Feeder Train and Alcubierre Drive
Tauhid Nur Azhar
This evening, on the feeder train (KCIC) connecting Padalarang Station with the main station in Bandung, a young couple in front of me was having a heated argument. The whispered insults they exchanged, perhaps out of embarrassment if other passengers on the crowded green train heard them, made them seem like a pair of cobras spitting venom at each other.
The woman sitting next to me and I seemed to be ignored. The venomous whispers, accompanied by intense eye-rolling, continued for the 19-minute journey. But when I accidentally overheard the root cause of their argument, which was as intense as the conflict between Ukraine and Russia, the woman next to me and I could barely hold back our laughter.
They were arguing fiercely over buying return tickets to Jakarta, and also about Whoosh. Essentially, the wife was explaining that the available tickets on the app were only from two departure stations: Tegalluar and Padalarang. Her husband retorted sharply, “There should be a Bandung station, since we’re getting off in Bandung.”
His wife wouldn’t accept it and replied, “Why don’t you just make your own fast train from Bandung to Halim? The app doesn’t have it, so why insist?” Her husband looked shocked, “Whoosh stands for KCJB, the Jakarta-Bandung fast train, so it’s impossible not to have a departure station from Bandung, think about it…”
He continued, still highly emotional, “And if we buy tickets from Padalarang to Halim, how are we going to get to Padalarang? It’s far. Women really can’t understand maps.” That was his husband’s remark, clearly annoyed, as he turned his face towards the window.
The woman next to me and I exchanged glances, thinking, “We’re taking the feeder from Padalarang too.” But until we arrived at Bandung Station, neither of us informed them that the Padalarang-Halim ticket could be used from Bandung Station with free feeder service.
We were both confused about how to tell them, as they should have known if they weren’t so emotional. Especially since they were also on the feeder train at that moment. Due to their intense emotions, the couple took different paths at the end of the escalator. The husband turned right towards the station hall, and the wife struggled to see her husband turn left towards Kebon Kawung. I was confused.
Suddenly, as the husband approached platform 5, where the KA Ciremai train to Bandung-Semarang Tawang was boarding, he looked back and realized his wife wasn’t there. Similarly, the wife, who was about to take the escalator down to the Kebon Kawung exit, looked back and realized her husband wasn’t there.
They both turned around and started running. I was so shocked I didn’t have time to activate my phone camera, even though a slow-motion video of that scene would have been epic, especially with Bollywood-style music. They ran towards each other, and it ended in an epic embrace.
This reminded me of a similar incident involving Mas Bambang Iman Santoso, a doctoral student at Gajah Mada, and his wife, Teh Rina Papatong Natarina, a doctoral student at Gajah Ganesha.
I don’t know if it’s the nature of the two elephants or what, but this couple often had heated debates in low tones to avoid being overheard. But the emotional outbursts were clear signals of love between the elephants.
The 19-minute journey from Padalarang Station to Bandung Station also disrupted my plan to daydream throughout the trip. After returning from the Rekind Kalibata office, I was ready to immerse myself in thoughts about the amazing implementation of scientific advancements into cutting-edge technology.
My daydream on the GoJek was interrupted by the driver’s friendly chat about the weather in the capital, while my daydream on the fast train was cut short because I fell asleep. So, I continued my daydream while walking through the quiet streets of Pasir Kaliki.
My daydreams are usually science fiction, inspired by the history of science that I had been studying since morning and my friend Janu Dewandaru’s enthusiasm for various technologies in the movie Star Trek.
If my daydream were to be filmed, the synopsis would be something like this: In the year 2100, Indonesia makes history. Through a technology consortium led by PT Dirgantara Indonesia, along with national strategic industries and BRIN, the first intergalactic spacecraft based on Alcubierre Drive technology is successfully launched.
The name of this spacecraft, “Nusantara Lintas Galaksi,” becomes a symbol of the nation’s technological revival, surpassing the dominance of the United States and Russia, which rely on WARP Drive technology.
“We bring the spirit of Bhineka Tunggal Ika to the stars,” said the CEO of PT Dirgantara Indonesia at the historic launch at Biak Space Base. Alcubierre Drive technology allows Nusantara Lintas Galaksi to exceed the speed of light without violating the laws of physics.
How is this possible? Let’s understand the technology behind it.
Alcubierre Drive, first proposed by Miguel Alcubierre in 1994, is a theoretical solution for traveling faster than light. In this concept, the spacecraft creates a space-time bubble that contracts in front and expands behind, allowing interstellar travel without violating Einstein’s relativity.
This technology is based on Einstein’s field equations: Gμν + Λgμν = (8πG/c⁴) Tμν This equation explains how energy and matter influence space-time, and with the distribution of exotic energy (negative energy), space-time can be distorted so that the spacecraft remains stationary relative to its bubble.
The space-time metric used for the warp bubble is: ds² = -c²dt² + [dx — vₛ(t) f(rₛ) dt]² + dy² + dz² where: vₛ(t): speed of the warp bubble f(rₛ): negative energy distribution function rₛ = √((x — xₛ(t))² + y² + z²) The spacecraft does not move through space; instead, space itself carries the spacecraft.
To create a warp bubble, exotic energy with negative energy density is required. The distribution of negative energy is calculated by the equation: T₀₀ = -(κ / 8π) * [∂²f(rₛ)/∂rₛ² + (2/rₛ) * ∂f(rₛ)/∂rₛ] where: κ is the gravitational constant. The discovery of the Casimir effect by theoretical physicists has been a major breakthrough. Even though the United States and Russia at that time (2100) used WARP technology based on quantum string theory, Indonesia chose Alcubierre Drive due to its more stable and energy-efficient nature on a large scale. This was especially true after researchers found that the combination of Casimir energy and high-temperature superconductors allows for more efficient space-time distortion.
The Casimir effect itself is a quantum phenomenon first explained by physicist Hendrik Casimir in 1948. This effect occurs due to quantum vacuum fluctuations, which are virtual particles that appear and disappear in empty space. This effect creates an attractive force between two parallel metal plates placed very close together in a vacuum.
In the context of Alcubierre Drive, the Casimir effect is considered one of the candidates for a source of negative energy required to create space-time distortion.
When two parallel metal plates are placed very close together, the field fluctuations between the plates are limited compared to those outside the plates. This creates a pressure difference that results in an attractive force.
Casimir Force Formula F/A = — (π² ħ c) / (240 a⁴) where: F: Casimir force (Newton) A: surface area of the plates (m²) ħ: reduced Planck constant ≈ 1.05 × 10⁻³⁴ Js c: speed of light ≈ 3 × ¹⁰⁸ m/s a: distance between the plates (meters) The total energy due to the Casimir effect can be calculated by: E = — (π² ħ c A) / (720 a³) where: E: Casimir energy (Joule) A: area of the plates (m²) a: distance between the plates (meters) Other constants are the same as above. The Casimir effect is important in generating the negative energy required to create space-time distortion. In the Alcubierre Drive scenario, the negative energy from this effect can be used to form a warp bubble, allowing interstellar travel without violating Einstein’s theory of relativity.
Recent research shows that nano-technology or superconductors can be used to increase the intensity of the Casimir effect, making this negative energy easier to utilize.
It’s not just Alcubierre Drive that is a hypothesis related to intergalactic travel. In 2021, Eric Lentz, a theoretical physicist, proposed a new design for warp geometry that allows for faster-than-light travel without requiring exotic energy.
This approach provides a practical alternative to the Alcubierre Drive concept, which heavily relies on negative energy, a source of power that is not yet known how to create in large quantities.
Lentz uses Einstein’s general theory of relativity to formulate a warp solution that only uses positive energy from conventional mass and energy distributions. This concept is based on the principle that space-time can be designed to create a warp bubble that moves at superluminal speeds without violating local physical laws.
Lentz’s warp geometry uses hyperboloid symmetry, different from Alcubierre’s spherical symmetry. This symmetry allows for a positive energy distribution. In the universal framework, the warp bubble moves faster than light. However, there is no violation of local relativity because the spacecraft remains within the space-time bubble without exceeding the speed of light in its local environment. Theoretically, the energy used in this warp geometry comes from ordinary matter and energy, eliminating the need for exotic or negative energy.
Lentz’s warp solution is based on: Gμν = (8πG/c⁴) Tμν In this model, the energy-momentum tensor (Tμν) only contains positive energy, so it does not require a negative energy distribution.
The space-time metric for the warp bubble is: ds² = -c² dt² + [dx — vₑ(t) f(rₑ) dt]² + dy² + dz² where: vₑ(t): speed of the warp bubble f(rₑ): positive energy distribution function rₑ = √((x — xₑ(t))² + y² + z²): radial distance from the center of the bubble The positive energy distribution in this solution is designed to satisfy: T₀₀ > 0 This means the energy used comes only from conventional matter and energy, making it more realistic compared to the Alcubierre Drive.
At the end of this writing, I apologize profusely because, due to the limitations of writing physics and mathematics notations in WA chat, the formulas I tried to elaborate above have been simplified and only partially displayed, as there are no symbols in the WA keyboard that can be used. So, there is a high potential for errors and mistakes.
Please consider it as mere musings, after all, it’s just a daydream on a GoJek riding through the streets.
But the message I want to convey is that, even though all of this is still just theory or hypothesis requiring much experimentation and proof, there is still a thin probability that it could become a reality.
Just like the hypotheses of Faraday, Volta, Edison, Tesla, and many other scientists like Fritz Haber and Carl Bosch, whose theories, accumulated over time and through various experiments, have been proven to become practical products that can be replicated, reproduced, and used according to their functions.
Who would have thought that Ibnu Firnaz’s leap experiment, or Abbas Ibnu Firnaz, near the Arus Jabal cliff in his hometown of Cordoba, would be followed by the Wright brothers’ experiments at Kitty Hawk almost 12 centuries later? And less than a century later, we can travel between continents in a relatively short time using wide-body jet aircraft that can fly at subsonic speeds.
Who would have imagined that James Watt’s steam engine experiment, followed by George Stephenson and Richard Trevithick, would result in transportation in Java just 38 years later (1867), marked by the completion of the railway line between Samarang and Tanggung Station. The station began construction in 1864 by the Nederlandsche Indische Spoorweg Maatchappij (NIS).
There are still many inventions born from the journey of research by scientists, often separated by time and methods of observation. But it seems there is a network of scenarios that can unite these breakthroughs, becoming innovations or discoveries that have a significant impact on the construction of civilization.
Finally, I wonder, what if the young couple arguing on the feeder train earlier had their incident not on a diesel-electric train between Padalarang and Bandung, but on an intergalactic spacecraft with Alcubierre Drive or Lentz’s Warp Geometry?
When one turns left and the other turns right, in a relatively short time, the warp bubble would take them to a star cluster in a different part of the universe, right? The wife could arrive at a planet in the Achernar star system in the constellation Eridanus, which is 139 light-years away and 11.4 times the size of the Sun. This star is of spectral class B6Vep, meaning it is a main-sequence star with a variable type BE.
Meanwhile, the husband could land on a planet in the Arcturus star system, also known as Arktouros, the guardian of the bear, located north of the celestial equator. Arcturus is 37 light-years away and 25 times the size of the Sun. It is classified as a giant star of class III and type K0.
The Bollywood-style running scene at Bandung Station earlier would be hard to replicate if the couple decided to elope to different constellations, even different galaxies. Imagine how far apart they would be; our Sun is about 35,000 light-years from the center of the Milky Way galaxy, let alone if they were in different galaxies. How many light-years would you need? 🙏🏾
References and Further Reading
Alcubierre Drive and Warp Geometry Alcubierre, M. (1994). The warp drive: hyper-fast travel within general relativity. Classical and Quantum Gravity, 11(5), L73-L77. https://doi.org/10.1088/0264-9381/11/5/001 Einstein, A. (1916). Die Grundlage der allgemeinen Relativitätstheorie. Annalen der Physik, 354(7), 769–822. https://doi.org/10.1002/andp.19163540702 Ford, L. H., & Roman, T. A. (1996). Quantum field theory constrains traversable wormhole geometries. Physical Review D, 53(10), 5496–5507. https://doi.org/10.1103/PhysRevD.53.5496 Lentz, E. W. (2021). Breaking the warp barrier: hyper-fast solitons in Einstein–Maxwell-plasma theory. Classical and Quantum Gravity, 38(7), 075015. https://doi.org/10.1088/1361-6382/abe692 Casimir Effect Casimir, H. B. G. (1948). On the attraction between two perfectly conducting plates. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, 51, 793–795. Bordag, M., Mohideen, U., & Mostepanenko, V. M. (2001). New developments in the Casimir effect. Physics Reports, 353(1–3), 1–205. https://doi.org/10.1016/S0370-1573(01)00015-1 General Relativity and Fundamental Physics Theory Misner, C. W., Thorne, K. S., & Wheeler, J. A. (1973). Gravitation. W. H. Freeman and Company. Wald, R. M. (1984). General Relativity. University of Chicago Press. Visser, M. (1995). Lorentzian Wormholes: From Einstein to Hawking. Springer.
