Imagine a black hole the size of a coin suddenly appearing near you. What would happen? The short answer is grim: you would not survive. However, the specifics of your demise depend on whether the black hole has the mass of a coin or the diameter of one.
Consider a scenario where a US nickel, weighing approximately 5 grams, collapses into a black hole. This black hole would have an incredibly tiny radius of about 10-30 meters. To put this into perspective, a hydrogen atom measures about 10-11 meters. Thus, this black hole would be as minuscule compared to an atom as an atom is to the Sun.
Such a small black hole would have an extremely short lifespan, evaporating through Hawking radiation in just 10-23 seconds. During this fleeting existence, its 5 grams of mass would convert into 450 terajoules of energy, resulting in an explosion three times more powerful than the atomic bombs dropped on Hiroshima and Nagasaki combined. In this scenario, not only would you perish, but the coin would also be obliterated.
If the black hole had the diameter of a common coin, its mass would be significantly greater, surpassing even that of Earth. Such a black hole would possess a surface gravity a billion billion times stronger than our planet’s. The tidal forces would be so intense that they would tear your cells apart before you even realized what was happening.
While the fundamental laws of gravity remain unchanged, the gravitational experience around such dense objects would be vastly different. The gravitational pull extends across the observable universe, weakening with distance. On Earth, your head and feet are roughly equidistant from the planet’s center. However, standing on a nickel-sized black hole, your feet would be hundreds of times closer to the center, subjecting them to a gravitational force tens of thousands of times stronger than that on your head, effectively ripping you apart.
The devastation wouldn’t stop with you. This black hole would become a dominant gravitational force in what could be termed the Earth-Moon-Black-Hole-of-Death system. One might assume the black hole would sink to Earth’s core and consume it from within. Instead, Earth would move towards the black hole, bobbing around it as if in orbit, losing mass with each pass—a truly eerie scenario.
As Earth is gradually consumed, it would collapse into a disk of hot rock orbiting the black hole. By the time the feeding frenzy ends, the black hole would have doubled its mass, and the Moon’s orbit would become highly elliptical. The solar system would experience profound effects, with tidal forces potentially disrupting near-Earth asteroids and parts of the asteroid belt, sending debris careening through space. Impacts could become a frequent occurrence for millions of years, while the planets remain largely in their orbits.
Ultimately, the black hole that was once Earth would continue orbiting the Sun, taking Earth’s place. In this scenario, you would also meet your end.
This exploration into the hypothetical consequences of a coin-sized black hole was inspired by a question on the AskScience subreddit and the insightful response by Matt Caplin. For more fascinating content, visit his blog, Quarks and Coffee. Join the discussion on our subreddit or learn more about black holes and neutron stars by clicking here.
Special thanks to our supporters on Patreon for making this bonus video possible!
You’ll use a computer simulation to visualize the gravitational effects of a black hole with different masses and diameters. As you run the simulation, observe how objects behave when they approach a black hole, and make sure to record your observations. This will help you understand how the gravity of a black hole influences nearby objects.
In this classroom experiment, you’ll demonstrate energy conversion. Using a small-scale model, you’ll calculate the energy released when a mass is converted into energy, and then compare it to the 450 terajoules released by a black hole. This hands-on activity will help you connect the concepts of mass-energy equivalence and the immense power of black holes.
You’ll calculate the gravitational force exerted by a black hole with the mass of Earth and compare it to the force exerted by Earth itself. This activity will deepen your understanding of tidal forces and how they affect objects near a black hole, giving you insight into the intense gravitational pull of these cosmic phenomena.
Let your imagination run wild as you write a short story or diary entry from the perspective of someone experiencing the effects of a coin-sized black hole. This creative exercise will allow you to explore the scientific concepts you’ve learned in a fun and imaginative way.
You’ll take part in a classroom debate about the potential long-term effects if a black hole were to replace Earth in the solar system. You’ll need to research and present arguments on how this scenario could impact other planets and celestial bodies. This debate will challenge you to think critically about the consequences of such a drastic cosmic event.
Black Hole – A region in space where the gravitational pull is so strong that nothing, not even light, can escape from it. – Scientists study black holes to understand the extreme conditions of gravity in the universe.
Mass – A measure of the amount of matter in an object, typically measured in kilograms or grams. – The mass of an object affects how much gravitational force it exerts on other objects.
Gravity – The force that attracts two bodies towards each other, proportional to their masses and inversely proportional to the square of the distance between them. – Gravity is what keeps the planets in orbit around the Sun.
Energy – The capacity to do work or produce change, existing in various forms such as kinetic, potential, thermal, and more. – The energy from the Sun is essential for life on Earth and drives weather patterns.
Radiation – The emission or transmission of energy in the form of waves or particles through space or a material medium. – Astronomers use radiation from distant stars to learn about their composition and movement.
Explosion – A violent expansion or bursting with noise, often releasing energy rapidly. – A supernova is a massive explosion that occurs at the end of a star’s life cycle.
Earth – The third planet from the Sun in our solar system, home to diverse life forms and ecosystems. – Earth’s atmosphere protects us from harmful solar radiation and helps regulate temperature.
Orbit – The curved path of an object around a star, planet, or moon, especially a periodic elliptical revolution. – The Moon’s orbit around Earth takes approximately 27.3 days to complete.
Tidal – Relating to the rise and fall of sea levels caused by the gravitational forces exerted by the Moon and the Sun. – Tidal forces can cause significant changes in the Earth’s oceans, leading to high and low tides.
Asteroid – A small rocky body orbiting the Sun, mostly found in the asteroid belt between Mars and Jupiter. – Scientists monitor asteroids to assess any potential threat they might pose to Earth.
