Finally! A black hole that you can visit and survive!
Want a trip through a black hole without having to experience that pesky death? You’re in luck. There’s a special kind of black hole that’s not just survivable, but might get you to another time, or another universe.
Black holes are, traditionally, the scariest things in the universe. Huge, mysterious, inescapable, they wander through the universe and eat everything that gets too close. “Too close” is defined by their event horizon. This is the point at which they go dark, because it requires so much energy to escape them that not even light can get away. Since not even a photon can cross the barrier, no event that happens inside the horizon can ever have an effect on people outside.
Unless, something very odd was going on in the center of the black hole. Most black holes spin - this is something that was discovered way back in the 1960s by physicist Roy Kerr. It wasn’t exactly a shock, because most of the material that collapses into a black hole was already spinning. Sometimes, however, the spin on Kerr black holes goes a little above and beyond. Ever spun a glass of water, or soda bottle, so that the liquid inside swirls? Sometimes, if you spin it enough, the liquid actually parts, leaving a clear center and a spinning ring of water around it. The same kind of thing can happen in Kerr black holes. Instead of a singularity at the center, there’s a ring. And you can go through the open portion of that ring without touching the gravitational crush.
What’s on the other side? A lot of people have wondered. Some people think that these kind of black holes might be our key to time travel. They might be wormholes that let us hop between different points of the universe. Or they might be portals to different universes entirely. First we’ll have to find a few, and then we’ll need a few volunteers to go through. Preferably ones that haven’t seen Event Horizon.
Black holes are a tear in the fabric of space-time from which nothing escapes, not even light. They take on a mythic significance in popular culture as portals to alternate dimensions or grave threats to space travel. Astronomers are certain they exist out there in the universe, formed by the collapse of dead stars.
Now, physicists have found mathematical analogs to black holes here on Earth, specifically in the southern Atlantic Ocean where eddies whirl about. The work was posted to arXiv and reported first by the The Physics arXiv Blog.
The scientists describe the eddies using Edgar Allan Poe’s “A Descent into the Maelström”:
“The edge of the whirl was represented by a broad belt of gleaming spray; but no particle of this slipped into the mouth of the terrific funnel…”
That’s exactly how eddies look, the study says. A belt of spray encircles the whirlpool but the liquid does not fall in.
Similarly, black holes in space are encircled by photon (light) spheres, a region where the gravity is so strong (because of the density of the black hole) that it causes light to travel in an orbit. And there the photons remain, in precarious balance, neither falling into the hole or escaping. That’s similar to Poe’s description of the belt of spray around the Maelström.
And much like astronomical black holes, oceanic eddies exhibit singularity.
To locate these oceanic black holes, the scientists examined satellite images of the Agulhas Current in the Indian Ocean. The current travels along the east coast of Africa before turning back on itself in a loop. The loop occasionally pinches off and forms eddies that whirl off into the South Atlantic Ocean, remaining intact for more than three months.
The eddies are a coherent island of water in an otherwise turbulent ocean. As such, they “create moving oases for the marine food chain or even impact climate change through their long-range transport of salinity and temperature,” the study states. The eddies will capture any detritus floating nearby and swallow it, thereby transporting oil and garbage. And nothing within leaks out.
From Poe’s story again, a description of the his fictional Maelström:
“…whose interior, as far as the eye could fathom it, was a smooth, shining, and jet-black wall of water, inclined to the horizon at an angle of some forty-five degrees, speeding dizzily round and round with a swaying and sweltering motion, and sending forth to the winds an appalling voice, half shriek, half roar, such as not even the mighty cataract of Niagara ever lifts up in its agony to Heaven.”
To get out of the earth’s clutches, we need to travel at least at 11.2 km/s also called the escape velocity.
Similarly, since the gravitational strength of a black hole is so strong, the escape velocity ( if you intend to leave it ) exceeds the speed of light.
Where does it gets it’s gravitational powers?
To understand this, let’s do a thought experiment: What would happen if we compress earth to half its present radius without changing the mass density?
The gravity at the surface would be four times more because of the “inverse square law”. It gets stronger at shorter distances.
And now, say you keep on decreasing the radius even further, the gravity would just keep on spiking to phenomenal levels. This is the secret to the Black Holes extraordinary gravitational powers.
How are they even formed?
All stars follow a life cycle. I will elaborate on the life cycle in another post, since its kind of long. But this illustration from sciteachers would do for now:
Upon reaching a certain critical density, a star will collapse on its own weight. i.e Its radius will keep on decreasing and gravity swooping up at each stage untill it collapses to an almost infinitely small pinpoint.
And that’s how black holes are formed and why they have such a huge gravitational pull on Objects.
Hope you learnt something new about blackholes in this post. This is a series and we will dig deeper as we move down the line. As they say- tiny drops make a mighty ocean. Small baby steps at a time everyday and at the end we will attain colossal clarity! Have a good one.
One of the biggest mysteries in modern physics may have just been solved. The scientific community is abuzz with rumors that
physicists have finally detected gravitational waves, fluctuations in
the curvature of space-time that move at the speed of light throughout
the galaxy. Noted physicist Albert Einstein first predicted them in
1916, theorizing they might explain how mass affects the very fabric of
space-time. The discovery of the gravitational waves would be one of the biggest discoveries in physics in history
No one knew exactly what a black hole would look like until they actually built one. Light, temporarily trapped around the black hole, produced an unexpectedly complex fingerprint pattern near the black hole’s shadow. And the glowing accretion disk appeared above the black hole, below the black hole, and in front of it. “I never expected that,” Thorne says. “Eugénie just did the simulations and said, ‘Hey, this is what I got.’ It was just amazing.”
In the end, Nolan got elegant images that advance the story. Thorne got a movie that teaches a mass audience some real, accurate science. But he also got something he didn’t expect: a scientific discovery.
MORE: Wrinkles in Spacetime: The Warped Astrophysics of Interstellar
Einstein presented his theory of relativity in 1916, but for an entire century nobody could find physical proof of black holes. In 2016, scientists finally detected gravitational waves that emitted from 2 black holes colliding, proving that such things not only exist, but that Einstein was right all along. Source
The simplest kind of black hole is a Schwarzschild black hole, which has mass yet no electric charge or spin. This black hole geometry was discovered by Karl Schwarzschild in 1915, shortly after Einstein presented his final theory of General Relativity. The gifs above are created from a simulation depicting what you would theoretically see if you traveled towards a black hole, against a panorama of our Milky Way.
First of all, as you approach, you clearly see gravitational lensing taking place, with the black hole bending light around it. It appears to ‘repel’ the Milky Way radially, which then stretches the image transversely. The sections closer to the black hole experience greater 'repulsion’, so the image appears to be compressed radially.
You then take note of the Einstein Ring seen around the black hole, occurring because of the bright objects lying directly behind it. Due to the aforementioned gravitational lensing, the light from these bright objects is bent around the black hole and forms this ring.
Fortunately (or maybe unfortunately), as you get closer, the trajectory of your journey does not have enough angular momentum to go into an unstable circular orbit. If you had slightly more, you would find yourself orbiting this black hole, which would, in fact, make for a fairly nice view. However, you carry on travelling towards the center.
Next, you swiftly pass through the photon sphere,where light rays can orbit the black hole in unstable circular orbits. However, you do not see anything of particular interest, but are more concerned with your forthcoming fall through the horizon.
As you travel, you would not know at what point you fell through the black hole’s horizon. However, as you do pass through it unaware, it apparently splits in two, explained nicely by these Penrose diagrams (if you have the chance to give them a quick glance over whilst you’re hurtling towards your inevitable death). Here, space is falling faster than light, meaning you are carried inexorably inward.
Anyone who happens to be watching your spectacular journey would see you as fairly dim and red. This effect is due to red shift, with anything falling past the black hole’s horizon appearing this way to an observer outside of this point.
As you get closer and closer to the center, the black hole’s tidal forces begin to wear on you. Presuming you are travelling feet first, you feel a greater force of gravity in your lower half than up by your head. Due to these forces, you are stretched vertically and crushed horizontally; this is known as spaghettification. These forces also mean that your view of the Universe beyond is blue shifted and bright around your waist, but red shifted and dim above that; a strange sight.
Despite having been utterly torn apart from the tidal forces, a tenth of a second later you reach the black hole’s singularity, the center point of infinite curvature. Here, space and time as you know them come to an end, and so does your exciting journey.
It must be remembered that real black holes are probably much more complicated than Schwarzschild black holes; they likely spin and are not isolated, so a journey into a normal black hole could be slightly different adventure.
The largest ever discovery of water is a massive reservoir that’s floating around a black hole 10 billion light-years away. The water is 140 trillion times the mass of Earth’s oceans and is older than the formation of most of the stars in the Milky Way galaxy.
One hundred years after Albert Einstein predicted the existence of gravitational waves, they have been detected directly.
In a highly anticipated announcement, physicists with LIGO revealed today, on 11 February, that their twin detectors have heard the gravitational ‘ringing’ produced by the collision of two black holes about 1.3 billion light-years from Earth.
This means we now have a new tool for studying the Universe. For example, waves from the Big Bang would tell us a little more about how the universe formed.
read more here
Image credit: Nik Spencer/Nature