Let's Understand White Holes

White holes are almost definitely not a real thing that can be found in nature. In theory, white holes are black holes that are going backwards. In theory. A black hole, as you know, is a giant object that sucks stuff into a singularity - a single point of infinite density - from which there is no escape. So a white hole would be an object that expels matter from a singularity and you would never be able to enter it. White holes only exist in math.

But in 2006, we saw an explosion of light out in deep space that we can't explain any other way. It is even weirder than it sounds. In reality, a white hole would violate the second law of thermodynamics. Which says that the amount of entropy in the universe can only stay the same or increase. It can never decrease.

Entropy is often described as disorder, but it's more like a measure of how many different states that particles in a system can be in at any given moment. Like, if you have a piano and you throw it in a woodchipper, you have increased the entropy of the piano. Because a pile of chopped-up piano splinters can be in lots and lots of different configurations while still being a pile of splinters. But these piano splinters can really only be in one, very specific state in order to be a piano.

So, black holes are great at increasing entropy! They are the universe's woodchippers: shredding entire stars into pulp and leaving only a whiff of radiation. But you can't load your pile of piano splinters into the woodchipper and run the thing backwards to get a piano again. That would decrease entropy, which is not allowed. And if white holes existed, that's essentially what they would do.

So why does anyone think white holes might exist in the first place? Well, they were first proposed as a kind of mathematical oddity, because of Einstein’s theories of relativity. One of the many endearing quirks of relativity is that it doesn't care whether you play time backward or forward. If time can go in one direction, it can just as easily go in the other. So if black holes are a thing, then white holes (which are black holes played backward) can also be a thing.

But just because relativity says time can go in both directions, in practice it pretty much sticks to one, as we all know. So even if a white hole did somehow occur, it would be incredibly unstable. Because the universe does not like it when you break the laws of physics. So a real white hole would probably only last for a few seconds before it collapsed in on itself to become a black hole.

Which brings us back to the explosion we saw in 2006. Detected by NASA’s Swift satellite on June 14, it was a huge gamma-ray burst: the highest-energy type of explosion possible, a million trillion times more energetic than the Sun and it lasted for102 seconds. Scientists believe that gamma-ray bursts only last that long during supernovas.

But this one, labelled GRB 060614, didn't have a supernova to go with it. As far as we can tell, it was an explosion of white-hot light that came from nowhere and then vanished. And while white holes remain incredibly, stupendously, ridiculously unlikely that's pretty much exactly what we think one would look like.

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Some physicists have offered other explanations for what it might have been -- like a shock wave from neutron star torn apart by a black hole, or maybe two neutron stars colliding. But events like these only release energy for two seconds at most -- not a minute and a half.

So, White holes in nature are as impossible as a thing can be, while still being technically possible. And until we see another explosion like the one in 2006 that we could hopefully learn more from, we will just have to wait and wonder.

Also Read:- What Would Happen If You Detonate A Nuclear Bomb In Space?

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Origins Of The Universe

The universe is everything from the tiniest particles to the largest galaxies to the very existence of space-time and life. But how did it all begin? The origin of the universe is the origin of everything. Multiple scientific theories plus creation myths from around the world have tried to explain its mysterious Genesis. However, the most widely accepted explanation is the Big Bang Theory.

The Big Bang Theory states that the universe began as a hot and infinitely dense point only a few millimeters wide, it was similar to a supercharged black hole. About 13.7 billion years ago this tiny singularity violently exploded and it is from this explosion this bang that all matter energy space and time were created. What happened next were two major stages of the universe's evolution called the radiation and matter eras. They are defined by key events that help shape the universe. 

First came the radiation era named for the dominance of radiation right after the Big Bang. This era is made of smaller stages called epochs that occurred within the universe's first tens of thousands of years. The earliest is the Planck epoch no matter existed in the universe at this time only energy and the ancestor to the four forces of nature the super force. At the end of this stage, however, a key event occurred in which gravity split away from the super force.

Next came the grand unification epoch named for the three remaining unified forces of nature. This epoch ended when one of those forces called strong or strong nuclear force broke away. Then the inflationary epoch began during which the universe rapidly expanded, almost instantly it grew from the size of an atom to the size of a grapefruit. The universe of this time was piping hot and it churned with electrons quarks and other particles.

Then came the electroweak epoch when the last two forces electromagnetic and weak finally split off. During the next stage the quark epoch all of the universe's ingredients were present however the universe was still too hot and dense for subatomic particles to form. Then in the Hadron epoch the universe cooled down enough for quarks to bind together and form protons and neutrons. In the lepton and nuclear epochs, the radiation era's last two stages, the protons and neutrons underwent a significant change they fused and created nuclei and in doing so they created the first chemical element in the universe helium. 

The universe's new ability to form elements the building blocks of matter cued the matter era. Much as the name suggests the matter eras defined by the presence and predominance of matter in the universe, it features three epochs that span billions of years the vast majority of the universe's lifespan and includes the present-day. 

The first was the atomic epoch in this stage the universe's temperature cooled down enough for electrons to attach to nuclei for the first time called recombination. This process helped create the universe's second element hydrogen. This hydrogen along with helium atoms dotted the universe with atomic clouds. Within the clouds small pockets of gas may have had enough gravity to cause atoms to collect, these clusters of atoms formed during the Galactic epoch became the seedlings of galaxies. 

Nestled inside those galaxies stars began to form and in doing so they cued the latest and current stage of the universe's development the stellar epoch. The formation of stars then caused a tremendous ripple effect and helped shape the universe as we know it. Heat within the stars caused the conversion of helium and hydrogen and to almost all the remaining elements in the universe. In turn those elements became the building blocks for planets, moons , life and everything we see today. 

This ecosystem of everything was only possible because of the many stages in the universe's development. While countless questions about the origins of our universe remain, It is only a matter of time for some long sought answers to emerge.

Also Read:- The Seventh Planet From The Sun: Uranus

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Venus Spins Backwards, But Why?

After studying the solar system for hundreds of years, you would think we, at least, have the basics figured out, stuff like why planets spin and orbit the way they do. Except, we totally don’t. And you only have to look at the planet next door to see it.

When scientists began observing Venus in detail in the 1950s and ‘60s, they expected it to be pretty unremarkable. Instead, it turned out to mostly be an inferno of acid rain, one that, of all things, spins backwards! It’s been more than 50 years since then and while we know a lot more about Venus’s climate, we still aren’t totally sure why it’s rotating the wrong way. But we at least have some ideas.

In astronomy, a backwards spin is called retrograde rotation and “backwards” is defined relatively. Because the solar system formed from one cloud of spinning gas, the planets all orbit in the same direction: counterclockwise, if you are looking down on the Earth’s north pole. They also rotate on their axes the same way they orbit, so also counterclockwise. Except for Venus and Uranus. Uranus sits sideways on its axis, probably thanks to a couple of collisions. Venus, meanwhile, rotates clockwise, and it is much less clear why! 

One of the earliest hypotheses was that Venus may have been hit so hard by an asteroid that it reversed direction. The hypothesis seems to have been thrown out there in 1965 by two scientists who worked with the original radar data. And when I say, “thrown out there,” I mean it. They followed up the suggestion by saying, and I quote, “The possibilities are limited mainly by one's imagination; supporting evidence is rather harder to come by.” Which is super convincing.

Either way, when you math it out, the idea kinda falls apart. It turns out that anything big enough to reverse Venus’s rotation would also destroy the planet. The impactor’s kinetic energy would be some 10,000 times too high. So, the impact idea was pretty much shelved.

Thankfully, it was replaced by a few actual evidence-based hypotheses. One of the leading one, proposed around 1970, is that Venus spins the same way it always has. Just at some point, it got turned upside down! This could have happened because of processes within Venus’s interior and atmosphere.

Venus is differentiated, meaning that it has layers like the Earth does: a core, a mantle and a crust. As the planet rotates, the core and mantle can experience friction where they meet. Venus also has a really thick atmosphere, which, thanks to the Sun’s gravity and heat, experiences tides along with the rest of the planet. This hypothesis says that the core-mantle friction and those atmospheric tides could both put some torque on the planet and that instability could have flipped Venus over. Some models suggest this might work only if Venus formed with an initial tilt of about 90 degrees, but others show that it might work with less initial tilt.

Either way, the idea is pretty weird and thinking about an entire planet flipping is kind of mind-boggling. But we have other ideas, too. Another one, first suggested in 1964, is that Venus may have gradually slowed down and then reversed direction. This could’ve been triggered by a few things, including interactions with the Sun’s magnetic field or those atmospheric tides or a combination of both. Venus’s atmosphere would have been the first part of the planet to start rotating retrograde after that spin-down. Then, that may have provided the rest of the force necessary to get the whole planet going backwards. As a bonus, this idea would also explain why Venus’s days are so long.

But there is no clear winner between these two hypotheses yet. To figure out which idea is most likely, we have to know more about Venus’s early dynamics, specifically its rotation rate and axial tilt.

According to a 2001 paper published in Nature, the axis-flip mechanism is most likely if Venus had a rapid initial rotation rate. But if it rotated slower than once every four Earth days and had a relatively small tilt, like less than 70 degrees, then slowing down and reversing is the most probable mechanism. Unfortunately, it is kind of hard to get evidence about Venus from four billion years ago. So until we build a time machine or at least some really good models, the jury is out.

Of course, that is not the whole discussion, either. Because just to throw a wrench in things, that 1960s impact hypothesis is actually making a comeback. Or at least, a version of it. In 2008, one researcher suggested that Venus may have gotten its weird spin back when it was a planetesimal. They argue that billions of years ago, another object about the same size slammed into it and sent it spinning like a backward top. But instead of destroying baby Venus, those two pieces came together to form a full-sized planet. 

Unlike in the ‘60s, there’s actually some potential evidence for this now. Based on Venus’s topography, we don’t think there’s a lot of water in the planet’s interior compared with Earth’s. And a huge impact could have provided the energy to get rid of it. This hypothesis would explain why Venus is so dry, but there are other competing models, too. Like, it’s possible Venus lost its water through evaporation instead.

To learn more, it would help to do a mineralogical survey of the planet to determine if there are any water-containing compounds there. If there are, it means Venus couldn’t have lost all its water so early in that big impact. But we haven’t done one of those yet, because Venus is a place where robots go to die. The good news is, it is arguably easier to build a Venus-resistant rover than a time machine. So hopefully we can get some evidence for at least one of those hypotheses soon.

Also Raed:- 5 Unsolved Mysteries About Our Solar System

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