Figure 1: Image showing the Alcubierre Warp Drive
Our theoretical description of space is the entire observable universe that extends 13.8 billion light years (because the universe is 13.8 billion years old) in any direction we look (and is the same from any observation point in the world). universe, since the universe is infinite). But how much have we explored? The greatest distance reached by a machine, Voyager I, is the outskirts of our Sun, which is a few light hours from Earth, which took 35 years to navigate empty space, at an astonishing speed of 1100 km/s. Humans, on the other hand, have not gone further than the Moon (360 thousand km away from Earth) and are soon planning a trip to Mars. The closest star to our solar system is the Proxima Centauri System, which is about 4.2 light years away, which would essentially take the fastest machine ever built (The Voyager Satellite) to about 76,000 years, the which is not an inspiring number, given that the average life expectancy of a human being is around 60 to 70 years (as of now).
The human species may have originated on Earth, but to ensure the survival of our race we may have to venture out in search of a new home in the stars or scour the universe to find other forms of life or to gain a deeper understanding of the origins and dynamics of the universe. To perform any or all of these tasks we would need a means of transport that travels at a speed that would be a significant fraction of the speed of light or even more for greater distances. But is the speed of light barrier breakable? If not, then why?
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The speed of light and Einstein's theory of relativity
The speed of light is about 300,000 km/s and is the speed at which light (which is an electromagnetic wave) travels through a vacuum. Albert Einstein presented a thought experiment that led him to postulate the theory of general and special relativity. He questioned whether a person holding a mirror at arm's length and traveling in a ship moving at the speed of light could see his own reflection. If he is traveling at the speed of light, the light coming from his face will not have time to cover the additional distance between him and the mirror and back to his eyes, making him invisible to the mirror. This led to a breakthrough in discovering that the speed of light is the true constant of the universe and cannot be broken by any body containing mass. Instead, time increases to slow down a body approaching the speed of light. This could be understood by Einstein's famous equation (which he formulated from this idea), E=mc 2 , which actually means that mass is just energy that has been compressed by a large amount (the magnitude of the square of the velocity of the light) and therefore means that mass cannot cross the speed of light barrier since it cannot go faster than itself (since mass is energy). Therefore making the speed of light the true constant of the universe, as opposed to the length of time being constant (making time travel possible).
Fig. 2: Figure showing the Space-Time Continuum with Gravitational Stretching Effect
2. Space-Time Fabric
Three-dimensional space and time are theorized as an intertwined mathematical model called Space-Time. It is a continuum (homogeneous throughout the universe) and is necessary to better understand many important physical properties that occur in the universe, such as gravity. The three dimensions of space and one dimension of time (past, present and future dimensions) therefore construct a four-dimensional space-time model. Every thing that has happened, is happening and will happen is located along the space-time continuum which consists of its spatial location located along a strand of the past-future line.
Spacetime is referred to as the spacetime fabric due to its elastic nature, meaning it can be stretched by certain physical phenomena. Gravity is a property that causes a stretching in the structure of space-time, which explains why smaller physical bodies revolve around larger bodies in space, like the Earth revolves around the sun, because the sun, being more massive, stretches the fabric of spacetime to a greater extent than the earth, which causes the earth to rotate around the sun to avoid falling into it. This can be understood by placing a football on a stretched cloth and making a small marble rotate around the ball. If the marble doesn't spin around the soccer ball, it will fall into it.
3.The Alcubierre tour
Fig. 3: Graphical presentation of space-time deformation
Alcubierre Street
The Alcubierre impulse, proposed by Mexican physicist Miguel Alcubierre in 1994 and derived from Einstein's equation that describes the formulation of space and time of the four-dimensional space-time fabric in the general theory of relativity. It utilizes the fact that spacetime can be stretched to get around the speed limit of the universe. By stretching the space-time fabric such that it compresses in front of a spacecraft and expands behind it, creating a gravitational wave that the spacecraft can ride, which would appear to be traveling faster than light from a frame reference taken outside the gravitational wave. This gravitational bubble, in essence, would not be violating the speed of light, but would be adjusting the space-time continuum so that space and time compress in front of the spacecraft, which would relatively increase the speed of light in that frame of reference and Also the spacecraft would ride this wave like a surfboard on the tide. In effect, the spacecraft would travel the distance at superluminal speeds, which would greatly help us in carrying out interstellar travel.
Fig. 4: Graphic image showing a ship sailing on the Alcubierre Warp Drive
One question that would arise is what effect will occur within the bubble where the spacecraft and crew are present? If there was a stretching of spacetime, would the crew have endured the stretching of spacetime? This is not true, especially since the warp bubble would have a normal spatial zone between the expansion and compression wavefronts, which would be free from any tidal forces that were present. Due to the presence of the distorted fields, there is a gravitational effect on the spacecraft, causing it to be in continuous free fall, but the crew would not experience any inertial effects such as G-forces. The wave would require the production of a negative energy density by behind it, which would require an exotic matter energy source. The space-time field of the warp drive is described by the so-called Alcubierre Metric, which is defined in the context of General Relativistics.
Figure 5: Effect of continuous stretching on a subject's movement
Fig.6: Gravitational Bubble
4. Current Progress
Fig. 7: Graphical presentation of the bubble in the shape of a modified torus
Although it seems reasonable, the elasticity of spacetime is much lower, which would mean it would require a lot of energy. The first calculations for creating a warp bubble resulted in a rather grim number equivalent to the energy equivalent to the mass of the planet Jupiter (1.9 x 10 27 kg). Therefore, the warp drive idea was initially dismissed by scientists. But in 2012, NASA physicist Harold White and his team began work on the Alcubierre warp drive, which took the aeronautics world by surprise. He proposed a design that would alter the geometry of the warp bubble, which could reduce the energy requirements for generating the warp bubble. The initially ring-shaped warp bubble in which the spacecraft would be placed, if replaced by a thicker, curved Alcubierre ring (shaped like a donut or torus) could greatly reduce energy consumption, according to White, which reignited interest in considering it as a candidate to boost interstellar travel. They are currently conducting tests on a modified Michelson-Morley Inferometer that has two legs, of which a small bubble would attempt to be induced into one of the legs, which would cause it to stretch. Therefore, the concept would be proven if there was a change in the lengths of the test leg in relation to the other.
Fig.8: Photo of Michelson-Morley Infero Test Device
5.Problems faced
There would also be certain problems that would be associated with the development of the AD engine, one of which would be that it would be out of communication with any source outside the bubble, since the local change in the speed of light would cause interference. The spacecraft cannot be maneuvered, as it must travel only along the bubble's trajectory, like a train on tracks. The energy fields required for the Alcubierre warp drive are primarily needed to create the space-time warp, but not to accelerate the spacecraft and to create these energy fields would require a significant amount of exotic matter elements such as tachyons. . Another recently discovered problem is that the mass accumulated along the path of the warp bubble would accumulate and shoot out at hyperspeeds when the ship comes to rest (similar to a shock wave) and could destroy any physical object located directly in front of the ship.
6. Conclusion
Warp Drive technology is decades or even centuries away from full development and coming into use, but it is not something that would likely emerge in our lifetime. The development of energy technologies, the investigation of subatomic particles, the dynamics of superluminal space and many other advanced focuses need to be strengthened before starting their research. Although it is in its early stages now, just thinking about it makes it mind-boggling to think about interstellar travel. This could give the human race its stamp on a galactic scale and could possibly introduce us to a new planet or an entire new alien civilization (good or bad is another matter). With the Alcubierre fold, the nearest star, Proxima Centauri, which is 4.2 light years away, can be reached in just 2 weeks. These numbers should certainly encourage scientists to work on the warp drive project.
Fig. 9: Image showing the Enterprise Starship concept intended for the Warp Drive application