Future space travel

Previously we discussed a few of the past technologies, our limitations in regards to space travel and prominent idea/theories that are being developed and tested right now. We have already discussed the Alcubierre Drive and Em Drive as those concepts are the most popular, but they are not the only the ideas that have been tested and developed. There is the Ion Drive or Ion thruster/ion propulsion, Quantum Entanglement, Wormholes and other theoretical space travel concepts that could be the future of interstellar travel.

The Ion Drive is a form of electric propulsion used for spacecraft propulsion which creates thrust by accelerating Ions. They are classified by the way they accelerating ions by using either electrostatic or electromagnetic force. The ion propulsion system is very promising because of its efficient use of fuel and electrical power enable modern spacecraft to travel farther, faster, and cheaper than any other propulsion technology currently available. Ion thrusters expel ions to create thrust and provide higher spacecraft speed than any other rocket currently available. Modern Ion thrusters use inert gases for propellant and the majority of them use xenon. In an ion thruster, ions are accelerated by electrostatic forces. The electric fields used for acceleration are generated by electrodes positioned at the downstream end of the thruster. Each set of electrodes, called ion optics or grids, contains thousands of coaxial apertures. Each set of apertures acts as a lens that electrically focuses ions through the optics. The way Nasa’s ion thrusters work is by using a two electrode system. An upstream electrode called the screen grid which is charged highly positive and the highly negative charged downstream electrode called the acceleration grid. Due to the fact that the ions are generated in a region of high positive and the acceleration grid being the high negative the ions are attracted towards and are focused out of the discharge chamber creating thousands of ions jets. The thrust force is created between the upstream ions and the accelerator grid. The difference between a chemical rockets top speed and an ion drives top speed is that the chemical rocket’s top speed is limited by the thermal capacity of the rocket nozzle. While the ion thruster's top speed is limited by the voltage that is applied to the ion optics (which is theoretically unlimited)
 

An ion propulsion system consists of five main parts. The power source, power processing unit, propellant management system, control computer and the ion thruster. While the power source for ion propulsion system can be powered by an sort of electrical power, the ones used most are solar and nuclear. A solar propulsion system uses sunlight and solar power cells for power generation, while a nuclear system uses a nuclear heat source for power generation. Ion thrusters are capable of propelling a spacecraft up to 90,000 meters per second. The only trade off being low output thrust. In order for the spacecraft reach its top speed, it has to stay operated for a very long time. What also makes the ion drive promising is that it is extremely fuel efficient when compared to modern spacecraft fuel. Making it perfect for deep space travel. ​​

Continuing on from the last weeks theme of unorthodox methods of space travel, wormholes are another proposed method of reaching distant galaxies in short intervals of time. Wormholes are essentially theoretical tunnels in the fabric of space that connect two points in space. it is analogous to to folding a piece of paper in half and poking a hole through it. In doing such, you have opened a “portal” from one side of the paper to the other side without having to travel a great distance. Wormholes work essentially the same way. theoretically, we can bend space (just like the paper) so that two points in the universe come much closer together. unlike the EM drive that was previously mentioned, the wormhole theory does not violate einstein's law of general relativity. While wormholes seem like a good solution to the issues of interstellar space travel, unfortunately it doesn’t seem like we will be travelling in them any time soon.

Wormholes (which are still theoretical by the way) are thought to be incredibly unstable. The wormhole would collapse the instant any object would try to go through it. the Wormhole theory also shares issue with the alcubierre (warp) drive, and that is negative energy. Just like the warp drive, a substance called negative energy is required in order for this theory to work. The problem is, negative energy is a theoretical substance itself and many scientists doubt its existence. Without negative energy, the wormhole will not be able to stabilize and we would not be able to send anything or anyone through it. Another issue with (or solution depending on your point of view) is that travelling through a wormhole may cause you to essentially age slower than everyone else. Suppose your journey in the wormhole lasted a few days. That short journey for you would last years for observers on earth. This allows the people travelling in the wormhole to age incredibly slow. It's essentially like travelling back into the future.

The Future: Alcubierre Drive

The most common and talked about concepts are the Alcubierre Drive proposed by Theoretical Physicist Miguel Alcubierre and the EM Drive proposed by aerospace engineer Roger Shawyer. These aren’t the only ways we can travel through the galaxies. There is also quantum entanglement, Wormholes, Ion drive, along with the use of tachyons and many other ways to travel through space. The Alcubierre drive is possibly the fastest way to travel to other planets and galaxies because you technically don’t travel through space at all. It is a warp drive that can expand and contract space relative to itself in order to travel throughout space, to be exact, it expands the space behind it, and contracts the space in front of it.

 The expansion of space behind is pushing the craft forward and the contraction in front is bringing it closer to its destination. It does this all whilst (technically) travelling faster than the speed of light. What this allows us to do is travel to places like Alpha Centauri, the closest star system to earth, in a matter of two weeks. If it could take us to Alpha Centauri in two weeks imagine what we could find in one year, two years, three years and so on. Technically, we can’t travel THROUGH space faster than light. What the Alcubierre drive does is it bends space. Space is dynamic; there is no limit to how fast we can expand or contract space. So it is technically faster than light travel without violating the laws of relativity because you aren’t technically moving, the space around you is. It seems like there is only positives about the warp drive, but with something positive there is almost always a negative. Some negatives to the drive is that we need a lot negative energy, which is theoretical in itself.

How could we get a lot of negative energy when we can't even get 1 gram? Also it is said that using the warp drive can possibly obliterate everything in its path. For example, after traveling in the warp bubble and arriving close to your destination, the warp bubble you are in will begin to slow down. When it slows down it releases an energetic outburst containing all the matter it picked up whilst in transit. On top of that, we don’t know if people could actually survive in these warp bubbles. So the chance of obliterating entire star systems and killing the entire crew is something to take into consideration. The Alcubierre drive seems like a good solution to our “faster than light problem” but it is based entirely on theory and seems quite unreasonable in our day.

 The warp drive, one of Star Trek’s hallmark inventions, could someday become science instead of science fiction.

I’m not buying it at all, and for good reason. Let’s take a look at why. First off, Einstein’s relativity tells you that nothing physical — matter, light, or energy in any form — can move faster-than-light. All experiments and plausible physical theories have verified that to be 100% true. So if you want to traverse vast distances, what you’d have to do is bend spacetime severely enough to let you either exit it at one point and re-enter at another (left) or collapse the space in front of you so you can move forward more quickly (right).

The exit-and-re-enter space is known as a wormhole, and it’s what Stargate uses. The collapse-space-in-front-of-you is the idea of Warp Drive, and that’s the famous form of transport used in the Star Trek incarnations. I haven’t seen it yet, but I’m sure this is going to play a role in the new Star Trek movie.

Not only do we have no experimental or observational evidence for both of these, we also believe the both scenarios are physically impossible in principle. Wormholes can exist, at least in theory, just by having an arbitrarily strong gravitational field at two points in space that wind up connecting, and they would cause space to go from looking like a flat grid to looking like this:

To travel through it, all you’d have to do is pass through that bridge area. The insurmountable problem? The gravitational fields required to make such a bridge within our Universe are so strong that they would tear individual atoms apart! As there’s no such thing in the Universe as something that can shield the gravitational force, this idea is doomed.

Now, what about warp drive?

Again, all you need to do to “foreshorten” space in front of you and lengthen it behind you is to take that flat grid of space and make it look like this:
 

Which doesn’t look too hard, at a first glance. There are a few major fundamental problems with this idea, though, which does, in fact, make it physically impossible. First off, it requires a vast amount of negative energy, which doesn’t exist in this Universe. The only way we’ve ever even conceived of negative energy is to take something of enormously positive energy and then measure a small, negative change relative to that big, positive number. And second, if you actually want to move matter at this speed, you need to plunk it down at the speed you want it to move at. This is a catch-22, as it means that you need to be moving at warp speed already if you want to move at warp speed. There are other problems associated with this that may or may not be insurmountable, such as getting out of warp drive once you’ve gotten into it, whether the gravitational fields will crush you, and whether there’s enough energy in the Universe to make this happen. But these two problems I’ve identified above ensure that this will remain in the realm of science fiction for a long, long time. And fiction is fine, but don’t try to pass it off as reality.

Interstellar Propulsion Systems

Warp Speed: What Is It And Will It Ever Be Possible?

January 28, 2017 by Russell Adam

The deciding factor in my preference of Star Trek over Star Wars has always been the technology. My girlfriend laughs when I say that ST is better than SW because the technology is real, or at least based on real concepts whereas SW is, for the most part, fictional. She then reminds me that a Ferengi gets turned on when you massage his ears and Q is a god.

In my defense, I still think I am actually right in this. Although many of the technologies used in Star Trek are often under-explained and glossed over, science advisers were brought in on each incarnation of the show to give advice on the realms of possibility. People like André Bormanis who worked on a few different seasons were often called on to ‘science-check’ the scripts and the special effects.


One of the most important technologies that Federation ships are equipped with is the warp engine. This engine, fueled by Dilithium crystals, allows spaceships to travel at phenomenal speeds and visit worlds that are many light-years from Earth. The speed is FTL, or Faster Than Light, and there are theories behind whether or not it is achievable. Einstein said no, as nothing with mass can travel faster than the speed of light. My understanding of Star Trek warp speed is that it follows the Alcubierre theory on FTL travel, where an object inside a bubble that is moving at the speed of light is not actually moving. If the space-time is collapsed in front of the bubble, then the bubble, including the ship, passes through quicker than the speed of light. This makes sense to me as the often talk of a warp field around the ship when the ship is travelling at this speed.


I don’t think Einstein and Alcubierre ever met, because I think they would have had a rather big disagreement. In Einstein’s celebrated work, the Special Theory of Relativity, he fervently implied that nothing can travel faster than the speed of light. If we are ever going to get to another world outside of our own solar system, we are going to need Einstein to be wrong, for once. Alcubierre was a Mexican physicist who stated that fabric of space-time could be stretched and moved, allowing an object to pass through at faster than the speed of light. For Star Trek to happen in real life, we need this dude to be correct.

Alcubierre Theory:

To put it simply, this method of space travel involves stretching the fabric of space-time in a wave which would (in theory) cause the space ahead of an object to contract while the space behind it would expand. An object inside this wave (i.e. a spaceship) would then be able to ride this region, known as a “warp bubble” of flat space. This is what is known as the “Alcubierre Metric.” Interpreted in the context of General Relativity, the metric allows a warp bubble to appear in a previously flat region of space-time and move away, effectively at speeds that exceed the speed of light. The interior of the bubble is the inertial reference frame for any object inhabiting it.

Einstein might have disagreed with the theory, but there is a way that they can both be right. Considering that the region of space is moving, and not the ship itself, normal conventions would not apply. Time dilation doesn’t happen and as such, no breaks in the rulebook of space-time and the laws of relativity would have been made. Everyone would be happy campers.

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The Future: EM Drive

Another controversial topic amongst the technology community is the infamous EmDrive. This technology uses an unconventional method of thrust to move the spacecraft. In fact, this type of engine would use absolutely zero propellant! It creates thrust by bouncing microwaves at a specific calculated frequency inside of a resonant chamber in order to produce thrust. The controversy comes from the idea that this should not be possible whatsoever. The EMDrive (or resonant cavity thruster) supposedly violates the law of conservation of momentum. According to our current understanding of physics, the EMdrive should not have more momentum than initially put in, but it does. The thrust created from the engine is very small, but is still measurable. Through the tests conducted by several physicists and NASA’s EagleWorks lab, a force of about 30-50 mN was recorded. This is only about 0.03-0.05 N, a very insignificant force. Another Chinese team has also attempted to create an EM drive and their thruster provides 720mN. Even though the progress may be slow, if we can get the EM drive to produce astounding results then we may be able to travel throughout the universe. Although there are other technologies being developed, the Alcubierre drive and the EM drive have the most potential in being our next solution to interstellar travel, despite all its controversy.

Faster Than Light Travel:– Fact or Fiction?