If we want to travel from one star to another, we have many technologies that can take us from one star to another but they will take a long duration to do so. Today, we will talk about the technology that can take us from one solar system to another in a brief period. This technology is called Warp Drive. In the beginning, people understood the Warp Drive concept as hypothetically. People thought it couldn't be achieved technologically, but now such breakthroughs have happened that we will make Warp Drive a reality in the future.
First off, we are going to know Warp Drive and the technological hurdles in this theory that stop us from traveling at the speed of light or even faster than light.
We found the Warp Drive concept for the first time in Einstein's Theory of Relativity. There are some misconceptions that people relate to the Theory of Relativity. According to Einstein's equation, no matter can move at the speed of light neither anything made up of matter can cross the speed of light. But Einstein's Theory of Relativity never rejects the existence of something that travels above the speed of light. Such particles can exist. They will always have to move faster than the speed of light but they can't cross the barrier. These are very important things we should know about Einstein's Theory of Relativity. Einstein's Theory of Relativity permits the concept of faster-than-light, but if an object made up of matter can't move faster than light, then what is the thing that can move faster than the speed of light? This a very important natural question.
We can answer this question with the help of some examples. We have observed things moving faster than the speed of light. For example, when the big bang happened and the universe came into being 13.7 billion light-years before and at that time, our universe became inflated for some time to expand extremely fast. Today, the volume/radius of our universe is 46.5 billion light years. The universe came into existence approximately 14 billion light-years before, so how did the radius of the observable universe become 46.5 billion light years? It is three times bigger than its age.
The first hint is that universe moves faster than the speed of light and scientists believe that it is three times faster than the speed of light.
When we see the farthest massive black hole, we see a redshift there. Redshift means that it is moving away from us at an extremely fast speed and this moving away from us is faster than the speed of light. It means that there was something between us and the massive black hole which moved away faster than the speed of light. So, this was the second such observation in which we saw this phenomenon.
When something crosses the event horizon of a black hole. The event horizon is a circle around the black hole which is considered a dangerous line. Nothing can return once it crosses the event horizon, even light can't escape from it. When something crosses the event horizon, it falls inside the black hole just like something falling from a waterfall, and here things move faster than the speed of light.
In these three examples, the common thing is space. Here, space-time collapses inside the black hole. We also know that our universe is slowly expanding and the space-time is increasing. When we watch the distant massive black hole, it is estimated that space-time is expanding faster than the speed of light and that is why our universe is three times bigger than since its time of inception. So, it means space-time can move faster than the speed of light. Einstein said that nothing could move faster than the speed of light nor anything could cross it but space-time is not a thing. It is a net in which all things exist.
For the first time, scientist Miguel Alcubierre gave the idea of Warp Drive. He solved Einstein's equations and also gave their geometrical solutions and from those equations, he drew the Warp Drive phenomenon. In the beginning, the scientists doubted him a lot and for a long time, nothing significant was done on the Warp Drive Theory. Alcubierre also gave us a model of Warp Drive.
Here we can take an example of a bubble. When a surfer is surfing over the surface of the water, the waves are moving with great speed. Is his skateboard moving or the water under it is moving? If you look at the skateboard, it stands still in its place but the water is flowing so fast that we think the skateboard is also moving alongside. Actually, the skateboard is not moving, it is the water that is flowing the skateboard alongside. It is also like a man sitting in a bus while traveling. The man sitting on the bus is not moving but it is the bus that is moving which is the 2nd law of motion by Newton. We can compare water with space-time. If we make a kind of orientation of space-time that moves with great speed. Anything inside it will move faster than the speed of light.
An orientation of space-time that is made for Warp Drive is shown in the above picture (Figure 1.0). In this orientation, we have a bubble and in front of it, there is a ditch while behind, we have an expansion in space-time. We know that for making a ditch in space-time, we need gravity and energy and we get this gravity and energy from matter. In the picture below, we clearly see a ditch under the sun in the net of space-time.
In Warp Drive, we have a ditch and it can be achieved with the help of matter, but behind this, we see an expansion in the form of a wall. To get this expansion in the Warp Drive, we will have to work hard as we need negative mass or negative energy for it. We never observe negative mass or energy, but we have some kinds of shapes from which we assume that negative mass or negative energy exists.
For example, take a slinky and suppose a rocket is set to travel through it. The rocket will have to cover a distance to reach its end, but if we fix a rocket in it and instead of moving the rocket, we move the slinky to take the rocket to its destination. We know this slinky represents space-time. So, space-time moves faster than light and anything inside it will move along it with the same speed.
What is Negative Matter?
We know that normal matter makes a ditch in space-time, but when we talk about negative matter, it takes space-time in the opposite direction. It expands space-time. It means negative gravity is connected with it. For example, if we make two planets from negative matter, they will repel each other. They will not revolve around each other nor they will collide with each other but they will repel each other due to negative energy. So, negative matter can produce anti-gravity. Anti-matter is not a negative matter. Remember, we never observe negative matter. Gravity associated with anti-matter is positive gravity.
The negative matter is also called exotic matter. When we travel from one place to another with the help of a Wormhole, we have to keep its tunnel open as normal gravity tries to collapse it, but if we put exotic or negative matter inside it, then it remains open and we can return through it. So, if we invent negative matter, it will also help us in the Wormhole. Einstein's equation never bans negative matter or negative energy. Therefore, negative matter or negative energy can exist and that's why NASA is doing intensive research on it to make such spacecraft that will move in Warp Drive. NASA has also released a picture of such spacecraft which it's going to produce in the future for Warp Drive.
There are a lot of problems in making Warp Drive. According to Einstein, we need infinite energy to achieve the speed of light, and according to Alcubierre, we need infinite negative energy to achieve Warp Drive. But a great scientist of NASA Harold White has made such a structure in which we need negative energy equal to minus seven kg of mass only. If we explode 1000 Hydrogen Bombs, we will get this amount of energy which is massive energy but too little as compared to infinite energy. He is still trying to reduce this energy to a minimum and for this, he has changed the design of the whole spacecraft. We will have to attain negative energy if we want to develop this spacecraft.
Intensive research is going to attain negative energy for making Warp Drive and that's why Warp Drive is not a fantasy but it has become a reality now. It is a challenge in the technological world and a lot of people are working on it. We can produce both types of Warp Drives, faster and slower than the speed of light.
Our last hope of attaining negative energy is Dark Energy. Dark energy is an energy that is expanding the universe and it is anti-gravity energy. It is slowly controlling gravity due to which, our universe will expand even faster. 70% of the universe is made up of Dark Energy, but we don't know anything about this energy. We think that we can find negative energy with the help of Dark Energy and if we succeed, we will make Warp Drive in a more efficient way.