We Have No Idea: A Guide to the Unknown Universe

by Jorge Cham

One totally interesting idea is to try to find something that has already been built for other purposes and adapt it to work as a cosmic-ray telescope.

Such a simulation might have glitches due to the limitations of the computer that is running our universe.

Quantum mechanics forced physicists to abandon deep and simple assumptions about the world: that things cannot be in two places at once or that precisely repeating the same experiment twice should give the same result.

Bring a particle and its evil twin together and expect a lot of drama and a big flash of energy.

equation E = mc2. Note that in this equation the speed of light, c, which is already large at 300 million meters per second, is squared, so a little bit of mass carries a lot of energy.

these particles are quantum mechanical objects, not actually tiny little balls.

Once you have antielectrons, antiprotons, and antineutrons, you could potentially make antiatoms!

the universe seems to have a lot more matter than antimatter.

if there was an antiparticle created for every regular particle, then eventually all the particles would meet with their antiparticles and annihilate each other,

a neutron can decay into a proton, an electron, and an antineutrino (this is called nuclear beta decay and it happens all the time). In just the same way, an antineutron can decay into an antiproton, an antielectron, and a neutrino.

The same is true of general relativity and the Big Bang. Since we don’t have a quantum theory of relativity, we don’t really know how to calculate or predict what was happening in the very early universe. This means that the picture of the Big Bang starting with a singularity is probably not accurate; in those early moments quantum gravity effects dominated, but we have no idea how to describe them.

What if, a few moments after the universe was created, there was a period of about 0.00000000000000000000000000000001 seconds in which the fabric of space-time itself expanded by a factor of about 10,000,000,000,000,000,000,000,000—at a rate faster than the speed of light?102Bam. Problems solved.

The things inside the universe kept obeying the cosmic speed limit (they didn’t move through space faster than light), but according to inflation space itself did expand, making new space faster than light could traverse it.

Where did the quantum inflating blob come from?

Maybe It’s Black Holes All the Way Down

strong force grouped the quarks into protons and neutrons. Electromagnetism pulled protons and electrons together to make neutral atoms. But gravity can’t be balanced or neutralized.

The reason the rock or your venti beverage doesn’t get collapsed into a tiny dot by gravity is that it has some internal pressure from the nongravitational forces.

If you have a bigger mass, say enough to form a planet the size of Earth, the gravitational forces are strong enough to compress the rock and metals of the center into molten lava.

The reason the center of the Earth is hot and liquid is due entirely to gravity.

Thanks to the expansion of space, we can see things that used to be closer to us than they are now. So the observable universe is much larger than the speed of light times the age of the universe. This comprises the universe that we can see today.

Is There a Theory of Everything?

We are mostly clueless about what the universe is filled with (dark matter) and how to describe the most powerful forces that control it (dark energy, quantum gravity).

This is important because the ultimate theory, the one that’s going to make physicists hang up their coats, drop their mics, throw their hands up in the air, say, “Yup, we’re done,” and walk away (probably unemployed) will be the one that describes nature at its most fundamental core.

In order to arrive at a number that defines distances (for example, with units in meters), physicists multiply Planck’s constant with two other constants: the maximum speed of the universe (c, the speed of light) and the strength of gravity (G). If we combine these in a particular way, we can come up with a number that has units of distance.117 This number turns out to be very, very small: 10−35 meters, or 0.00000000000000000000000000000000001 meters.

example, a hydrogen atom is actually a proton with an electron bound together by the electromagnetic attraction between them.

In the same way, a proton is actually made of three quarks bound together by the strong force between the quarks.

So one way to figure out if electrons and quarks are made of smaller particles is to smash them at higher and higher energies. If we reach a smashing energy that is higher than what might be holding the electron or quark together, then they would break apart and we would see that they are made of smaller pieces.

century. James Maxwell noticed that electric currents make magnetic fields, and if you move magnets, you can make electric currents.

The photon, which we all know and love, is actually just one feature of some deeper force that can also produce the W and Z bosons, which transmit the weak force.

twelve matter particles that so far we haven’t been able to break further apart (the Standard Model). And we have a list of three possible ways that these particles can interact (the electroweak and strong forces and gravity).

we have two theories (theoretical frameworks, rather) for understanding the universe: quantum mechanics and general relativity.

we have a great theory for particles that covers most of the fundamental forces (quantum mechanics), and we have a great theory for gravity (general relativity),

in order to make quantum mechanics work in the first place, physicists have to apply a special mathematical trick called renormalization.

We know how to calculate forces in quantum mechanics, but we don’t know how to use it to calculate the bending of space.

If you travel to a foreign country, you will make the charming discovery that there are many differences between the local way of life and your own.

progress.

This is a very simple mathematical formulation (known as the Drake equation), but it’s useful because it breaks the problem into parts and shows that if just one of these pieces is zero then we will never hear from aliens even if they do exist.

astronomers have developed some very clever techniques for indirectly detecting planets. They can look for a small wiggle in a star’s position, which means that the star is being pulled slightly by the gravitational force of a planet. They can also look for periodic dips in the light from the star, which means that the planet orbiting the star is passing in front of it. Using these techniques and others, astronomers have discovered something incredible: about one in five stars in our galaxy has a rocky planet with a size similar to Earth’s and a similar amount of solar energy on its surface. That means that the number of possible Earths just in our galaxy is in the billions.

So we understand very little so far about how life was created from a sterile environment on Earth.

Other places in our solar system might not make your top five vacation destinations, but they are reasonable candidates for hosting life. Jupiter’s moon Europa is thought to have a huge underground ocean, and Saturn’s moon Titan has an atmosphere and oceans of chemicals that could be used to build early life-forms.

Our most powerful radio telescope, at Arecibo in Puerto Rico, could only hear such a broadly sent weak signal if it was within about one-third of a light-year from us.