How much Joules does a collision of two black holes produce?

 A black hole collision releases roughly 

$5.4\times {10}^{47}$ Joules. For a split second, it radiates 50 times more power than all stars in the observable universe combined—yet emits no light.

Instead, it generates pure energy in the form of gravitational waves: ripples in the fabric of spacetime itself.

When two black holes spiral inward and finally merge, a significant portion of their combined mass is converted directly into energy according to Einstein's $E=m{c}^2$. The first gravitational wave event ever detected, GW150914, involved the collision of two black holes with masses roughly 36 and 29 times that of our Sun. They merged into a single black hole weighing 62 solar masses.

The missing three solar masses were converted entirely into gravitational wave energy in a fraction of a second.

Here is how that $5.4\times {10}^{47}$ Joules figure is calculated:

• One solar mass is about $2\times {10}^{30}$ kilograms.
• The three missing solar masses equal roughly $6\times {10}^{30}$ kilograms.
• Multiplying that mass by the speed of light squared ($E=m{c}^2$) gives the total energy output.

To put this number in context, a typical supernova releases around ${10}^{44}$ Joules over several weeks. Our Sun, burning steadily for its entire 10-billion-year lifespan, will produce roughly $1.2\times {10}^{44}$ Joules from start to finish.

The collision of those two black holes released about 4,500 times more energy than the Sun will generate in its entire existence.

Because this energy was unleashed in just two-tenths of a second, the peak power output was immense.

Yet, because gravitational waves interact so weakly with matter, by the time this wave reached Earth 1.3 billion years later, it merely stretched the four-kilometer arms of the LIGO detectors by a distance a thousand times smaller than the width of a proton.

A computer-generated view of a pair of supermassive black holes orbiting each other, each surrounded by an accretion disk of hot gas. Photo by Jeremy Schnittman is licensed under CC BY 4.0.

Is it possible for us to witness the collision of two distant galaxies in our lifetime, or will it ever occur?

 Right now, telescopes can see distant galaxies violently colliding at millions of miles per hour. Yet if you watched one for an entire lifetime, you wouldn't see a single pixel move.

Galaxies are unfathomably large. The Milky Way is about 100,000 light-years across, and the distances between galaxies are measured in millions of light-years. Because of this immense scale, a single collision takes hundreds of millions to billions of years to complete. To human eyes, these high-speed collisions appear completely static.

The Antennae Galaxies are a pair of spiral galaxies currently undergoing a collision, located about 45 million light-years from Earth. Photo by ESA/Hubble is licensed under CC BY 4.0.

Because astronomers cannot watch a single collision unfold, they study galactic mergers using a cosmic flipbook. By surveying the sky, they find different galaxies caught in varying stages of the process. They observe some pairs just beginning to approach one another, others like the Antennae Galaxies (pictured above) whose gravitational interactions have violently deformed their structures into long stellar "tails", and finally, older systems that have fully merged into a single elliptical galaxy. By lining up these frozen snapshots, astronomers piece together the complete sequence of a collision.

When these structures merge, it is a gravitational dance rather than a physical crash. The spaces between individual stars are so vast that actual stellar collisions are incredibly rare. Instead, the real impact occurs when massive clouds of interstellar gas slam together. The resulting compression triggers fierce bursts of star formation, lighting up the merging galaxies with dense clusters of young, brilliant stars.

The Milky Way is currently on its own collision course with its nearest massive neighbor, the Andromeda Galaxy. Andromeda is rushing toward the Milky Way at 250,000 miles per hour, but because of the distances involved, the two will not meet for another 4.5 billion years.

How could the Titanic have been saved after the collision?

 

At 2:20 AMon April 15, 1912, the Titanic plunged to the bottom of the North Atlantic in 12,500 feet of water.

A fatal collision with an iceberg had doomed over fifteen-hundred passengers and crew to a watery grave, leaving survivors, contemporaries, and historians alike to start question the what if scenarios.

What if the Titanic was slower?

What if the Titanic had more lifeboats?

What if the Titanic had struck the iceberg head on?

Another what if that is not discussed as much is a matter of geography and oceanography: what if the Titanic had sunk in shallower waters?

This may seem like an outlandish scenario, given the depth that the ‘unsinkable ship’ now rests, but it is actually a very poignant question.

It may surprise readers to know this, but it is estimated that a mere seventy kilometres is all that separated the ship from the Grand Banks of Newfoundland.

This is only slighty farther than the Connecticut city of Stamford from Manhattan — the latter being downtown New York City, which the ill-fated steamship would have docked had tragedy not dictated otherwise.

Titanic wreck site (red) in the North Atlantic (dark blue) just south of shallow waters (light blue)

Theoretically speaking, in the 160 minutes it took for the vessel to go down, she could have travelled over 62 nautical miles — or 115 kilometres — giving her more than enough time to reach the vicinity if she had not been sinking.

In reality, she would have probably gone down further, so that was not an option.

So we go to another very real question:

What if Captain Edward Smith had taken the Northern Route instead of the Southern Route?

The Northern Route was about 200 kilometres north of where the Titanic sank, which would have placed her well inside the Grand Banks of Newfoundland.

This was intended to be the original destination of the Titanic — a course that would have actually shortened the voyage by 200 kilometres, due to the smaller circumnavigational sphere the higher north one travels, further disproving the myth that she was attempting to break a transatlantic record — which was only diverted on the day leading up to the sinking when a larger volume of icebergs were spotted in the vicinity.

Iceberg fields were much thicker here, so if she could not avoid striking a block of ice taking the Southern Route, we can “assume” that her luck would run out here as well.

Only she would no longer be facing a watery grave some 3,800 metres deep.

We would be talking about a much shallower grave.

Much shallower.

As in under 100 metres deep shallow.

The Titanic herself was over 270 metres long, meaning the depth of the water even 70 kilometres north of her historical position was barely one-third of her length.

This would have surely prevented her from breaking apart at the surface.

But would it have kept her afloat?

No.

At 100 metres deep she would have probably gone down similarly to the Lusitania — another ship of similar length and tonnage who sank in water of a similar depth.

In this situation, the only thing that may have been to the ship’s advantage is that if the water depth had been even moderately shallower, the stern would not have risen so high in the air, which would have prevented the air from being ejected so quickly during the “final plunge” — likely delaying its demise by at least several minutes or more.

According to some general research I have done, it appears that the bow of the Titanic itself was a little over 18 metres high when, while the boat deck — the tallest part of the ship, minus the funnels and masts — was 29 metres.

Were there any areas in the Grand Banks of Newfoundland that were shallow enough for the Titanic to sail to?

Yes.

Various shoals across the region have been reported to have depths that were under 30 metres, with some areas being as little as 15 metres deep — these are prehistoric islands that were submerged approximately 13,000 years ago during the last great Ice Age.

The Southeast Shoal was the strongest bet, since she was not only the closest major region to the wreck site, her average depth of 40–50 metres would have been only a fraction the length of the Titanic, with some specific spots reportedly having only 15 metres of depth — far more shallow than the height of the bow itself, and nearly twice the height of the ship at boat deck level

If the Titanic had been able to scout a nearby shoal during her doomed hours, she could have potentially survived by not fully submerging beneath the surface — leaving even the bow a little above water in the most shallow spots.

These are a big what if, because there are several reasons as to why it would not have made any practical sense to tempt this in 1912:

1. The Titanic did not have the means to scan the seabed floor with modern instruments
2. Even if the Titanic had found a shallow area, there is no guarantee that currents would not have pushed it back out into deeper water
3. Though hindsight proved otherwise, the Titanic could have just as easily have capsized, as many ships throughout history have done, making this shallow depth practically useless, and wasting precious minutes

In the end, the crew did what was best, given the circumstances and what they knew in 1912.

History is filled with close calls, and the sinking of the Titanic was no exception.

Nonetheless, that question will remain in the minds of those alternative history enthusiasts who will never know the answer one way or another…

What if?

If our solar system somehow got close to another during the Andromeda collision, what would the effects be?

What do you see in the above simulated collision between Andromeda and Milky Way?

Do you see any star smashing into each other? No.

Do you see explosions or physical carnage at the level of individual stars? No.

But, Do you see stars getting flung out? Yes.

See, galactic collisions are galactic level gravitational events, instead of stellar collisions. So mostly stars do not collide (because of unimaginable space in between), but they surely get gravitationally influenced.

If a star could come near to the Sun by around 50,000 AU, it will start flexing its gravitational muscle on. Things would get serious when a star comes closer than 1,000 AU (although very unlikely, but surely possible). That’s when things start to make a carnage a solar system level.

Some so much so that some planets will flung out of galaxy. (Notice how blue object gets effected by other gravitational bodies)

But which ones will be effected, or whether they will be can not be predicted because Galactic collisions are utterly complex processes.

Unimaginable number of highspeed astronautical dynamics can bring on any new threat at any time to the people living in the galaxies (assuming if there are beyond Earth). And by ‘any time’ I don’t mean in matter of days or weeks, but sometimes centuries and millenniums also.

Our Earth has faced a few violent phases in last 4.5 Billions Years. But most of time, it has stayed calm which has given life many chances to evolve. During collisions, this won’t change much, but the number and duration of calm phases are expected to reduce.

What do we mean by calm phase?

Something closer to what we see today, only a beautiful sky.

What do we mean by violent phase?

Quite Possibly .

Earth being flung out would be less likely though, unless extremely unlucky.

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But while thinking about this and discussing this, we mostly forget one important part.

Any possible life, (if there would be) may have shifted to further planets because of increased Solar activity (as sun would also be about to die by that time around.)

Secondly, life would have evolved a great deal by that time. May be it would have started multiple times over by then, so somewhere else in the galaxy or in another galaxy altogether.

We humans take pride in calling ourselves intelligent in mere few 100 thousands years of evolution. By the time this collision would unfold, 3Bn + years would pass on.