r/RealisticFuturism

If we follow the most commonly accepted theory for the "end of the universe", heat death, the universe will last for approximately 10^100 years after the big bang.

Given this, the stelliferous era is estimated to last up to 10^14 years, or 100 trillion years. From my understanding, that means that the habitable period of the universe should also last that long, or at least somewhere in the ballpark of that.

The thing is, we are currently at 13.8 billion years after the big bang. In other words, 13,800,000,000/100,000,000,000,000, or 0.0138% of the period that we believe that the universe will be habitable.

I understand that isn't an impossibly small percentage, but that seems unusually *soon*. How likely is it that we just so happened to evolve and pop into life at what is essentially the beginning of this period?

Could this indicate that perhaps the universe, or at least the period of habitability in the universe will end much sooner than we believe?

And yes, I know that we can't just make an assumption based on a likelihood- like if something has even the tiniest chance of happening, it probably will happen *somewhere*.

However, humanity has always assumed that we're special in some way, like being the center of the universe, and have been proven wrong time and time again. It seems a lot more likely to me that we'd be closer to an average in the universe than a crazy outlier like being the first 0.01% of life.

Let’s look at the numbers, because they are absolutely staggering.

Every year, the world spends over $2 trillion on militaries, weapons, and bombs. We are spending trillions of dollars perfecting the art of destroying the only home we have ever known.

Meanwhile, global space exploration budgets are a tiny fraction of that. NASA’s annual budget usually hovers around $25 billion—which is roughly what the US military spends in about eleven days.

Imagine what humanity could achieve if we completely flipped the script. If we stopped pouring our wealth into guns and bombs and put everything into space exploration, we wouldn't just be changing our budget—we’d be changing the destiny of our species. Here is why we need to make the switch:

1. The Ultimate ROI (Return on Investment)

Military spending is an economic dead end. A bomb is built, it is dropped, it destroys wealth, and it is gone. Space exploration is the exact opposite. Every dollar spent on space yields massive technological dividends that improve life right here on Earth.

Past dividends: GPS, water purification systems, advanced medical imaging, solar panels, and communications satellites.

Future dividends: Unlimited clean energy from space-based solar power, asteroid mining (which would solve Earth's resource scarcity overnight), and revolutionary materials science.

2. We Need a "Plan B" (and Planet B)

Keeping 100% of humanity on one single rock is a terrible long-term survival strategy. Whether it’s an asteroid impact, a supervolcano, or self-inflicted climate collapse, putting all our eggs in one planetary basket is a massive risk. Funding space exploration isn't about "abandoning Earth"—it's about buying an insurance policy for consciousness itself.

3. War is a Symptom of Scarcity; Space Offers Abundance

Why do humans fight? Historically, it’s almost always over resources, land, and energy.

A single asteroid like 16 Psyche contains enough gold, iron, and nickel to collapse our scarcity-based economies and make resources functionally infinite.

Space offers literally limitless real estate and energy. By moving our heaviest, dirtiest industries off-planet, we could actually heal Earth’s biosphere while continuing to advance technologically.

4. A Unifying Mission for Humanity

War divides us into arbitrary tribes fighting over borders drawn in the dirt. Space exploration does the exact opposite. When you look at Earth from the Moon, you don't see borders; you see a fragile blue marble floating in a void. A massive, global push to explore the cosmos would give humanity a collective, inspiring goal. Instead of young people being sent to fight each other, our brightest minds would be working together to colonize Mars, build starships, and answer the ultimate question: Are we alone?

TL;DR: Weapons of war only buy us temporary security through mutual destruction. Investing in the cosmos buys us a future. It’s time to stop fighting over the crumbs of one world and go claim the cake waiting for us in the universe.

What do you think? If we redirected global military budgets to space for just five years, where do you think we would be?

Our sun may have a few billion years left in its existence. So does planet Earth. And the universe may go on for trillions of years, or ever.

But Earth's habitability for carbon-based life may be curtailed at just over half a billion years.

The sun's luminosity grows about 10% every billion years. This on its own will trigger a run-away greenhouse effect in about a billion years leading to evaporation of our oceans (and the end of most life with it).

But well before this, a more subtle process will be occurring. The increased temperatures from the sun's rising lumonisity will accelerate silicate rock weathering - which leads to increased absorption of CO2 from the atmosphere into the soil and rock.

CO2 will effectively drain from the atmosphere to a point where photosynthesis is no longer possible. With the loss of most plants, oxygen will no longer be refreshed into the atmosphere. And life - at least as we know it - will not be sustained.

Note: There is active scientific debate on how long this process will take - and whether ancillary effects of loss of photosynthesis (such as a lower atmospheric pressure) may lengthen the runway for certain types of plants to continue to exist. But the long-term trend of loss of CO2 in the atmosphere to silicate weathering has been happening over geologic time and will continue to happen.

Mars might be the most off-Earth "hospitable" place for humans in the solar system. And yet it's really really inhospitable.

Mars looks alluringly like parts of the desert southwest of North America, with sunny days and sometimes blue skies. But photos belie the extreme inhospitability of the planet, and the fact that the pressure on Mars is for most intents and purposes smilar to that of outer space.

Lack of atmospheric pressure (it's well less than 1% of Earth's on Mars's surface) is perhaps the most immediate and consequential harsh condition for human life. Exposing our bodies to this pressure (which is essentially like exposing them to the full vacuum of space) would have some immediately terrible consequences, including:

Simultaneous vomiting, defecation, and urination as our pressurized insides push bodily fluids outward.

Boiling away of bodily surface liquids like saliva and eye fluid (water can't exist as a liquid at this pressure, which is a problem for water-based beings).

Extreme swelling of our bodies as dissolved gasses come out of solution and water-based liquids evaporate as internal pressure drops (again no liquid water at this pressure).

Deoxygenation of our blood as oxygen comes out solution, potentially permanently damaging our lungs and in any case leading to unconsciosness within seconds and death within minutes.

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