Which of The Following Cannot Travel in a Vacuum?

The vacuum cleaner is a widely used tool for cleaning things nowadays. Do you know the scientific definition of a vacuum? If you don’t, here is what it means: vacuum is a space where there is no air. The environment we are living in is filled with air. If you are wondering about which of the following cannot travel in a vacuum, keep reading the article.

In the below part of the writeup, we will discuss which of the thing cannot travel through a vacuum. We will also give you detailed information so you can easily understand everything. Keep reading the article to find out all the information.

What is Vacuum and What Happens in Vacuum

As we said above, a vacuum is a space where there is no air or molecules. All the things in the world are consist of mass and they require some sort of space. Scientifically, they are known as matter. You might be shocked to know that even the air is a kind of matter. So, the empty space in the world is not a vacuum.

You might have a lot of empty boxes in the home. But are they really empty? Well, they are not. When there is nothing else in a box, there is the air inside it. If there were no air, it would be a vacuum. The world we are living in consists of an atmosphere and there is air in it. Even inside the empty boxes, there is air. But you might use a vacuum pump to suck out the air from the boxes.

This will make the box some sort of vacuum. But still, there will be some sort of air molecules inside it. As a result, a perfect vacuum is not possible. When you suck out the air from and seal the box, it will be a bit like a vacuum. And, when it becomes a vacuum, there will be no pressure inside it. To create a perfect vacuum, you will require making the pressure 0 PSI.

Some examples of the vacuum:

  1. Space is considered a vacuum (although not always).
  2. The inside of some of the lightbulbs is in a vacuum.
  3. Compared to the earth, the atmosphere of the moon and Mars can be considered a vacuum.
  4. The thermosphere of the earth can be considered a vacuum.

Which of The Following Cannot Travel in a Vacuum?

Sound is something that cannot travel through a vacuum. Well, you first need to know how sound travels to understand why it cannot travel through a vacuum. Below, we will let you know how sound works.

How Sound Works

Sound travels as waves. As an example, when you through rock in a pool or pond, it creates some ripples. The ripples travel around the pool starting from the center where the stone is thrown. Another example can be the rubber band. Hold a rubber band tightly and then pluck it in the middle of the band. This will start vibrating and you will feel the vibration. Sometimes, you will also hear a tickle sound when the vibration happens.

Do you ever sit or stand next to a big speaker that produces a lot of noise? Well, if the answer is yes, you have might feel a vibration too. This might make you wonder that sound is somehow connected to the vibration. Well, you guessed it right, to make sound, you need to produce vibration. They are actually known as vibrations sound waves. When you make the sound, it vibrates the nearby objects and then the nearby objects vibrate it surrounding objects.

It is more like the ripple we have mentioned above. By vibrating the surrounding water, the ripple spread out the whole pond. And, so do the sound by vibrating the surrounding objects. Actually, the object here is the air in our atmosphere. The waves become weaker as it goes forward, this is why the sound will be lower after a certain distance.

Now you might wonder whether the sound how the sound travel through solid objects. The answer is the object must have particles to bounce off to vibrate the next object. If it is not available, then you might not hear the sound. Such as, you will hear the sound a bit when you produce it underwater. As the air particles can bounce better, the sound is more influential in the air.

So Why the Sound Can’t Travel Through Vacuum and Space?

The short-cut answer is there is no object or particles or the air like the outside environment in the vacuum. As a result, the sound cannot travel through a vacuum. The perfect example of a vacuum is space. There is essentially zero air in there. As a result, nothing is there to produce the vibration that is needed to move the sound. So, the sounds don’t move.

You will be shocked to know that if you are in one spaceship and if another spaceship just blasts outside, you will not hear the sound. Even you will not hear the exploding, crashing, and other things that happen in the space on a regular basis. Two astronauts can hear each other inside the spaceship that is because it is filled with others. But as soon as they go outside, they will not hear each other.

Light Can Travel Vacuum but Why Sound Can’t?

Now you might be wondering that the light can travel through a vacuum but why sound cant? Well, the main reason behind this is sound and light travel in completely different ways. The photons in the light can act as both particles and waves. As a result, they don’t need a medium of propagation. That means the light can travel through the vacuum and the air at the same speed. It doesn’t require vibration like sound.


If you have been wondering what cannot travel in a vacuum, we hope that this article will help you to solve the mystery. As we discussed above, it is mainly because sound requires to produce vibration to travel but it is not possible in a vacuum. That is why sound cannot travel through a vacuum.

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