Could We Terraform Mars?

Summary

This video explores the futuristic and challenging concept of terraforming Mars. It delves into the science behind Mars’ thin atmosphere, the lack of greenhouse gases, and the absence of a magnetic field. The script details potential solutions, from using CO2 from ice caps to large-scale mining operations, solar-powered technology, and even redirecting comets. It also discusses alternative approaches, like building city-sized domes or 'worldhouses,' and touches on broader scientific ideas like magnetic field flipping on Earth. Ultimately, the video imagines a distant future where humanity adapts to and transforms Mars.

Takeaways

• 🚀 Humanity’s future in space is filled with the potential to terraform other planets, starting with Mars.
• 🌍 Mars’ current atmosphere is too thin and cold to support human life, but it was once warmer and had a thicker atmosphere.
• ❄️ One proposed method to terraform Mars is releasing the CO2 from the planet’s polar ice caps, but this wouldn’t be enough to create a sustainable atmosphere.
• 🌋 Mars' lack of a magnetic field, due to its small core, makes it vulnerable to losing any atmosphere it gains to solar winds.
• ⛏️ Extracting CO2 from Mars’ surface or carbonates deep in the crust could increase atmospheric pressure, but would require enormous energy and technology.
• 💡 Terraforming Mars within a generation would require building immense energy infrastructures like solar cells or fusion plants.
• 🌊 Mars has enough water to form some lakes, but not oceans; deep crust sources of water might help.
• 🧪 The new CO2-oxygen atmosphere would still be toxic to humans, requiring photosynthesizing organisms like algae to convert it into something more breathable.
• 🛰️ Long-term solutions could involve introducing nitrogen or redirecting comets to Mars to bring in new atmospheric materials.
• 🏙️ Instead of full-scale terraforming, paraterraforming—covering sections of Mars with domes or ‘worldhouses’—might be a more practical approach for human habitation.

Q & A

What is the main challenge in terraforming Mars?

The main challenge in terraforming Mars is creating a breathable atmosphere with enough pressure, greenhouse effect, and protection from radiation. Mars' current atmosphere is too thin, lacks sufficient CO2 and nitrogen, and does not protect against harmful cosmic rays.

Why is the lack of a magnetic field on Mars significant for its atmosphere?

Mars lacks a global magnetic field, which allowed the solar wind to strip away much of its atmosphere over billions of years. Earth's magnetic field protects its atmosphere by deflecting these solar winds, a protection Mars lacks.

Can nuking Mars' polar ice caps help terraform the planet?

No, nuking Mars' polar ice caps wouldn't release enough CO2 to make a significant difference. The CO2 is buried too deep, and even if all of it were released, it wouldn't be nearly enough to create an atmosphere that resembles Earth's.

What alternative methods are suggested for terraforming Mars?

Alternatives include mining deep carbonates in Mars' crust, introducing 'super' greenhouse gases like CFCs, or crashing comets into the planet to release nitrogen and water. Another idea is to build massive 'worldhouses'—airtight domes covering large areas of the surface.

How much CO2 would be needed to duplicate Earth's atmospheric pressure on Mars?

To duplicate Earth’s atmospheric pressure on Mars, we’d need around 10 tons of CO2 per square meter, which would require digging at least 10 meters deep across the entire planet. This translates to processing quadrillions of tons of rock.

Why can't current technology terraform Mars?

Current technology cannot terraform Mars because the accessible CO2 reserves on the planet are insufficient, and we don't have the energy resources or machinery capable of extracting and processing the necessary materials from Mars' deep crust.

How does the thin Martian atmosphere affect the possibility of liquid water on its surface?

Mars’ thin atmosphere makes liquid water impossible because even if it were warm enough, water would sublimate directly from ice to gas. The thin atmosphere can't retain the heat necessary to sustain liquid water on the surface.

Could photosynthesis help terraform Mars?

Yes, photosynthesis could help terraform Mars, specifically by using certain algae, like cyanobacteria, to oxygenate the atmosphere. These organisms are capable of surviving in a CO2-dominated environment and could begin the process of making Mars' atmosphere more Earth-like.

What role could robotic spacecraft play in Mars' terraforming?

Robotic spacecraft could be used to guide comets from the Kuiper belt to Mars, delivering essential gases like nitrogen and water. A fleet of these spacecraft would nudge comets in the right direction over centuries to contribute to building a breathable atmosphere.

What is a 'worldhouse' and how could it be used on Mars?

A 'worldhouse' is a concept of creating airtight domes or bubbles on Mars that could cover large areas, providing Earth-like environments inside. This approach would be more feasible in the near-term than terraforming the entire planet, as it requires far less energy and material.

Outlines

00:00

🛸 Terraforming Mars: From Science Fiction to Reality

The speaker begins by discussing the science fiction dream of terraforming Mars, referencing popular culture such as Kim Stanley Robinson’s Mars trilogy and Elon Musk's ambitions. They highlight that while humans could settle on Mars in a generation, the planet’s harsh environment—cold, radiation, and lack of atmospheric pressure—necessitates a major transformation. The core challenge lies in creating a breathable atmosphere on Mars, where the planet’s current conditions, with minimal atmospheric pressure and no greenhouse effect, make it uninhabitable. Ultimately, to terraform Mars and make it a second home, humans will need to overcome enormous challenges to sustain life on the planet's surface.

05:01

🌬️ Challenges of Creating a Martian Atmosphere

Terraforming Mars hinges on developing an atmosphere, but current research indicates that it may be impossible in the near future. The hope that Mars' ancient watery surface still contains CO2 and water vapor hidden in its ice caps or crust is met with skepticism. NASA's observations suggest that most of the atmosphere was lost to space due to the planet's weak gravity and lack of a magnetic field. Even if the CO2 locked in the ice caps and regolith were released, it would barely increase the atmospheric pressure, making it inadequate for human survival. The possibility of restoring Mars' atmosphere remains a far-future concept rather than a near-term technological achievement.

10:04

🔬 The Numbers Behind Terraforming: Mining and Energy Requirements

Exploring the detailed requirements for creating a livable atmosphere on Mars, the speaker outlines potential sources of CO2, such as polar ice caps, regolith, and deep carbonates. Even with vast technological advancements, the amount of CO2 available from these sources falls significantly short of what is needed to replicate Earth's atmosphere. The energy required to mine and process CO2 from Mars' surface or extract it from deep carbonates would be immense, demanding technology far beyond our current capabilities. Theoretical approaches like solar cells or fusion power plants could provide the necessary energy, but these solutions are likely centuries away.

15:09

🌊 Water and Oxygen: Terraforming's Key Elements

The hypothetical process of terraforming involves more than just creating a CO2 atmosphere; it also requires oxygen and water. While Mars has enough water for small lakes, the challenge is maintaining oxygen levels, which could be produced by cyanobacteria through photosynthesis. Over time, oxygen would react with the Martian surface, necessitating continuous replenishment. The speaker envisions Mars in the distant future with algae-covered oceans and genetically engineered organisms adapted to a hostile atmosphere. Despite these imaginative solutions, building an Earth-like atmosphere still presents overwhelming obstacles.

🌠 Looking Beyond Mars: The Cometary Bombardment Option

One of the more extreme and far-future ideas for terraforming Mars involves redirecting comets to crash into the planet, introducing nitrogen and other gases to build a more Earth-like atmosphere. This approach would require massive technological developments, with thousands of comets needed to provide enough nitrogen. The speaker paints a picture of robotic spacecraft swarming the outer solar system, nudging comets towards Mars. This bold, sci-fi-like method could ultimately provide the necessary materials for a breathable atmosphere, but it remains a distant possibility.

🛡️ Protecting Mars: Magnetic Fields and Atmosphere Maintenance

After successfully building an atmosphere, Mars would still lack a protective magnetic field. Without this, the new atmosphere would be vulnerable to solar wind and space radiation. While restarting Mars' core to generate a magnetic field is impossible, the speaker suggests an alternative: building a massive external magnetic shield in space. This ambitious project would involve placing an orbiting magnetic field generator between Mars and the Sun. Such a solution is incredibly complex and resource-intensive, but essential for maintaining a sustainable atmosphere.

🏠 Worldhouses: The Pragmatic Alternative to Full Terraforming

Given the extreme challenges of fully terraforming Mars, the speaker introduces an alternative—paraterraforming, or building 'worldhouses.' These would consist of airtight bubbles covering large areas of the Martian surface, creating habitable zones inside. These structures would provide protection from space radiation and micrometeorites while offering a more achievable solution than terraforming the entire planet. While still requiring significant resources, worldhouses represent a more practical step towards making Mars a livable environment for humans.

Keywords

💡Terraforming

Terraforming is the process of transforming a planet’s environment to make it habitable for human life. In the video, the focus is on terraforming Mars by altering its atmosphere to resemble Earth’s. This concept is central to the idea of humanity expanding its reach to other planets, with Mars being the first target for such an endeavor.

💡Mars Atmosphere

Mars’ current atmosphere is 0.6% of Earth's, with little protection from radiation or heat retention, making it inhospitable. The video explores the challenges of thickening this atmosphere through the release of CO2 from the planet’s ice caps or surface, a critical first step in terraforming.

💡Greenhouse Effect

The greenhouse effect refers to how an atmosphere retains heat by trapping sunlight. On Mars, the lack of a sufficient atmosphere leads to minimal greenhouse effect, making the planet too cold for liquid water. The video emphasizes the need to artificially enhance this effect to warm Mars for human habitation.

💡CO2 (Carbon Dioxide)

CO2 is a key greenhouse gas that could help warm Mars if released into the atmosphere. The video discusses various sources of CO2 on Mars, such as polar ice caps and regolith, and the challenges of releasing enough to have an impact on atmospheric pressure and temperature.

💡Magnetic Field

Mars lacks a global magnetic field, which leaves its atmosphere vulnerable to being stripped away by solar wind. In contrast, Earth’s magnetic field protects its atmosphere. The video suggests that any attempt to terraform Mars would need to address this by possibly creating an artificial magnetic shield.

💡Regolith

Regolith refers to the layer of loose, fragmented material covering solid rock, found on the surface of Mars. This material contains small amounts of CO2 that could be released over millennia, but as the video notes, this would provide only a fraction of the atmospheric pressure needed to support human life.

💡Carbonate Minerals

Carbonate minerals, such as calcium carbonate, are chemical compounds that could potentially be mined and processed to release CO2 for Mars’ atmosphere. The video discusses the technical difficulties of extracting these minerals from deep within Mars’ crust and the immense energy required to process them.

💡Comets

Comets, which contain frozen volatiles like CO2, water, and nitrogen, could be redirected to Mars to introduce gases necessary for creating a breathable atmosphere. The video explores this idea, although it acknowledges the difficulty and timescale of capturing and redirecting enough comets to terraform Mars.

💡Cyanobacteria

Cyanobacteria, also known as blue-green algae, were responsible for oxygenating Earth’s atmosphere billions of years ago. In the context of Mars, the video suggests that genetically-engineered cyanobacteria could help produce oxygen as part of the terraforming process, gradually making the atmosphere more hospitable.

💡Worldhouse

A worldhouse is a proposed alternative to full-scale terraforming, where parts of a planet are enclosed under giant domes or bubbles to create a controlled environment. The video presents this as a more feasible near-term solution for colonizing Mars, with massive structures providing breathable air and Earth-like conditions within.

Highlights

Humanity’s future in space includes hopping from one world to the next and terraforming them to create Earth-like environments.

Terraforming Mars would be the first step towards terraforming other worlds, making Mars a second home for humans.

Mars’ current atmospheric pressure is only 0.6% that of Earth, making it uninhabitable without significant modifications.

To terraform Mars, the key is to create an atmosphere, as Mars’ thin atmosphere cannot support liquid water or shield from radiation.

One theory is to release Mars' CO2 reserves by melting the poles to start a greenhouse effect, but the amount of CO2 is insufficient to create a thick atmosphere.

Mars lost its atmosphere over time due to its weak gravitational field and lack of a magnetic shield to protect it from solar winds.

Studies show that Mars' CO2 reserves in its poles and surface are too low to significantly thicken the atmosphere using current or near-future technology.

Processing carbonate minerals on Mars to release CO2 would require strip mining vast quantities of the surface and immense energy.

Even with massive technological advancements, it would take centuries or millennia to create an Earth-like atmosphere on Mars.

Cyanobacteria could help oxygenate Mars’ atmosphere through photosynthesis, though it would take a long time to create a breathable environment.

A far-future solution could involve introducing nitrogen from comets or using robotic spacecraft to alter the composition of Mars' atmosphere.

Building an external magnetic shield in space to protect Mars’ new atmosphere from solar winds could be part of the long-term plan.

An alternative to full terraforming could be constructing massive worldhouses – enclosed ecosystems with breathable air that mimic Earth’s environment.

Terraforming Mars would require immense resources, leading to the question: If we can terraform Mars, why not focus on fixing Earth?

A potential interim solution could be paraterraforming – building enclosed, city-sized bubbles on Mars with Earth-like environments inside.

Transcripts

Thanks to LEGO – presenting LEGO City - for their support of PBS Digital Studios.

Humanity’s future is glorious.

As we master space travel, we’ll hop from one cold dead world to the next. Terraforming as we go.

Life will blossom in our path and eventually the galaxy will shimmer with beautiful Earth-like orbs.

I mean... maybe.

Sounds a little science-fictiony. But it wouldn't sound so far fetched if we proved we could do it at least once.

If we successfully terraformed Mars.

We already have the technology to bring humans to Mars and to set up small settlements

- or at least we could do within a generation.

But those settlements will need to be cocooned - shielded against the deadly cold, the intense radiation

and the fatal lack of atmospheric pressure.

Surely if we want to thrive on Mars – to turn it into our second home – these settlers,

or their descendants, will need to be able open the airlocks, shed their spacesuits,

and step out onto a survivable surface.

We’ll need to terraform Mars, as our first step to terraforming the galaxy.

Terraforming Mars has long been a science fiction dream – from Kim Stanley Robinson’s

Mars trilogy to Total Recall to the Red Faction game series to Elon Musk’s Twitter feed.

But what would it really take?

How science-fiction-y is the whole concept of terraforming?

In the end it’s a question of atmosphere.

Mars’ current atmospheric pressure is 0.6% that of Earth – and that means circulatory shutdown

within a minute for an unprotected humans.

But it also means almost no greenhouse effect.

Light from the Sun, which is already fainter due to Mars’ distance – is radiated directly

back out into space.

On Earth that same light first bounces around in our thick atmosphere, heating it up.

At an average of -60 Celsius, water freezes on Mars.

But even if the planet were warmer, liquid water would still be impossible in that thin

atmosphere – it sublimates directly from ice to gas.

And of course Earth’s atmosphere protects us from harmful cosmic rays and the most dangerous

ultraviolet radiation from the Sun.

All of that bad stuff has a direct path to the Martian surface.

So, the most important step in terraforming Mars is to give it an atmosphere –

ideally as close to Earth’s as possible.

In the imaginations of sci-fi writers all we need to do is unlock the planet’s latent potential.

After all, Mars WAS once a warmer, watery planet with a much thicker atmosphere.

I mean, that's conclusive – our rovers and orbiters have found incontrovertible evidence

of an ancient watery surface.

The hope then, is that this water and the atmosphere that once supported it is now all

locked in the planet’s crust and ice caps.

We just need to release it.

Surely we can just nuke the poles, melt enough carbon dioxide and water vapor to kickstart

a feedback cycle of greenhouse warming and that'll release more gases… and voila!

Earth 2.0

OK, not so fast.

There’s a real risk that Mars actually lost its atmosphere to space, rather than absorbed

it into the surface.

The issue is that the planet is relatively puny.

At 11% the mass of Earth, it has a weaker gravitational field that grips less tightly

to an atmosphere.

And that small size means that the Martian core cooled down more quickly than Earth’s core,

solidifying long ago and shutting down its global magnetic field.

Earth’s magnetic field protects us from the solar wind, as we saw in a recent episode.

The unprotected and loosely bound Martian atmosphere may have been slowly shaved away

by that wind over billions of years.

And in fact that is exactly what happened.

The ablation of what is left of the Martian atmosphere has now been directly observed by NASA’s

MAVEN spacecraft, as we’ve also discussed before.

And the lack of atmospheric material in the crust has been confirmed pretty conclusively

by observations of the Martian surface.

In a nice Nature Astronomy article last year, planetary scientists Bruce Jakosky and Christopher

Edwards calculate the plausibility of using the remaining surface carbon dioxide to replenish

the Martian atmosphere, based on observations of NASA’s Mars Reconnaissance Orbiter and Mars Odyssey spacecraft.

They focus on CO2 because it’s the only plausible greenhouse molecule in any significant

abundance on Mars.

They assess whether release of the accessible CO2 reserves could get Mars anywhere near

Earth’s atmospheric pressure.

And… unfortunately they conclude that no near-future technology could hope to to kickstart

the recovery of any useful atmosphere.

But, you know what?

Let’s go ahead and run the numbers real quick, because maybe something is still possible.

After all, these researchers only ruled out NEAR future technology.

What about medium future?

Far future?

So there are 3 broad sources for CO2 on Mars.

First there’s the south polar icecap – which consists of water ice several kilometers deep,

interspersed with thick layers of CO2 ice – discovered by radar soundings with the

Mars Reconnaissance Orbiter.

If all the polar CO2 were released, it would maybe double the current amount of CO2 in

the atmosphere – which is a factor of around 100 times too low to make a difference.

And by the way, that CO2 couldn’t be released with nukes alone - it’s too deep.

Sorry, Elon.

The second accessible source is CO2 absorbed into the surface dust – the regolith - up to 100m deep.

Unlike, for example, Earth’s permafrost, this stuff wouldn’t just melt under global warming.

It would shift in its equilibrium over 10,000 years to release a small fraction of its CO2.

At any rate, even if we managed to heat the entire regolith across the entire Martian surface

we’d only get 4% of the Earth’s atmospheric pressure.

The final source is carbonate minerals in the crust.

These carbonates would need to be mined and processed by heating to around 300 Celsius.

But complete strip-mining of even the largest carbonate surface deposits on Mars probably get you less carbon

than melting the polar ice caps.

So much for near-future accessible carbon.

But those carbonate minerals probably exist in much larger quantities deep beneath the surface.

And that’s really our only hope to find enough CO2 - or really any native Martian

material - to replenish the atmosphere.

Let’s do a quick calculation to see what it would take.

First, let’s pretend there’s an accessible layer of limestone – calcium carbonate – across

the entire surface of Mars.

There isn’t, but hey, we’re dreamers.

We need about 10,000 kg of material per square meter to duplicate Earth’s atmospheric pressure.

Seriously, that’s how much atmosphere is above your head right now.

No wonder it’s so hard getting out of bed in the morning.

High density limestone is 2500 kg/m^3 and yields 44% of its mass in CO2

when heated or exposed to acid.

So to get 10 tons of CO2 for every square meter on the surface of Mars you’d have to dig down

over 10 meters – across the entire planet!

That’s a few quadrillion tons of rock.

I hope you have your diamond pickaxe ready.

In reality of course we’d need to first locate and then dig down some kilometers before

we could access most of the carbonates.

Extracting such a quantity from depth is hard enough, but let’s think about processing it.

We can either heat the carbonates to hundreds of degrees Celsius or use acid to dissolve

out the CO2.

We’d need to process around 20% of all Martian water via electrolysis to get that acid.

The electrolysis path might be better because it would give us oxygen as a byproduct of making that acid.

The energy cost in both cases is similar, though – several septillion joules.

Several thousand times the total annual energy consumption of the entire Earth.

That’s definitely sounding far-far future.

But not quite impossible.

Finally we actually have a picture of what terraforming Mars would actually look like.

Let’s say we want to finish the work in a single generation.

We’d need to cover much of the surface of Mars in solar cells made from abundant silicon

in the crust, or build 10 or so million gigawatt fusion power plants.

There’s really no other viable energy source.

We’d need to channel this energy deep into the crust to power vast hoards of robotic

miners-slash-processing plants, meanwhile pumping water from the icecaps across the

entire globe.

This could get us a carbon dioxide-oxygen atmosphere in a few decades, or in centuries

… or millenia if you scale down the power supply to something less insane.

Nonetheless, our descendants could see a Mars with sufficient air pressure and greenhouse

effect to allow liquid water to persist on the surface.

Now, Mars actually does have enough water for a few lakes and rivers.

The ice cap water would cover the entire surface to about 30 meters – which is not enough

to start a proper water cycle or have oceans,

but there may be a lot more water deeper in the crust.

We’d better hope so.

Our brand new CO2-oxygen atmosphere is not exactly earth-like.

In fact, it’s instantly and fatally toxic to humans and animals,

and not so great for plant life.

Certain algaes can survive in a pure CO2 atmosphere –which is handy, because blue-green algae

– cyanobacteria - was responsible for first oxygenating Earth’s atmosphere.

And we’ll need that photosynthesis because otherwise oxygen will be quickly leeched from

the atmosphere as it oxidizes the surface.

So, there’s our next snapshot of the far future of a terraformed Mars –

brand new oceans green with photosynthesizing, probably genetically-engineered, slime.

And perhaps eventually a breed of post-humans genetically or even cybernetically adapted

to deal with a CO2 atmosphere.

I just described the “easy” path to building an atmosphere on Mars.

It may be the only way to do it only using Martian materials.

Variations are possible - like introducing “super” greenhouse gases like CFCs.

But that still doesn’t give us the needed atmospheric pressure.

At any rate, to get a true Earth-like atmosphere we need a non-toxic filler molecule.

CO2 sucks.

Nitrogen is much better - it works great on Earth anyway, but Mars has very little of the stuff.

To really build an Earth-like atmosphere we have to turn our eyes to the rest of the solar system.

One popular idea is just to smack some comets into Mars.

Comets contain tons of frozen volatiles – gas-forming molecules like CO2, H20 and the presence of

molecular nitrogen in comets was only recently confirmed by the Rosetta mission.

But how many comets do we need?

Well, assuming comets contain an amount of nitrogen similar to the composition of the

pre-solar nebula then can guess that around 5% of a comet’s mass is nitrogen.

That gives the typical medium-to-large comet a hundred billion tons of the stuff.

So, to build a quadrillion-ton nitrogen atmosphere that’s, like, 10,000 comets.

O-kay, so we’re still in far-future la-la land.

But it’s actually not significantly less crazy, or more crazy, than melting the Martian surface.

What would THIS effort look like?

Imagine this - a vast fleet of robotic spacecraft swarming the Kuiper belt, nudging its plentiful

iceballs in just the right way to send them plowing towards Mars.

Hopefully with exquisite aim, otherwise Earth is in for a pounding, also.

It would presumably take centuries to put such a fleet in place, and more centuries

to “de-orbit” those comets.

Once Mars has been suitably bombarded there’s still a lot of work tweaking the new atmosphere.

The good news is that those comets brought with them a LOT of water,

so we have deep global oceans at this point.

OK.

Let’s fast-forward several centuries.

Mars has an atmosphere – either released from deep in the crust or brought in from

the far outer solar system.

The last step is to protect the new atmosphere.

We canNOT restart Mars’ magnetic field – to do that we’d have to re-melt the entire

core.

But we can try to build an external magnetic shield.

The easiest would be to do that in space – an orbiting field generator placed between Mars

and the Sun, like a giant space umbrella.

The resources and energy needed to build this is insane – but hey, we just built an atmosphere,

so why not?

Honestly, all of this is pretty insane.

And frankly, unlikely.

Would we really muster the resources to terraform Mars if we can’t do the same to re-terraform

Earth?

But there is another option.

Why build a sky if we can build a roof?

Instead of terraforming – what if we paraterraform.

Build what is known as a worldhouse.

We could cover vast tracts of land with an airtight bubble.

Or, more likely, many many connected bubbles.

These would be tall enough to encapsulate entire cities, and importantly –

plenty of Earth-like natural wilderness.

Oh, and I’m still a proponent of centrifuge cities – mag-lev rotating habitats to simulate

Earth gravity. Also shown rather beautifully in this more practical design by James Telfer.

If we wanted to cover, say, 10% of the Martian surface with a 300 meter tall worldhouse,

it'd require several orders of magnitude less material than building an entire atmosphere.

So, say a handful of comets and/or the polar ice caps

should be enough to fill our worldhouse with air and water.

Now, without a real atmosphere, space radiation is gonna be a problem for our worldhouse,

as is the constant bombardment of micro-meteors.

People who live in glass houses shouldn’t throw stones, nor live under a stone-throwing universe.

But perhaps there are advanced or just very, very thick materials that would serve.

So there’s our final image of humanity’s future on Mars: thousands of city-sized bubbles

spread across the still-barren landscape.

And inside each bubble an oasis – a lush, snow-globe replica of old Earth.

However we do it, Mars will surely be our first step, our proof of concept if we choose

that destiny - if we choose to terraform space time.

Thanks to LEGO – presenting LEGO City - for their support of PBS Digital Studios.

Can you believe it’s been 50 years since we landed on the moon?

It started out with one small step for man and now the journey to Mars is right around the corner!

Featuring sets inspired by real aerospace technology, LEGO City Space aims to inspire

future space explorers to imagine what role they can play to get us to the Red Planet.

To discover more go to the link in the description.

So we missed a couple of comment responses.

Today I'm going to cover two episodes: The episode "What Happened Before the Big Bang",

in which we look at eternal inflation. As well as the episode on the exciting possibility

that the North and South magnetic poles may be about to flip.

Wabi Sabi asks why the inflaton field is assumed to be a scalar field.

Well, that's a great question - but I'm afraid the answer may not be satisfying.

It's because a scalar field is all you need.

This is the simplest type of quantum field, consisting of only a single scalar value at all points in space.

Give such a field a constant energy density and you get exponential expansion.

But more complex fields like vector fields and spinor fields can do the job too -

and some inflationary models use them, resulting in more complex inflation scenarios.

But many physicists argue that you shouldn't add unnecessary complexity, so a scalar field

tends to be the default for inflaton.

Joshua Kahky asks whether the Inflaton Field could also explain Dark Energy.

Well, the answer is yes, possibly.

Inflation supposedly happened because the inflaton field had a very high energy density,

and it stopped when that energy dropped to a very low value.

But that low value may not have been zero.

If the inflaton field was left with a very tiny but positive energy density,

then it's possible that it could now be powering the current accelerating expansion that we call dark energy.

But for that to happen, the inflaton field would have had to have transitioned between

two stable or semi-stable states that are a factor of 10^27 different in energy.

Now, we can try to imagine a single field with that property, or we can imagine two separate fields -

It's not clear which of those two imaginings is more of a stretch.

There were a lot more great questions on eternal inflation, but I'll get to those when we do

the eternal inflation challenge question answer episode.

For now, let's move on to the possible flipping of Earth's North and South magnetic poles.

EarthKnight points out that while Venus lacks an Earth-type intrinsic magnetic field,

the solar wind striking its atmosphere creates an induced magnetic field that does protects the planet.

That's a nice point, EarthKnight.

It's a very cool effect.

The solar wind partially ionizes Venus's upper atmosphere.

Electrical currents are induced and these produce a magnetic field that pushes back

against the Sun's magnetic field.

Venus's magnetic force-shield isn't nearly as strong as Earth's, however, so our Venusian

floating cloud cities had better still have very thick roofs.

As many viewers noted, what we currently call the north magnetic pole is technically a south

magnetic pole - as in, what we would call the south pole of a magnetic dipole or a bar magnet.

You know how the magnetic north pole of a bar magnet is attracted to the south pole of a second bar magnet?

Well, your compass's north pole is attracted to geographic north - which means geographic

north must correspond to a magnetic south pole.

Nolan Westrich, while laughing in Australian, notes that with the flipping of the magnetic

poles it will be America's turn to be upside down.

Well, given that the northern hemisphere is currently the magnetic south, I think that

means that North America, Europe, and most of Asia have been at bottom of the world all

this time without realizing it.

So hold onto something and don't look at the sky - it's a long way down.