Introduction
Our galaxy spans over a hundred thousand light years from end to end, a distance so immense that it defies ordinary comprehension. Even the earliest radio signals sent by humanity, traveling at the speed of light, would only have touched less than a minuscule fraction of the stars in the galaxy.
Faster-Than-Light (FTL)
The speed of light, known as the cosmic speed limit, appears infinitesimal when compared to the vastness of a galaxy, making any hopes of galactic exploration or communication seem unattainable within human lifetimes. Nevertheless, the question has long persisted: could there be a way to exceed this cosmic speed limit and achieve faster-than-light (FTL) travel, popularly known as the “FTL cheat code”?
Alcubierre drive
Human ingenuity has relentlessly challenged Einstein’s cosmic speed limit, seeking a way to achieve FTL travel or communication. Although there is currently no practical FTL system, physicists have explored various theoretical possibilities. One notable concept is the hypothetical Alcubierre drive, inspired by Star Trek’s warp drive. It suggests that manipulating space itself could potentially allow for FTL travel. However, this idea faces numerous challenges, such as the requirement of exotic matter, enormous energy needs, and potential risks, including causality violations and quantum effects.
Quantum Effects
Speaking of quantum effects, incorporating them into FTL systems like the Alcubierre drive poses significant challenges and unresolved questions. Without a complete theory of quantum gravity, these FTL concepts remain speculative and unverified.
The feasibility of FTL remains uncertain due to the existence of multiple FTL ideas, each with diverse proposed mechanisms. Physicists continue to explore new possibilities, and thus, completely excluding FTL as a possibility seems unlikely.
Causality
All faster-than-light (FTL) systems share one clear implication: they permit time travel that violates causality. In other words, FTL travel intrinsically carries the potential to create paradoxes and inconsistencies in the timeline. Although this may seem fantastical, it presents serious challenges to our comprehension of the universe and prompts questions about the very structure of reality.
The prospect of causality violation and time travel paradoxes has sparked debates among scientists. Some contend that the laws of physics must prohibit time travel paradoxes in some manner. Others argue that perhaps causality is not fundamental, and the universe permits paradoxes. Resolving this issue remains an open and complex question.
Regardless, the fact that FTL travel raises the possibility of time travel highlights how such exotic transportation would profoundly impact our understanding of space and time. The implications extend beyond fiction and touch on the deepest mysteries of existence.
The concept of faster-than-light travel raises intriguing questions and challenges our understanding of the universe. While FTL systems are not currently a reality, the pursuit of space exploration without FTL can foster a sense of unity and selflessness, as our efforts would be directed toward the future generations and the collective progress of humanity. As we continue to explore the cosmos, the mysteries of FTL and its potential consequences remain a subject of fascination and exploration.
But why we can not go faster than light?
In the last century, scientists have made remarkable strides in expanding our understanding of the universe, delving into extreme conditions like the microscopic realm, high speeds, and near absolute zero temperatures. However, it is essential to recognize that our intuition about the world only applies to a limited set of conditions.
For instance, the behaviour of matter in the centre of the sun differs significantly from its behaviour on a bright day here on Earth. Understanding and accepting such distinctions can be challenging for some people. Among the extreme realms, the concept of objects moving at super-fast speeds tends to cause the most difficulty for many, as highlighted.
Albert Einstein’s theory of special relativity, published in 1905, brought about mind-boggling implications. For instance, distances shorten, and clocks slow down for objects moving at high speeds.
While the idea of a maximum speed in the universe might surprise those unfamiliar with physics, it is a fundamental truth. Contrary to popular belief, the explanation of mass increasing with speed is not the reason for the speed limit. Instead, the impossibility of surpassing the speed of light arises from two crucial insights: the unification of space and time into a single concept called spacetime, and the constancy of the speed of light for all observers, regardless of their relative velocities.
To illustrate the concept, an analogy is drawn with a car moving on a flat surface. The car can move solely eastward, solely northward, or in a diagonal direction, combining both eastward and northward motion. In relativity, these directions are replaced by spacetime axes, where the vertical direction represents time, and the horizontal direction represents space.
Einstein showed that all objects move through spacetime at the same speed—the speed of light. When an object starts moving through space, it experiences time at a slower rate. As an object approaches the speed of light, time dilation becomes more pronounced, making time appear to nearly stop.
This fundamental insight, proposed by Einstein’s mentor Herman Minkowski, explains why moving through space faster than the speed of light is impossible. The reason lies in the constant movement of objects through spacetime at the speed of light. When an object moves solely through space, it has no more speed to gain, reaching the maximum limit.
While this explanation clarifies the speed limit through space, the reason for the single speed through spacetime remains a mystery. It is considered a fundamental property of spacetime yet to be fully understood.
Conclusion
In conclusion, grasping the concept that objects move through spacetime at a fixed speed—the speed of light—is crucial to understanding special relativity and its seemingly unusual effects. Accepting the unification of space and time as components of spacetime enables a clearer understanding of relativistic phenomena.
References:
https://www.scientificamerican.com/article/is-time-travel-possible/
