Category: earth

For The Last Time: The LHC Will Not Make An Ea…

For The Last Time: The LHC Will Not Make An Earth-Swallowing Black Hole

“To prevent decay, new, unknown physics — for which no evidence exists — must be invoked.

Even if the newly created black hole were stable, it could not devour the Earth. The maximum rate it could consume matter is 1.1 × 10-25 grams-per-second.

It would take 3 trillion years to grow to a mass of 1 kg.”

Well, it was only a matter of time before someone trotted out the long-debunked claim that the LHC could possibly create an Earth-destroying black hole. I, like most of you, just didn’t expect that person to be the esteemed astronomer Sir Martin Rees!

Well, you’ll be happy to know that not only is his claim untrue, but it’s very easy to demonstrate why. You don’t have to point to cosmic rays (which are more energetic and have struck Earth for billions of years) or rely on anything we haven’t already directly observed. In fact, we can even imagine exotic scenarios that could result in the creation of a black hole, and even then, the Earth is entirely safe.

In less than 200 words, you, too, can learn why the LHC will not make an Earth-swallowing black hole. Sorry, all you armchair supervillains out there.

Pieces Of Mars Have Landed On Earth

Pieces Of Mars Have Landed On Earth

“All three of these types are notably different from all the other meteorites found on Earth, but have elemental and isotopic commonalities with one another. The ratio of their oxygen isotopes, in particular, were different from that of other meteorites, as well as having younger formation ages. For a long time, scientists suspected they might have a common origin to one another, distinct from the more typical meteorites.

In 1976, the Viking landers returned direct information about the Martian surface, including the Martian atmosphere and the rocks found on the ground. The similarities were striking, leading many to hypothesize that all three types originated from Mars. But the true “smoking gun” came in 1983, when a variety of trapped gases were found in glass formed by the impact of one such shergottite, and it matched the gases found by Viking on Mars.”

Many of us have witnessed meteor showers, bolides, or even randomly large bodies strike the atmosphere of Earth and leave a brilliant streak across the sky. Every once in a while, such a strike will result in an impact on Earth’s surface, leaving a meteorite behind. As of today, over 61,000 meteorites have been discovered, with most of them having huge commonalities of their physical and chemical properties. A few of them, however, are weirdos. They’re younger, they haven’t been in space for very long, and they’re made out of a different mix of materials from the others. For years, it was speculated that they came from Mars, and with the advent of robotic exploration of the surface, we’ve finally found the smoking gun evidence.

About 0.3% of all the meteorites on Earth have a Martian origin. There are pieces of Mars landing on Earth, and the Solar System is richer for it.

Our Sun Is Lighter Than Ever, And The Problem …

Our Sun Is Lighter Than Ever, And The Problem Is Getting Worse

“As time goes on, the amount of mass lost by the Sun will increase, particularly as it enters the giant phase of its life. But even at this relatively steady rate, the growth of helium in the Sun’s core means that we will heat up here on planet Earth. After about 1-to-2 billion years, the Sun will be burning hot enough that Earth’s oceans will boil away entirely, making liquid water impossible on the surface of our planet. As the Sun gets lighter and lighter, it will counterintuitively get hotter and hotter. Our planet has already used up approximately three-quarters of the time we have where Earth is habitable. As the Sun continues to lose mass, humanity and all life on Earth approaches its inevitable fate. Let’s make these last billion-or-so years count.”

As the Sun burns through its nuclear fuel, it loses mass in not one, but two ways. Sure, in its core, it’s fusing hydrogen in a chain reaction into helium, with the reduction in mass corresponding to a gain in energy: the energy that powers the Sun and gives life to all the planets. But it also blows off particles, including electrons, protons, and atomic nuclei, in a phenomenon called the solar wind. Even though more massive stars burn hotter and brighter than less massive ones, the Sun, perhaps paradoxically, will increase in temperature and luminosity as it loses mass to these two processes. The Sun is getting lighter and lighter, and the problem of its increasing energy output will eventually destroy all life on Earth.

Here’s how fast the Sun is losing mass, and what this means for the inevitable fate of everything that could ever live here on Earth.

Ask Ethan: How Do We Know The Age Of The Solar…

Ask Ethan: How Do We Know The Age Of The Solar System?

“How do we know the age of our solar system? […] I have a loose grasp on the concept of dating the time elapsed since a rock was liquid, but 4.5 Billion years is roughly how long ago Theia hit proto-Earth liquefying a massive amount of everything. […] How do we know we’re actually dating the solar system and not just finding dozens of ways to date the Theia collision?”

You’ve probably heard the estimates before: that the Earth, the Sun, and the rest of the Solar System are all about 4.5 or 4.6 billion years old. But why be so imprecise? We don’t have to be! In fact, we know that there are slight variations, and based on the fact that we think that the Earth-Moon system formed from a giant impact tens of millions of years after the rest of the Solar System did, we shouldn’t get the same answer for everything! It turns out that we’ve now advanced to the point where we can actually give answers that are extremely accurate: the Earth-Moon system should be 4.51 billion years old; the oldest meteorites show an age for the rest of the Solar System of 4.568 billion years, and the Sun may be a little older at 4.6 billion years.

How do we know? The science of radioactive decay holds the answer, and it’s a lot more complex, but a lot more well-understood, than you might think!

Remnants Of Our Solar System’s Formation Found…

Remnants Of Our Solar System’s Formation Found In Our Interplanetary Dust

“Our naive picture of a disk that gets very hot, fragments, and cools to then form planets may be hopelessly oversimplified. Instead, we’ve learned that it may actually be cold, outer material that holds the key to our planetary backyard. If the conclusions of the Ishii et al. paper stand the test of time, we may have just revolutionized our understanding of how all planetary systems come into being.”

How did Earth (and the other planets) form? According to conventional wisdom, a molecular cloud collapsed, formed a protoplanetary disk, funneled material into the center, and gave birth to a star. This star then blew off the gas and light elements from the inner Solar System, with the planets we have today representing the survivors from these hot, early stages. Only, what if that picture weren’t correct after all? What if the material that gave rise to our (and other) worlds wasn’t forged in an inferno, but in a colder, more distant environment that only fell into the inner reaches at a later time?

The way to decide would be to identify and examine material left over from these early stages of Solar System formation in enough detail. For the first time, we’ve done exactly that. Don’t miss the results!

Could We Create A Bottomless Pit On Earth?

Could We Create A Bottomless Pit On Earth?

“A round-trip journey, from the North Pole to just shy of the South Pole and back to the North Pole again, all through the Earth’s center, should take just a whisker under 90 minutes. Under ideal conditions:

* creating a vacuum,
* straight through the Earth’s rotational axis,
* starting with no tangential velocity,
* devoid of any type of air resistance and subject only to gravitational forces,

you’d wind up right back where you started just 90 minutes later: roughly the same time it takes the international space station to orbit the Earth. So long as you brought an oxygen supply with you, you’d be no worse for the wear.”

From tourist traps to Alice in Wonderland to modern entertainment like Gravity Falls, bottomless pits are tropes that hardly seem physically possible. Sure, you can always envision a thought experiment, but that doesn’t mean you could actually build one. Despite the engineering challenges and the enormous expense that would be associated with such a project, this one turns out to be physically plausible with not-too-distant-future technology. There are a number of obstacles we’d have to overcome, including the Earth’s rotation, drilling a shaft clear through the planet, and stabilizing a passenger against the heat and radioactivity of the natural interior of our world. But if we could do it, and not get stuck at the center, we’d come back to where we started just 90 minutes later.

Here’s the story behind how to create and successfully use a bottomless pit here on Earth!

Earth’s rotation is slowing slightly with time

Earth’s rotation is slowing slightly with time:

“In the year 1820, a rotation took exactly 24 hours, or 86,400
standard seconds. Since 1820, the mean solar day has increased by about
2.5 milliseconds.”

“At the time of the dinosaurs, Earth completed one rotation in
about 23 hours,” says MacMillan, who is a member of the VLBI team at
NASA Goddard.

* How can the moon slow down the earth ?

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Are the heavens moving or are we?

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In the previous series of posts, we discussed about the key role that a rotating earth plays in space shuttle launches and quickly skimmed through why the earth began to rotate in the first place.

But in the 21st century, there are many experiments  (Coriolis effect,  Foucault’s pendulum ,etc, etc) that you can do to convince yourself that the Earth is indeed rotating.

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                                             ISS Live Stream

But back in the days of Galileo it was still debatable whether Earth was rotating or not. 

Why does a ball thrown straight up in the air fall to the same place on the ground ?

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One
of the profound Aristotelian arguments against the rotation of the
Earth was that if the Earth were rotating, a thrown ball/arrow would not
land in the same place that it was thrown.

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This was believed so
because, by the time the projectile traverses its path the Earth would
have moved by a certain distance. Hence, the ball would never land at
the same place it was thrown.

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Take a second to think about this. Can you come up with an argument against this rationale ?

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Here
is an excellent argument given by Galileo in favor of the rotation of
the Earth and why things would still fall to the same place even if the
Earth were rotating:

In replying to this, those who make the earth movable answer that the canon and the ball which are on the earth share its motion or rather that all of them together have the same motion naturally.

Therefore the ball does not start from rest at all but to its motion about the center joins one of projection upward which neither removes not impedes the former.

You
will see the same thing by making the experiment on a ship with a ball
thrown perpendicularly upward from a catapult. It will return to the
same place whether the ship is moving or standing still

The profundity of this argument is that, the very same principle that ‘ball does not start from rest at all  but with velocity of the earth’ is used by space shuttles to reach orbital velocity with lesser fuel consumption.

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But despite Galileo’s argument, it was still believed for a long time that it were the heavens that moved and not the earth.

For
God hath established the world which shall not be moved in spite of
contrary reasons because they are clearly not conclusive persuasions.

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fuckyeahphysica: The Tale of Earth and it’s sister Theia. Have…

fuckyeahphysica:

The Tale of Earth and it’s sister Theia.

Have you found it weird that the earth’s axis is tilted by 23.5 degrees and wondered what led to this? Wait, Where did the moon come from?

Well, Here’s what scientists have theorized.

The Giant Impact Hypothesis

Theia, a mars sized planet collided ( it glanced and thankfully did not collide head on, else it would have destroyed earth ) with the Earth around 4.553 billion years ago.

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Theia’s debris gathered together around Earth to form what we now call- The Moon.

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The collision between the early earth and Theia was so immense that
it tilted the axis of rotation of the early earth by 23.5 degrees.

And
it remains tilted so that way even today!!

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Why do they believe in this hypothesis ?

Scientists have a very good reason to believe in the Giant Impact Hypothesis:

  • Earth’s spin and the Moon’s orbit have similar orientations.
  • Moon samples indicate that the Moon once had a molten surface.
  • The Moon has a relatively small iron core.
  • The Moon has a lower density than Earth.
  • Evidence exists of similar collisions in other star systems (that result in debris disks).
  • Giant collisions are consistent with the leading theories of the formation of the solar system.
  • The stable-isotope ratios of lunar and terrestrial rock are identical, implying a common origin
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Have a good day !

PC: sarice,

Now not only do we now have an understanding of why the earth is spinning but also why the axis of rotation is inclined by 23.5 degrees.

Stay tuned for more..

Why did the Earth start spinning?

We have been discussing about the rotation of the Earth in the past couple of posts but lets take a second to understand why the earth is rotating in the first place.

Here is a quick summary:

Our Solar System formed about 4.6 billion years ago when a huge cloud
of gas and dust started to collapse under its own gravity.

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As the cloud collapsed, it started to spin. Some of the material
within this cloud gathered into swirling eddies and eventually formed
into planets. As the planets formed, they kept this spinning motion.

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As material gathered in more closely to form a planet, like Earth, the
material spun faster. This is similar to what you see when skaters pull in their arms and spin
faster.

And as a result since there are no forces are acting on Earth to slow it down, it continues to spin to this day. **

** not entirely true as we shall explore soon

Previous posts:

The shape of the Earth is an oblate spheroid: A visual demo

How does earth’s rotation affect space shuttle launches ?