Neil deGrasse Tyson: 3 mind-blowing space facts | Big Think

Summary

Neil deGrasse Tyson explores the possibilities of life beyond Earth's habitable zone. He explains how tidal forces from Jupiter's gravity warm its moon Europa, allowing liquid water to exist beneath its icy surface. This broadens the search for extraterrestrial life beyond the traditional 'Goldilocks Zone.' He also discusses dark matter, clarifying that it should be called 'dark gravity' since its nature is unknown. Tyson suggests it may be a family of particles that don't interact with ordinary matter except gravitationally. He humorously ties Earth's rotation to a dramatic football field goal, illustrating the Coriolis force that drives storms.

Takeaways

• 🌍 The habitable 'Goldilocks Zone' around a star is the region where liquid water can exist, which is crucial for life as we know it.
• 🌋 Jupiter's moon Europa, although outside the habitable zone, has an internal ocean kept warm by tidal forces from Jupiter, making it a potential host for life.
• 🌊 Tidal forces from Jupiter cause flexing and distortion of Europa's surface, generating heat through friction, similar to warming up a racquetball.
• 🥶 Europa's frozen surface shows cracks and ridges, indicating an underlying liquid ocean beneath the ice.
• 🔬 The discovery of potential liquid water environments beyond the habitable zone broadens the search for life in the universe.
• 🌘 Some of Jupiter's moons, like Io, are so affected by tidal forces that they have active volcanoes on their surfaces.
• 🔭 The measurement of gravity in the universe shows that 85% of it has an unknown origin, referred to as 'dark matter' or more accurately, 'dark gravity.'
• 🌌 Dark matter/gravity does not interact with ordinary matter or even itself, existing as a diffuse, spread-out mass throughout the universe.
• ⚛️ Dark matter is likely composed of a new class of subatomic particles that hardly interact with known particles, similar to neutrinos.
• 🌎 The Earth's rotation (Coriolis force) can affect the trajectory of objects like footballs, and is responsible for the circulation of storms like hurricanes and cyclones.

Q & A

What is the Goldilocks Zone or habitable zone?

The Goldilocks Zone or habitable zone is the region around a star where liquid water can potentially exist on a planet's surface, making it suitable for life as we know it.

How is Europa, a moon of Jupiter, kept warm despite being outside the habitable zone?

Europa is kept warm not by the Sun, but by tidal forces from Jupiter itself. As Europa orbits Jupiter, its shape changes due to Jupiter's gravitational pull, generating internal friction and heat.

What evidence suggests that Europa has an ocean of liquid water beneath its icy surface?

The surface of Europa shows cracks, ridges, and shifted ice chunks, indicating that the interior cannot be completely frozen. These features resemble the shifting ice sheets seen in Earth's Arctic Ocean.

Why is the search for life in the universe no longer limited to the Goldilocks Zone?

The discovery that tidal forces can provide heat and potential liquid water on moons like Europa means that the search for life can extend beyond the habitable zones around stars.

What is the problem with the term 'dark matter'?

The term 'dark matter' implies that we know it is matter, but in reality, we don't know what it is. A more accurate term would be 'dark gravity' since we only know that it has gravitational effects.

How is dark matter detected and measured?

Dark matter is detected by observing the rotational speed of galaxies, which is faster than expected based on the visible matter alone. This excess gravitational force is attributed to the presence of unseen 'dark matter'.

What is the current leading theory about the nature of dark matter?

The leading theory is that dark matter consists of a family of subatomic particles that hardly interact with ordinary matter, except through gravitational forces.

How does dark matter differ from ordinary matter in terms of self-interaction?

Dark matter not only doesn't interact with ordinary matter, but it also doesn't interact with itself, which is why it is spread out diffusely rather than concentrated in specific locations.

What is the Coriolis force, and how did it affect the winning field goal kick in the football game example?

The Coriolis force is the deflection caused by the Earth's rotation. In the football game example, the Coriolis force caused a third of an inch drift to the right, enabling the winning field goal kick.

What is the significance of the Coriolis force beyond its impact on a football game?

The Coriolis force is responsible for creating the circulation patterns of storms like hurricanes, tornadoes, and cyclones in the Pacific.

Outlines

00:00

🌍 Conditions for Life Outside the Goldilocks Zone

Neil deGrasse Tyson explains how liquid water, essential for life as we know it, can exist outside the habitable zone around a star due to tidal forces from a large nearby body like Jupiter. He uses the example of Europa, a moon of Jupiter, where the tidal forces from Jupiter's gravity heat the interior, creating a subsurface ocean of liquid water beneath the icy crust. This broadens the search for potential life in the universe beyond just the Goldilocks zones of stars.

05:02

🔭 Exploring the Nature of Dark Matter

Tyson discusses the concept of dark matter, which accounts for 85% of the gravity in the universe but has no known origin. He suggests that a more accurate term would be 'dark gravity' since we don't know if it's actually matter. He explains how the presence of dark matter is measured by observing the rotation rates of galaxies, which indicate more gravitational force than can be accounted for by visible matter alone. Tyson speculates that dark matter may be a family of subatomic particles that don't interact with ordinary matter except through gravity.

10:03

🌀 The Coriolis Effect and its Influence

Tyson shares an anecdote about watching a football game where a field goal was slightly deflected due to the Earth's rotation, known as the Coriolis effect. He explains that this effect, caused by the Earth's rotation, is responsible for the circulation patterns of storms like hurricanes and cyclones. Tyson used this event as an opportunity to educate people about the Coriolis force and its impact on various phenomena.

Keywords

💡Goldilocks Zone

The Goldilocks Zone, also known as the habitable zone, is a region around a star where the temperature conditions would allow liquid water to exist on the surface of a planet or moon. This concept is mentioned as a place where we typically look for life, as liquid water is considered essential for life as we know it. The script explains that if a planet is too close to the star, the heat would evaporate water, and if it's too far away, the water would freeze, making both states unsuitable for life.

💡Tidal Forces

Tidal forces refer to the gravitational forces exerted by a larger celestial body on a smaller body, causing the smaller body to experience periodic deformations or bulges. The script discusses how tidal forces from Jupiter cause heating and energy transfer within its moon Europa, despite being outside the Goldilocks Zone. These tidal forces distort Europa's shape as it orbits Jupiter, pumping energy into the moon and potentially sustaining liquid water beneath its icy surface, creating conditions hospitable for life.

💡Liquid Water

Liquid water is emphasized as a crucial ingredient for life as we know it. The script repeatedly mentions the significance of finding liquid water on planets or moons, as it is considered a prime indicator of potential habitable conditions. The presence of liquid water on Europa, facilitated by tidal heating, is presented as a promising opportunity to search for extraterrestrial life, even outside the Goldilocks Zone.

💡Dark Matter

Dark matter is a hypothetical form of matter that cannot be directly observed but whose existence is inferred from its gravitational effects on visible matter and galaxies. The script discusses how 85% of the gravity in the universe has an unknown origin, attributed to dark matter. It also suggests that the term "dark gravity" might be more accurate, as we don't know the nature of this unseen force. Understanding dark matter is presented as a significant challenge in our understanding of the universe.

💡Gravitational Interactions

Gravitational interactions refer to the attractive force that exists between objects with mass. The script discusses how we can measure the collective gravity of various celestial bodies, such as stars, planets, and galaxies, and how a significant portion of this gravity has an unknown origin, leading to the concept of dark matter. It also highlights how gravitational interactions within a galaxy can be used to infer the presence of unseen matter, or dark matter, based on the observed rotation rates.

💡Subatomic Particles

Subatomic particles are the fundamental constituents of matter that make up atoms. The script suggests that dark matter might be a family of subatomic particles that have very weak interactions with ordinary matter. It draws an analogy with neutrinos, which are known subatomic particles that barely interact with regular matter, to illustrate the possibility of an entirely new category of particles responsible for dark matter.

💡Coriolis Force

The Coriolis force is an apparent force that arises due to the rotation of the Earth. It causes objects in motion to appear to deflect from their intended path, with the direction of deflection depending on the hemisphere and the direction of motion. The script provides an example of a winning field goal in a football game, where the rotation of the Earth likely caused a slight drift in the ball's trajectory, enabling the successful kick. The Coriolis force is also mentioned as the driving force behind the circulation of storms like hurricanes and cyclones.

💡Planetary Motion

Planetary motion refers to the movement of celestial bodies, such as planets and moons, within a larger system like the Solar System. The script discusses the orbital motion of Europa around Jupiter and how this motion, combined with tidal forces, causes distortions and energy transfer within Europa. Understanding planetary motion and the associated gravitational interactions is crucial in predicting and explaining phenomena like tidal heating and potential habitability.

💡Scientific Observation

Scientific observation involves the careful and systematic study of natural phenomena through various means, such as visual inspection, measurement, and data collection. The script emphasizes the importance of observing and analyzing the surface features of Europa, like cracks and ridges in the ice, to deduce that the moon cannot be completely frozen and likely harbors an ocean beneath its surface. Scientific observation forms the basis for advancing our understanding of celestial bodies and the processes governing their behavior.

💡Extraterrestrial Life

Extraterrestrial life refers to the potential existence of life forms beyond Earth, on other planets, moons, or celestial bodies. The script discusses how the discovery of conditions suitable for liquid water, even outside the Goldilocks Zone, has broadened the search for extraterrestrial life in the universe. The possibility of life thriving on Europa, despite its distant location from the Sun, is presented as a promising avenue for exploring the potential for extraterrestrial life in our Solar System and beyond.

Highlights

The habitable zone, or 'Goldilocks Zone,' around a star is the region where liquid water can exist on a planet's surface, which is considered a key requirement for life as we know it.

Europa, a moon of Jupiter, is kept warm not by the Sun but by tidal forces from Jupiter, which pump energy into Europa and prevent its surface water from completely freezing.

The evidence that Europa has an ocean of liquid water underneath its icy surface comes from observations of cracks, ridges, and shifts in the surface ice, indicating internal movements.

Finding liquid water on Europa, outside of the Sun's habitable zone, broadens the search for life in the universe beyond planets orbiting in the Goldilocks Zone.

Io, another moon of Jupiter, is so hot from tidal forces that it has active volcanoes, demonstrating that sources of energy for potential life do not need to be limited to a host star.

Dark matter is a phenomenon where 85% of the gravity in the universe has no known origin when measured against the collective gravity of observable matter.

A more accurate term for 'dark matter' would be 'dark gravity,' as it does not presume any knowledge about the nature of the unseen source of gravity.

The leading hypothesis for dark matter is that it consists of a family of subatomic particles that interact very weakly or not at all with ordinary matter.

Dark matter not only does not interact with ordinary matter, but it also does not interact with itself, which prevents it from accumulating into concentrated objects like planets or galaxies.

A calculation showed that the Earth's rotation likely caused a winning field goal kick in an overtime football game to drift slightly, demonstrating the Coriolis effect.

The Coriolis effect, caused by the Earth's rotation, is responsible for the circulation patterns of storms such as hurricanes, tornadoes, and cyclones.

Even small fractions of an inch can matter significantly in sports involving spherical objects and cylindrical targets, due to the complex physics involved.

Neutrinos, ghostly particles that hardly interact with ordinary matter, serve as an example within the Standard Model of particles that can be elusive and weakly interacting.

Dark matter is measured by comparing the observed orbital velocities of galaxies to the gravitational pull calculated from the visible matter, revealing a large discrepancy.

The tidal forces that heat Europa and Io are analogous to the process of warming up a racquetball by distorting it and allowing its resilience to pump energy into the ball.

Transcripts

NEIL DEGRASSE TYSON: When we think of places you might find life we typically think of

the Goldilocks Zone around the star where water would be liquid in its natural state.

And if you get a little too close to the star, heat would evaporate the water and you don't

have it anymore.

It's gone.

Too far away it would freeze and neither of those states of H2O are useful to life as

we know it.

We need liquid water.

So you can establish this Green Zone, this habitable zone, this Goldilocks Zone, where

if you find a planet orbiting there hey, good chance it could have liquid water.

Let's look there first for life as we know it.

Now it turns out that this source of heat, of course is traceable to the sun and if you

go farther out everything water should be frozen, all other things being equal.

But Europa, a moon of Jupiter sitting well outside of the Goldilocks Zone is kept warm

not from energy sources traceable to the Sun, but from what we call the tidal forces of

Jupiter itself.

So, Jupiter and surrounding moons are actually pumping energy into Europa.

And how does it do that?

As Europa orbits Jupiter its shape changes.

It's not fundamentally different from tides rising and falling on Earth.

The shape of the water system of the Earth is responding to tidal forces of the moon.

And when you do that to a solid object, the solid object is stressing.

And because of this, a consequence of this is that you are pumping energy into the object.

It is no different from when you say to anyone who's familiar with racquet sports, indoor

racquet sports.

It could be racquetball or squash.

You say let's arm up the ball before we start playing.

You want to hit it around a few times.

You are literally warming up the ball.

It's not just simply let's get loose.

You are literally warming up the ball.

How?

You are distorting it every time you smack it and then the resilience of the ball pops

it back into shape and every time you do that, every smack, you're pumping energy into the

ball.

It's not fundamentally different from what's going on in orbit around Jupiter.

So, you have this frozen world, Europa, completely frozen on its surface but you look at the

surface and there are cracks in the ice.

There are ridges in the ice where there's a crack and it shifted and then refroze.

So this ridge has a discontinuity in the crack and it continues in another place.

So what this tells you is that Europe cannot be completely frozen because if it were nothing

would be moving.

You look at the surface of Europa, the frozen surface, there are like ice chunks that are

shifted and refrozen and shifted again.

It looks just like if you fly over the Arctic Ocean.

Fly over the Arctic Ocean in the winter these are ice sheets that are breaking and refreezing

all the time.

It's the same signature as that.

So all of us are convinced that beneath this icy surface is an ocean of liquid water.

And there's no reason to think it wouldn't have been liquid for billions of years.

On Earth where we find liquid water we find life.

So what this means not only do we have a source of heat outside of the Goldilocks Zone, we

have conditions under which life could be thriving.

And knowing that this is possible has completely broadened the net that we are casting in search

for life in the universe.

No longer is it the limit, let's find a 72 degree tidal pond and see life forming there.

No, life is pretty hardy.

And by the way Europa is not the only one of these moons in the outer solar system that's

kept warm by these sort of tidal stress forces.

There are other moons that feel the same influx of energy.

So, for example, Io, that's the innermost moon of Jupiter.

That suffers from this phenomenon even more.

And that moon is so hot there are volcanoes erupting from within.

It is rendered molten, whatever solid parts of that moon there are.

And so, in fact, the most volcanically active place in the solar system is Io, one of the

moons of Jupiter.

And we don't know how to sustain life under temperatures that hot so, but it's a reminder

that if you're looking for sources of energy we no longer need to be anchored to a host

star in our search for life in the universe.

The question isn't about whether dark matter exists or not.

What's going on is when we measure gravity in the universe the collective gravity of

the stars, the planets, the moons, the gas clouds, the black holes, the whole galaxies.

When we do this 85 percent has no known origin.

So it's not a matter of whether dark matter exists or not.

It's a measurement, period.

Now, dark matter is not even what we should be calling it because that implies that it's

matter.

It implies we know something about it that we actually don't.

So a more precise labeling for it would be dark gravity.

Now, if I called it dark gravity are you going to say does dark gravity really exist?

I'd say yeah because 85 percent of the gravity has no known origin.

There it is.

Let's figure out what's causing it.

The fact that the word matter got into that word is forcing people to say I have another

idea.

I bet it's not matter.

It could be something else.

We're overreacting to a label that overstates our actual insights or knowledge into what

it is we're describing.

Then I just joke we should just call it Fred.

Fred or Wilma, something where there is no reference to what we think it is because,

in fact, we have no idea.

So here's how you actually measure the stuff.

In a galaxy which is the smallest aggregation of matter where dark matter manifests, so

you look how fast it's rotating and we know from laws of gravity first laid down by Johannes

Kepler and then enhanced and given further detail and deeper understanding by Isaac Newton.

You write down these equations and say oh, look how fast it's rotating.

You invoke that rotation rate in the equation and out the other side says how much gravity.

How much mass should be there attracting you.

And the more mass that's there the faster we expect you to be orbiting.

That kind of makes sense.

So when you do this calculation on a galactic scale we get vastly more mass attracting you

than we actually can detect.

I'm adding up stars, gas clouds, moons, planets, black holes.

Add it all up.

It's a fraction of what we know is attracting you in this orbit.

And we cannot detect the rest.

And so we hand it this title dark matter.

Understandably I suppose but it implies that we know that it's matter, but we don't.

We know we can't detect it in any known way and we know it has gravity.

So it really should be called dark gravity.

I think the over/under on what dark matter might be today I think we're all kind of leaning

towards a family of particles, subatomic particles that have hardly any ability to interact with

the particles we have come to know and love, ""ordinary matter.""

And that would make it matter.

Dark matter as we've all been describing it.

And it's not a weird thing that you could have a particle that doesn't interact with

our particles.

Within our own family of particles there are examples where the interaction is very weak

or nonexistent.

You might have heard of neutrinos.

This is a ghost-like particle that permeates the universe and hardly interacts with familiar

matter at all.

Yet it is part of our family of particles that we know exist and that we can detect

and interact with.

So if we can have an illusive particle that's part of our own familiar family of particles

it's not much of a stretch to think of a whole other category of particles where none of

them give a rat's ass about the rest of us and they just pass right through us as though

we're not even there.

Now here's what's interesting about dark matter.

We know it doesn't interact with us except gravitationally.

By the way what do I mean by interact?

Does it bind and make atoms and molecules and solid objects?

No, it does not interact with us in any important known way.

But it also doesn't interact with itself.

That's what's interesting.

So, if it interacted with itself you can imagine finding dark matter planets, dark matter galaxies

because to interact with yourself is what allows you to accumulate and have a concentration

of matter in one place versus another.

These are the atomic bonds and the molecular bonds that create solid objects and if particles

do not interact with one another they just pass through, you just have this zone of mass

not really doing anything interesting.

So, dark matter not only doesn't interact with us, it doesn't interact with itself.

And that's why when we find dark matter across the universe it's very diffusely spread out.

It's like over here.

It's not in this one spot and look at this concentration.

No, that's not how that works.

Just as a quick example, I was channel surfing, came across a football game that had just

ended in a tie.

They went into overtime.

I had 15 minutes to kill before my movie came on.

I said I'll sit there and watch this overtime period.

And I'm watching it and there's the requisite exchange of possession before you go into

sudden death overtime.

So, they get it to within 50 yards of the goalpost and so they decide to kick a field

goal for the win.

And so I'm watching this and it's exciting, right.

So then the ball gets hiked, they kick, the ball tumbles and it heads toward the left

upright, careens off the left post and in for the win.

And I said wait a minute.

Oh, we have a round ball and a cylindrical thing so fractions of an inch matter which

way this will bounce off of a post.

So I said let me check this out.

So I check the orientation of the stadium, the latitude of the city and I did a calculation

and then I tweeted and I said, ""The winning field goal by the Cincinnati Bengals in overtime

was likely enabled by a third of an inch drift to the right, enabled by Earth's rotation.""

And people say oh, my god.

Blow my mind.

And the local news got it and everybody got it.

Of course you want to know that the rotation of the Earth helped that field goal kick.

Because a kick going due north or due south will be deflected to the right in the northern

hemisphere.

And that's exactly what happened to that kick.

And I use that as an excuse to send out a second tweet saying, ""By the way, we call

this the Coriolis force and that's what creates the circulation of all storms.

Hurricanes, tornadoes.""

What do they call them in the Pacific?

Cyclones.