not engulfed by the Sun, they will become tidelocked into a larger, stable orbit, with each showing only one face to the other".

What is meant by "if' the Earth and moon are not engulfed by the Sun" by that time? Is there indeed a possibility that this this is not a future fate scenario for the Earth, and that this engulfment might not occur? It appears to be the case, because it continues:

"If Earth is not destroyed by the expanding red giant Sun in 7.6 billion years, then on a time scale of 1019 (10 quintillion) years the remaining planets in the Solar System will be ejected from the system by violent relaxation. If this does not occur to the Earth, the ultimate fate of the planet will be that it collides with the black dwarf Sun due to the decay of its orbit via gravitational radiation, in 1020 (Short Scale: 100 quintillion, Long Scale: 100 trillion) years."

So the Earth might either be ejected from the Solar System, or collide with the (black dwarf) Sun. Those are two very opposing future prospects for the Earth. The ejection scenario even implies that life on Earth could perhaps survive the future. That idea really astonished me, because I've always thought that, no matter what future scenarios will play out, one thing is for sure: the Sun wil engulf the Earth. The photosphere of the Sun is 5700 kelvin, hotter than any known element or alloy can remain solid at, so all life on Earth will, at some point, eventually, die out.

My question therefore is: could life on Earth survive the far future?

qraal

Related Astronomy and Astrophysics News on Phys.org
BvU
Homework Helper
2019 Award
No. But no reason to start packing anytime soon.

No

Ibix
The article isn't wrong, precisely (at least conceptually - I haven't checked its numbers). However, you shouldn't take it as literally as it is written - unfortunately.

We die when the Sun expands. But if we were orbiting something of the same mass that wouldn't expand (e.g. a solar mass black hole), we'd have time to tidal lock with the Moon. Etcetera etcetera. Essentially they are doing a set of independent calculations of how long each effect would take to kill us - the quickest one actually kills us.

Edit: kind of like a castaway calculating how long it'll take to starve to death and how long it'll take to die of thirst. There's nothing wrong with calculating how long he can survive without food, even if it's pointless because he'll dehydrate in a much shorter timeframe.

Last edited:
stefan r and BvU
Staff Emeritus
2019 Award
What is meant by "if' the Earth and moon are not engulfed by the Sun" by that time? Is there indeed a possibility that this this is not a future fate scenario for the Earth, and that this engulfment might not occur?
It's as correct and as incorrect as "If water froze at 60C there could be ice skating all year long."

It's as correct and as incorrect as "If water froze at 60C there could be ice skating all year long."
I understand what you mean, but why would anyone start an argument with a false premise?

Could you explain to me why the articles begins a sentence with a supposed probability, namely:
"If Earth is not destroyed by the expanding red giant Sun in 7.6 billion years...",
while, if I understand you correctly, that scenario is, with a 100% certainty, completely ruled out, and totally out the question?

It's quite misleading, don't you think?

Last edited:
Ibix
It's quite misleading, don't you think?
Welcome to Wikipedia.

Last edited:
BvU
Homework Helper
2019 Award
I understand what you mean, but why would anyone start an argument with a false premise?

Could you explain to me why the articles begins a sentence with a supposed probability, namely:
"If Earth is not destroyed by the expanding red giant Sun in 7.6 billion years...",
while, if I understand you correctly, that scenario is, with a 100% certainty, completely ruled out, and totally out the question?

It's quite misleading, don't you think?
Politicians are not supposed to answer "What if .. ? " questions. Physicsists do it all the time to find out what is the next biggest effect.

Pareto analysis comes to mind

Last edited:
I understand what you mean, but why would anyone start an argument with a false premise?
I don't see a false premise here. In the introduction of the Wikipedia page it clearly states:

Wikipedia said:
In about one billion years, the solar luminosity will be 10% higher than at present. This will cause the atmosphere to become a "moist greenhouse", resulting in a runaway evaporation of the oceans. As a likely consequence, plate tectonics will come to an end, and with them the entire carbon cycle.[13] Following this event, in about 2–3 billion years, the planet's magnetic dynamo may cease, causing the magnetosphere to decay and leading to an accelerated loss of volatiles from the outer atmosphere. Four billion years from now, the increase in the Earth's surface temperature will cause a runaway greenhouse effect, heating the surface enough to melt it. By that point, all life on the Earth will be extinct.[14][15] The most probable fate of the planet is absorption by the Sun in about 7.5 billion years, after the star has entered the red giant phase and expanded beyond the planet's current orbit.
Could you explain to me why the articles begins a sentence with a supposed probability, namely:
"If Earth is not destroyed by the expanding red giant Sun in 7.6 billion years...",
while, if I understand you correctly, that scenario is, with a 100% certainty, completely ruled out, and totally out the question?

It's quite misleading, don't you think?
Not really, I think you just misread what it says. You asked if life on Earth could survive the far future, but the quoted paragraph from Wikipedia is talking about the Earth already devoted of life.

Wikipedia said:
The most rapid part of the Sun's expansion into a red giant will occur during the final stages, when the Sun will be about 12 billion years old. It is likely to expand to swallow both Mercury and Venus, reaching a maximum radius of 1.2 AU (180,000,000 km). The Earth will interact tidally with the Sun's outer atmosphere, which would serve to decrease Earth's orbital radius. Drag from the chromosphere of the Sun would also reduce the Earth's orbit. These effects will act to counterbalance the effect of mass loss by the Sun, and the Earth will probably be engulfed by the Sun.
and then it follows:
Wikipedia said:
After fusing helium in its core to carbon, the Sun will begin to collapse again, evolving into a compact white dwarf star after ejecting its outer atmosphere as a planetary nebula. The predicted final mass is 54.1% of the present value, most likely consisting primarily of carbon and oxygen.[1]

Currently, the Moon is moving away from Earth at a rate of 4 cm (1.5 inches) per year. In 50 billion years, if the Earth and Moon are not engulfed by the Sun, they will become tidelocked into a larger, stable orbit, with each showing only one face to the other...[add rest of your quoted paragraph]
So the premise is if the Earth (and Moon) is not engulfed (destroyed) by the red giant Sun, but instead still a planetoid (which as I understand is still a posibillity). However life on this burnt out ball has been extinct for a long time.

PeroK
The most probable fate of the planet is absorption by the Sun in about 7.5 billion years
Doesn't "probable" imply that there is an alternative?

Freeman Dysan (to which the Wikipedia article is referring) here argues the following:
"The prevailing view (Weinberg, 1977) holds the future of open and closed
universes to be equally dismal. According to this view, we have only the
choice of being fried in a closed universe or frozen in an open one. The end
of the closed universe has been studied in detail by Rees (1969). Regrettably
I have to concur with Rees' verdict that in this case we have no escape from
frying. No matter how deep we burrow into the earth to shield ourselves from
the ever-increasing fury of the blue-shifted background radiation, we can only
postpone by a few million years our miserable end. I shall not discuss the
closed universe in detail, since it gives me a feeling of claustrophobia to
imagine our whole existence confined within the box (4). I only raise one
question which may offer us a thin chance of survival. Supposing that we
discover the universe to be naturally closed and doomed to collapse, is it
conceivable that by intelligent intervention, converting matter into radiation
and causing energy to flow purposefully on a cosmic scale, we could break open
a closed universe and change the topology of space-time so that only a part of
it would collapse and another part of it would expand forever? I do not know
the answer to this question. If it turns out that the universe is closed, we
shall still have about 10^10 years to explore the possibility of a
technological fix that would burst it open".

Is a Dyson sphere/swarm/net/shell something that is currently taken just as seriously by the scientific community as for instance something like Hawking radiation, or is it seen as fiction?

Staff Emeritus
2019 Award

The pessimistic future prospect. Should I stop trying to find credible and plausible optimistic scenarios?

Staff Emeritus
2019 Award
Yes, if you wish the answer were something else, you're welcome to try and fine one more to your liking. However, in the words of James McNeill Whistler, "Two and two continue to make four, in spite of the whine of the amateur for three, or the cry of the critic for five."

mark!, BvU and jim mcnamara
Ok, there are several issues with your understanding of the engulfment of the Earth/Moon system.

However the original statement you were reading was merely hypothetical and in now way indicative of options for the far future.

But back to my first statement. Firstly, the Sun will NOT passively engulf the Earth, based on current stellar evolution codes applied to the Sun. Instead, the Earth will raise tides in the very late phase of the Red Giant Sun and drag itself out of orbit.

Secondly, the Red Giant evolution of the Sun is dependent on the mass loss it will experience in its latter days as it's climbing the Red Giant Branch. If the opacity is actually higher, increasing the mass loss, then it's likely the Earth will survive. However frictional effects will make it a very near miss if it does.

Thirdly, the Red Giant Sun will have a significantly lower temperature than the present day Sun - that's one feature of its expansion. One can easily see why - the surface area it is radiating from will be much, much larger even though it will have a peak luminosity of ~2300 times the present. Peak radius will be about ~250 times the current, then the effective temperature will drop to <1/2 the present day. While ~2,500 K is hot, some materials will survive.

Of course, all the above depends heavily on whether the evolution of the Sun is left unmanaged by future intelligent life.

Summary:: I'm not referring to climate change, but post Solar red giant phase.

"Currently, the Moon is moving away from Earth at a rate of 4 cm (1.5 inches) per year. In 50 billion years, if the Earth and Moon are not engulfed by the Sun, they will become tidelocked into a larger, stable orbit, with each showing only one face to the other".

What is meant by "if' the Earth and moon are not engulfed by the Sun" by that time? Is there indeed a possibility that this this is not a future fate scenario for the Earth, and that this engulfment might not occur? It appears to be the case, because it continues:

"If Earth is not destroyed by the expanding red giant Sun in 7.6 billion years, then on a time scale of 1019 (10 quintillion) years the remaining planets in the Solar System will be ejected from the system by violent relaxation. If this does not occur to the Earth, the ultimate fate of the planet will be that it collides with the black dwarf Sun due to the decay of its orbit via gravitational radiation, in 1020 (Short Scale: 100 quintillion, Long Scale: 100 trillion) years."

So the Earth might either be ejected from the Solar System, or collide with the (black dwarf) Sun. Those are two very opposing future prospects for the Earth. The ejection scenario even implies that life on Earth could perhaps survive the future. That idea really astonished me, because I've always thought that, no matter what future scenarios will play out, one thing is for sure: the Sun wil engulf the Earth. The photosphere of the Sun is 5700 kelvin, hotter than any known element or alloy can remain solid at, so all life on Earth will, at some point, eventually, die out.

My question therefore is: could life on Earth survive the far future?

mark!
jim mcnamara
Mentor
@mark! let's look at your assumptions.
Ignoring projections of our sun's trip through a stellar lifetime:

The one assumption that seems to have the biggest problem is denying extinction.

You want our species to persist a billion years or maybe less, 500 million years.

So: let's see how our Earth has treated animals in general.

This site lists a very few animals and one bacterium. Forget the horsetails, too -- Plants. And ignoring the cyanobacteria leaves us with a few multicellular animals that have persisted. Since we are definitely not bacteria. The oldest is 700 million years.

Try this. it is interesting:
https://www.oldest.org/animals/species/

What happened to the billions of other species that are clearly not around anymore? They went extinct.

We are humans in the genus Homo.
Code:
Homo erectus.
Homo floresiensis.
Homo habilis.
Homo heidelbergensis.
Homo luzonensis.
Homo naledi.
Homo neanderthalensis.
Homo sapiens.  <- us
What happened to the other guys in the genus? They made fire, tools and probably had language. We even have some of their DNA in us today.

They went extinct.

Why posit that humans will not go extinct for a billion years? No other earthly multicellular organism has done that. The humans in the distant past went extinct too. No human species has made it longer than several hundred thousand years.

PS: at least two major extinction events are attributed to asteroid impacts. The others are attributed to plate tectonics and the formation of giant continents that wreck the climate or cause the Earth to become "snowball earth". Or worse, massive volcanic outpourings over thousands of years that wrecked the atmosphere. Or all three in one case, possibly. -- a really bad 100K+ years to be alive on earth.

See: https://en.wikipedia.org/wiki/List_of_extinction_events

Last edited:
Sanborn Chase and Klystron
Why posit that humans will not go extinct for a billion years?
Because we're not a branch of the evolutionary tree like all the other animals, we're more like its trunk.

Extremes die out and non extremes survive, in the sense that human health is limited by a very narrow range of dos and don'ts, and the same thing goes for the entire planet. Global homeostasis (think of the narrow temperature range, or salinity level) predicts that maintaining a balance ensures survival. So, in line of this progression, the human race won't go extinct altogether, although human (extreme) cultures will go extinct.

What happened to the other guys in the genus? They made fire, tools and probably had language. We even have some of their DNA in us today.

They went extinct.
You're referring to Homo Erectus. They didn't simply go extinct, they gave rise to Homo Sapiens. Members of the Homo Erectus lineage were our direct ancestors.

And ignoring the cyanobacteria leaves us with a few multicellular animals that have persisted.
We kind of still are, partly, because the eukaryotic cell is the result of the merger of two prokaryotes. (By the way, cyanobacteria are not multicellular. They make biofilms, colonies, which is very different from multicellularity).

These are just a few examples of evidence that gave reason to assume that our human, unbroken lineage since the Big Bang, is a trunk rather than a branch. Perhaps you're not convinced yet, but keep in mind that I'm not making a claim here, I'm only pointing out why your claim isn't necessarily the way we ought to look at evolution, so my line of reasoning that our lineage will continue to persist, isn't ruled out by your arguments, don't you agree? I don't think that the absence of more evidence on my side allows you to therefore claim that we're not like a trunk, but rather like a branch (which is essentially the basic assumption on which your reasoning is based). You're not showing me how/why this is supposedly the case.

So, without any evidence on your part to support that claim, it's hard for me to accept the pessimistic conclusion (i.e. inevitable extinction) that you're attaching to this line of reasoning.

Last edited:
weirdoguy and BvU
jim mcnamara
Mentor
No: Please do not make up baloney like this:
Because we're not a branch of the evolutionary tree like all the other animals, we're more like its trunk.
https://en.wikipedia.org/wiki/Primate
We are primates. Primates are a new branch, just 85 million years old, the very first mouse like primates arose back then. Our branch of the primates is the great apes, a new development during the Miocene (well after Dinosaurs)

BvU