The Big Freeze

The Big Freeze

The most widely accepted theory is that the universe will eventually come to an end. It will most likely do so trillions of years from now, when the entire span of the cosmos is empty and just a notch above absolute zero. We sometimes refer to this fate as the "Big Freeze."

Why, you ask? Out of respect for the law—specifically, the second law of thermodynamics, which tells us that total entropy (basically, chaos) in the order of the universe always increases. The second law of thermodynamics is one of the supreme laws in all of physics. If a scientist proposes a theory that violates it, he's in big trouble! 

Chaos and disorder: doesn’t that suggest a particularly violent end, rather than a big chill? Well, entropy doesn’t necessarily refer to dramatic destruction; it’s more about how stuff just tends to fall apart. Think about food sitting on your kitchen counter or in your refrigerator for an extended period of time: it will eventually rot. Or your car, which will begin to rust, decreasing its original strength. The example you're most familiar with is the way your body undergoes decline as it ages. Your vision and hearing get worse; you're not as strong as you used to be; your hair thins; you start to see wrinkles; and eventually your bodily processes begin to shut down.

Entropy is unique because it’s the only quantity in the physical sciences that indicates a particular direction for time (the "arrow of time"). It tells us that there is no hitting the rewind button to the beginning of the universe.

So the galaxies of the universe will eventually disintegrate, dead dwarf stars will drift away into the darkness along with the halts of neutron stars, and everywhere there will be black holes. There are an estimated 70 sextillion stars in the visible universe, organized in billions upon billions of galaxies. To put things in perspective, that’s 70 thousand million, or 7 followed by 22 zeros, and about 10 times as many stars as grains of sand on all the world’s beaches and deserts. A number so large, it’s almost impossible for us even to imagine.

Right now, we are in the Stelliferous age of the universe: the period in the life of the universe when there are still stars. Yet when the entire age of the universe is taken into consideration, it turns out that stars burn brightly only for a very short time. A trillion years from today, almost all the stars will have burned up all their nuclear fuel. A trillion years after that, even the black holes will have disintegrated; after that, even the protons themselves will begin to decay. The universe will then become a freezing mist of electrons and eventually approach absolute zero. At this point all motion stops...and that’s the Big Freeze.

Maybe we will be able to leave the universe before it gets too cold... You can watch a video clip of my Big Think interview (How to Escape to a Parallel Universe) which was recently voted one of Big Think's top ten videos of the first 100 days of 2010.

How do you think the Universe will end?

Let's hear your answer in the comments section for a chance to win an autographed 8x10 color photo. To be entered into the contest, simply answer the question (How do you think the Universe will end?) below by posting a comment in the comment box. You have to be a registered user of Big Think in order to post a comment. (REGISTER HERE if you haven't already.)

Winner of the autographed photo will be chosen on May 20th along with the winners from my other contest.

Good luck!

This is what aliens would 'hear' if they flew by Earth

A Mercury-bound spacecraft's noisy flyby of our home planet.

Image source: sdecoret on Shutterstock/ESA/Big Think
Surprising Science
  • There is no sound in space, but if there was, this is what it might sound like passing by Earth.
  • A spacecraft bound for Mercury recorded data while swinging around our planet, and that data was converted into sound.
  • Yes, in space no one can hear you scream, but this is still some chill stuff.

First off, let's be clear what we mean by "hear" here. (Here, here!)

Sound, as we know it, requires air. What our ears capture is actually oscillating waves of fluctuating air pressure. Cilia, fibers in our ears, respond to these fluctuations by firing off corresponding clusters of tones at different pitches to our brains. This is what we perceive as sound.

All of which is to say, sound requires air, and space is notoriously void of that. So, in terms of human-perceivable sound, it's silent out there. Nonetheless, there can be cyclical events in space — such as oscillating values in streams of captured data — that can be mapped to pitches, and thus made audible.


Image source: European Space Agency

The European Space Agency's BepiColombo spacecraft took off from Kourou, French Guyana on October 20, 2019, on its way to Mercury. To reduce its speed for the proper trajectory to Mercury, BepiColombo executed a "gravity-assist flyby," slinging itself around the Earth before leaving home. Over the course of its 34-minute flyby, its two data recorders captured five data sets that Italy's National Institute for Astrophysics (INAF) enhanced and converted into sound waves.

Into and out of Earth's shadow

In April, BepiColombo began its closest approach to Earth, ranging from 256,393 kilometers (159,315 miles) to 129,488 kilometers (80,460 miles) away. The audio above starts as BepiColombo begins to sneak into the Earth's shadow facing away from the sun.

The data was captured by BepiColombo's Italian Spring Accelerometer (ISA) instrument. Says Carmelo Magnafico of the ISA team, "When the spacecraft enters the shadow and the force of the Sun disappears, we can hear a slight vibration. The solar panels, previously flexed by the Sun, then find a new balance. Upon exiting the shadow, we can hear the effect again."

In addition to making for some cool sounds, the phenomenon allowed the ISA team to confirm just how sensitive their instrument is. "This is an extraordinary situation," says Carmelo. "Since we started the cruise, we have only been in direct sunshine, so we did not have the possibility to check effectively whether our instrument is measuring the variations of the force of the sunlight."

When the craft arrives at Mercury, the ISA will be tasked with studying the planets gravity.

Magentosphere melody

The second clip is derived from data captured by BepiColombo's MPO-MAG magnetometer, AKA MERMAG, as the craft traveled through Earth's magnetosphere, the area surrounding the planet that's determined by the its magnetic field.

BepiColombo eventually entered the hellish mangentosheath, the region battered by cosmic plasma from the sun before the craft passed into the relatively peaceful magentopause that marks the transition between the magnetosphere and Earth's own magnetic field.

MERMAG will map Mercury's magnetosphere, as well as the magnetic state of the planet's interior. As a secondary objective, it will assess the interaction of the solar wind, Mercury's magnetic field, and the planet, analyzing the dynamics of the magnetosphere and its interaction with Mercury.

Recording session over, BepiColombo is now slipping through space silently with its arrival at Mercury planned for 2025.

Study helps explain why motivation to learn declines with age

Research suggests that aging affects a brain circuit critical for learning and decision-making.

Photo by Reinhart Julian on Unsplash
Mind & Brain

As people age, they often lose their motivation to learn new things or engage in everyday activities. In a study of mice, MIT neuroscientists have now identified a brain circuit that is critical for maintaining this kind of motivation.

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End gerrymandering? Here’s a radical solution

Why not just divide the United States in slices of equal population?

The contiguous U.S., horizontally divided into deciles (ten bands of equal population).

Image: u/curiouskip, reproduced with kind permission.
Strange Maps
  • Slicing up the country in 10 strips of equal population produces two bizarre maps.
  • Seattle is the biggest city in the emptiest longitudinal band, San Antonio rules the largest north-south slice.
  • Curiously, six cities are the 'capitals' of both their horizontal and vertical deciles.
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Surprising Science

Scientists discover why fish evolved limbs and left water

Researchers find a key clue to the evolution of bony fish and tetrapods.

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