Another conversation with ChatGPT

As I said in the previous post, last January I did two sessions with ChatGPT from OpenAI. In the second, my questions were directed to the following scientific topics:

• The special theory of relativity, the limit of the speed of light in a vacuum, and the possibility of traveling in time.

Throughout the session I was asking the following questions:

1. Can a particle travel at a speed greater than light?

Answer: According to the theory of relativity, as first described by Albert Einstein, nothing with mass can travel at the speed of light...

Hyperluminal speed in real life

Cherenkov radiation

We know that the special theory of relativity states that the speed of a body with rest mass greater than zero must be less than the speed of light in a vacuum, i.e., about 300,000 km/second. However, sometimes examples are given that seem to indicate, at first glance, that this limit can be transgressed. Let's look at them:

Superluminal interstellar travel

James H. Schmitz

The human imagination knows no limits. Einstein can tell us that the speed of light sets an insurmountable limit for objects with mass, but deep down we don't believe it. There has to be a way to break that limit! Otherwise, how could we reach the stars during the short span of our lives, return to Earth and tell here what we have seen?

People in our time, especially our civilization, are determined that we must get everything we want. I want to be immortal, so I must be; if I can't, at least my children or my grandchildren. (We don’t usually go beyond our grandchildren…) I want to travel to the center of the galaxy; if I can't, someone will. I want to do whatever I want with my life, so I will… no matter what!

Traveling at the speed of light

Image of
"2001, a Space Odyssey"

Actually, the title of this post is wrong. Traveling at the speed of light is impossible, because it would take infinite energy to accelerate to that speed a body with rest mass greater than zero. What I am going to talk about here is travel at relativistic speeds (close to the speed of light), which means more than 10% of the speed of light (i.e. 30,000 kilometer per second).

Will traveling to the stars be possible?

Will interstellar travel be possible? At the current level of our technology, the answer is clearly no. Will it be possible in the future? It is always dangerous to make predictions: reality often strays from what was supposed to happen. But it doesn't look like interstellar travel is going to become feasible anytime soon. Of course, in the scientific literature, both serious and imaginative, various methods have been proposed, some of which we’ll review in this and future posts, by analyzing the relative probabilities of each one.

Many writers consider interstellar travel the next frontier of human spread, and the only guarantee to avoid our extinction, either accidental, if a cosmic catastrophe occurs, or caused by ourselves with a nuclear war. The problem is, a trip to the stars would be much more difficult than planet exploration in the solar system. Apart from the sun, the closest star to us is 4.27 light-years away, just over 40 trillion kilometers. With our current technique, speeds of the order of one million kilometers per day can be reached, so a trip to that star would last more than one hundred thousand years. Taking advantage of the gravitational pull of giant planets, like Jupiter, it would be possible to triple the speed, but even so we are talking about tens of thousand years.

The v>c world

Albert Einstein

In 1967, Gerald Feinberg game the name tachyon (from the Greek tacus, fast) to hypothetical particles whose possible existence had been proposed five years before by other researchers. Tachyons would have a unique property: they always move at speeds greater than the speed of light. Their mathematical behavior would not infringe the limitations of the special theory of relativity, which prohibits bodies with mass reaching the speed of light. Unfortunately this would cause other problems.

The idea of ​​the possible existence of tachyons was embraced with joy by science fiction writers, for they seemed to make interstellar travel possible in a reasonable time. For this, the following procedure would be effective: