From Time to Time Trivia Quiz

Answer: He actually arrives home before he leaves

Going close to the speed of light would not cause Bob's time to move backward. Assuming Einstein's Special Theory of Relativity is correct, it would be impossible for astronaut Bob to go back in time. Einstein theorized that the closer an object's velocity approaches the speed of light, the slower time would actually pass for the fast object relative to a stationary object.

Indeed, more time would pass for the stationary object (i.e. people on Earth) compared to the fast traveling spaceship. Einstein's theory also states that as an object approaches the speed of light, the object's mass would approach infinity, thus preventing anything with mass from actually reaching the speed of light.

In reality, the increasing mass would prevent astronaut Bob from approaching the speed of light in the first place, as it would take a prohibitive amount of energy to accomplish such a velocity for Bob's spaceship.

Answer: Hitting the target would seem instantaneous

It is hard to fathom, but if we did indeed travel at light-speed we would instantaneously travel anywhere in the universe. However, for all observers of the photon in this question, 5 years would pass from the time of emittance to reaching the target. For the observer, light appears to be traveling at about 300,000,000 meters per second or about 671,000,000 miles per hour in a vacuum.

A parsec is the preferred measurement of distance (not time) used by astronomers to calculate the distance between stars and our solar system and is equivalent to about 3.26 light-years.

It is generally believed that all wavelengths of light travel at the same speed, although a few physicists have postulated there could be a nanoscopic difference between wavelengths.

Interestingly, regardless of how fast an observer is traveling, light will always appear to be going away from the observer at light speed ... so astronaut Bob would never catch up to the light emitted from his spaceship, even if he were going light-speed! The special effects of the light speed warping in "Star Wars" is regretfully inaccurate, as well as the idea that time actually passed on the Millennium Falcon while traveling at light-speed! Alas, another childhood belief crushed by physics.

Answer: An object's mass

Einstein turned Newton's theories upside-down by suggesting gravity is not an actual force. He proposed that all objects will travel in straight lines; however, space and time themselves bend when an object with mass is present, causing the illusion of gravity. General Relativity also suggests that the curvature of space-time will also bend the path of a massless photon.

This is significant because Newton depended on there being a force between two masses attracting one mass to the other, meaning a massless photon should not be subjected to gravity if Newton were correct. Einstein was proven right after he correctly predicted the precise location that stars would appear during a solar eclipse.

As for "the hand of God", well it has been known to alter the outcomes of the FIFA World Cup before...Vamos, Vamos Argentina!

Answer: Less total time elapses on a satellite day relative to an Earth day

The amount of time for the satellite to complete an Earth day is slightly less than an Earth day. If this small difference in time is not taken into account, the GPS system would be off by several miles within just the first day! As a result, the satellite would quickly become useless space junk.

The satellites are close enough to the ground that there is not a significant enough delay in signals to render the device inaccurate for most functions. As for the angular momentum, it is fixed once in orbit, unless acted on by another force.

A satellite orbiting the Earth is affected by other massive bodies like the sun and to a lesser extent the moon. However, the total effect is so small that the occasional tiny thrust propulsions needed to keep the satellite in the desired orbit are called "mouse farts" because the force is so tiny! The distance and mass of Pluto would not be enough to affect an Earth satellite.

Answer: Time would go backward

There are so many things that would go wrong for Astronaut Bob here! Just like traveling at light speed will not cause time to go backward, neither does approaching a black hole. As a mass increases to the magnitude of a black hole, the relative time actually slows for Astronaut Bob relative to an outside observer.

The mass of the black hole stretches space-time to the extent that, from Bob's perspective, the black hole would be racing ahead of him as the amount of time to reach the center would stretch to infinity. Think of a carrot on a stick, dangling in front of a donkey. To the outside observer, Bob's ship would disappear as soon as he passed the Event Horizon where light cannot escape to show the observer Bob's ship. Of course, there is the very serious problem that the force of the black hole's extreme gravity would spaghettify Bob long before he even reached the Event Horizon. Thankfully, this is a hypothetical flight and no real Astronaut Bobs were harmed in this experiment!

Answer: Time flows at a variable rate in General Relativity but at a constant rate in Quantum Mechanics

General Relativity explains beautifully the "very big", like stars and galaxies, where space-time dilates predictably based on mass. However, on the quantum scale, the rate of time is not variable. General Relativity assumes space and time can be infinitely divided.

However, the math of space-time stops working once it reaches the scale of Planck's width. While the Planck width is incredibly small, it is not zero. As opposed to applying quantum mechanics at the galactic scale, gravity becomes so massive the universe would collapse into a black hole.

The development of a Quantum Gravity field is one of the most exciting areas of theoretical physics research. By the way, if entropy went to zero everything in the universe would slowly approach the temperature of absolute zero, where even atomic vibrations would begin to break down.

The universe would be dead.

Answer: There are 10 dimensions of space-time

Super String theory settled upon there being 10 dimensions to the universe. The theory is based on the idea that everything in the universe is actually made up of tiny one-dimensional strings that vibrate. The frequency of the string vibration determines what the string actually does, such as form a quark or a lepton.

The theory allowed for compatibility with General Relativity by having a specific vibration frequency to result in a theoretical particle called a "graviton" which would account for the force of gravity.

Inconsistent results over time have led to Super String Theory no longer being considered probable by most physicists, including the lack of discovery of an actual graviton particle.

Answer: Minimum mass unit

Loop Quantum Gravity does not define a minimum mass unit, which makes sense considering photons do not have mass but they do occupy space. It does suggest Planck's width, which is really small at 10 to the minus 35 meters, as the minimum length. The minimum area and volume simply use the minimum lengths for the sides of the square and cube.

The minimum time is listed as 10 to the minus 43 seconds which is a really small unit, but it is not zero. These minimums allow the universe to be divided up into tiny interconnected loops that could expand and bend as space-time requires.

While this theory is fascinating, trying to verify such a tiny segment of space and time is problematic.

Answer: Particle communication is instantaneous making it faster than the speed of light

Quantum entanglement is the wild west of an already wild field of study. Einstein called quantum entanglement "spooky action at a distance" because it appears to occur instantaneously, once observed, resulting in communication between entangled particles occurring faster than the speed of light. Imagine if you flipped a coin here on earth and it ended up heads while an entangled coin in the Andromeda galaxy would show up as tails at the exact same moment.

While quantum entanglement seems impossible, it keeps getting validated by experimental observation. One of the truly cool things about particles, in general, is the observer is a critical determinant of where the particle is in space. Imagine if your child was a cloud of probability between the kitchen and the couch, and only appeared on your couch because you observed their position. Spooky action indeed. Maybe we really do create our own universe...Check out Heisenberg's Uncertainty principle on cool effects of quantum observations.

Answer: They are fragile

Quantum computers will have a huge place in the future but are still too fragile to have a practical place in everyday computing. Particles being in superposition is the reason why quantum computers are so powerful. An ordinary computer relies on ones and zeros to process information.

A quantum computer has the added option of superposition allowing both a one AND a zero to exist simultaneously which exponentially increases processing speed. Encryptions that take ordinary computers years to decode could take quantum computers just minutes. Financial transactions depend on ordinary encryption which would not work against a quantum computer. Given the immense power of quantum computers, they will eventually dominate the geopolitical world. Countries that have reliable access to the processing speed and power of a quantum computer will have an absolute advantage over countries that do not. On top of ordinary computer secrets being easy to discover, in theory, quantum computers would be able to use quantum entanglement to prevent their own encryptions from being broken.

It would be impossible to spy on a quantum computer as the act of observing would alert the system to the spying and allow re-encryption. Quantum computing is a critical area of study and could possibly be the next global arms race.