When you think about storms, the first things that come to mind are thunder and lightning, which almost always arrive together. As a result, it’s no wonder why so many people believe that sound and light are two parts of the same phenomenon.
Yet, they are actually quite different! In fact, while both have similarities, their origins and properties vary drastically, particularly their speeds. But that begs the question — which one is faster and what causes such a difference between them?
How Fast Does Sound Travel?
In specific conditions, sound is able to reach an impressive speed of almost 3,319 miles per hour. However, it’s important to understand that sound behaves differently depending on the surrounding environment.
For instance, in water, sound can reach the previously mentioned speed with ease. That’s because water is very dense, meaning that its molecules are very close to each other, allowing the fast transmission of vibrations.
Additionally, water is an incompressible medium. As a result, when it encounters a force such as sound, it immediately transfers its energy to nearby particles. This property blends perfectly with water’s density to create the perfect environment for sound propagation.
In contrast, air is not as dense as water. Not only that, but air rarely has a constant temperature, pressure, and humidity, which can all negatively affect the speed and direction of vibrations. Therefore, it’s no surprise that the speed of sound in air and similar mediums can barely reach 767 miles per hour.
And lastly, while sound can travel through all sorts of environments, it cannot exist in a vacuum. The reason behind it is that sound waves are mechanical and, therefore, need a medium to travel and transport their energy.
How Fast Does Light Travel?
When it comes to light, matters are almost completely different. For starters, light is an electromagnetic wave. Thus, it can pass through a vacuum at a speed of 186,000 miles per second or 669,600 miles per hour. Since it’s constant, that number is the generally accepted speed of light and is used in physics to determine the properties of objects in outer space.
However, while light is constant in the void of space, it has similar properties to sound in other environments. More specifically, it can slow down in transparent mediums like water, glass, and air. The ratio by which light reduces its speed is called the refractive index of the environment and is always greater than one.
As an example, water slows the speed of light 1.333 times while also slightly changing its direction. That’s why, if you stick a straw in a glass full of water, you’ll notice that the underwater part of the object will be misaligned when compared to the upper side.
Is There Anything Faster Than Light?
Generally speaking, light is the fastest thing known to man. Yet, some scientists believe that the expansion of the universe is considerably faster than light. That’s due to how space is not susceptible to the laws of physics. Experts have also observed that some galaxies are moving away from the Milky Way faster than light, while space itself is moving along with them.
What About Tachyons?
Tachyons are hypothetical particles that can travel faster than the speed of light. If they do exist, they could offer a way to transport information at unprecedented speeds. However, like many scientific concepts, the community is rather split regarding their existence.
One of the main arguments against tachyons is that their existence would contradict the laws of conservation of energy and momentum. That’s because tachyons would have to move faster than light while also being able to carry momentum and energy.
Some professionals think that tachyons might not actually travel faster than light. They believe that we perceive them faster than light because we can’t actually observe tachyons moving faster than light. This concept is called the Superluminal Paradox.
But all of these theories are still under debate by the scientific community. So, for now, at least on Earth, nothing can beat the speed of light, regardless of the surrounding environment.
Will Humans Be Able to Travel Faster Than Light?
According to special relativity, no object can travel faster than light, and if it can, then that object will move backward in time. That’s why experts theorize that traveling faster than light is the same as time traveling. However, as of today, this is still just a simple theory with minimal evidence supporting it. But since human understanding of the universe is still pretty scanty, scientists can never write off such a possibility.
Why Is Light Faster Than Sound?
At this point, you might wonder why there’s such a big speed difference between light and sound. After all, aren’t they both waves? In reality, it’s almost impossible to compare the two in a fair and accurate way.
Firstly, sound and light are indeed both waves. However, the former is a mechanical wave, while the latter is an electromagnetic wave. Therefore, sound requires a medium in order to travel, which also determines its speed. This requirement is in contrast to light, which can always travel through a vacuum at a constant speed.
Furthermore, the speed of electromagnetic waves, like light, is a fundamental constant of nature. It is a vital part of the fabric of the universe and is the speed with which cause and effect travel. This concept is extremely complex and reducing it to the same level as sound, which is easier to understand and quantify, doesn’t do it justice.
And finally, light has a dual nature, meaning that it can be a wave as well as a particle. As a result, while it usually tends to slow down in water and similar dense environments, it will rarely decrease close enough to the speed of sound.
To Sum Up
Science can be a bit overwhelming, especially if you are just starting to learn about sound and light. However, what you need to remember is that light is the fastest waveform and can surpass the speed of sound in any environment. And while sound is also pretty fast, the surrounding medium is what determines its speed.
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