[Prosthetic Conscience]

The phrase “lightspeed ahead” will need to stay just that for now. While scientists continue to study ways to create faster, more efficient space travel within our solar system and beyond, a recent project to test NASA’s EmDrive determined that this thruster technology remains on the cusp of being a viable solution.

The EmDrive, an experimental space engine concept, is a hollow cone constructed from copper or other material that is placed in a frame. In theory, as natural microwaves bounce around inside the cone, they create a thrust to propel a rocket without the need to carry fuel. There just happens to be one major flaw with this idea: it defies current laws of physics.

A team of Technische Universität Dresden physicists in Germany decided to conduct its own test of the EmDrive, the SpaceDrive Project. The researchers presented their independent findings at the 2018 Aeronautics and Astronautics Association of France’s Space Propulsion conference. Their results showed that outside factors contributed greatly to the engine’s thrust.

Led by Martin Tajmar, the TU Dresden team built a replica of the EmDrive, or one that was as close as they could get based on leaked information. They then put their engine into a vacuum chamber and bombarded it with microwaves. They discovered that although the EmDrive experienced thrust, it was unlikely that it was produced by the engine since there was thrust regardless of the engine’s direction. This suggests that the Earth’s magnetism could be the point of the thrust’s origination. The report’s conclusion stated:

“First measurement campaigns were carried out with both thruster models reaching thrust/thrust-to-power levels comparable to claimed values. However, we found that, e.g., magnetic interaction from twisted-pair cables and amplifiers with the Earth’s magnetic field can be a significant error source for the EmDrive. We continue to improve our measurement setup and thruster developments in order to finally assess if any of these concepts is viable and if it can be scaled up.”

This suggests that previous tests that recorded a thrust may have been just a glitch. But, if other testing was accurate, than it could indicate that the laws of physics were defied in those small amounts of thrust.

In addition to testing the EmDrive, the team completed research on the Mach Effect Thruster, another improbable concept based on the idea that fluctuations generated in a piezo-crystal stack will create non-zero time-averaged thrust.

Using their vacuum chamber once again, the TU Dresden team noted more promising results, but not enough to prove it a valid idea. Although the thrust produced was 100 times more than was predicted, it stopped when the thrusters were off and did not work when the engine was put into reverse. The testing also suggested that as with the EmDrive, outside factors likely generated the thrust.

While these concepts still seem improbable as space travel solutions, the German team recommends further testing to truly verify or disregard their potential capabilities.

https://www.engineering.com/DesignerEdg ... ravel.aspx

Damn. Another idea for reaching the stars bites the dust. Earlier thread on this: viewtopic.php?t=166162

[Steve_American]

I hope this is close enough to be on topic.

I confirmed this with a Physics Prof. some years ago.

When scientists tell you "You can't go faster than light," they are simplifying and confusing you.
What they really mean is "You can never measure a velocity faster than light."
Physicists also say that using a measurement in one frame of reference and another measurement from a different frame of reference in the same calculation is an "Improper Calculation". This is their code word for "Don't do that".
I contend that it is NOT IMPROPER when we are talking about the travels of an Astronaut. From their point of view the following calculation makes perfect sense.

Measure the distance to a distant start from earth [at rest?], then measure the time it takes to get there on the spaceship, then do a normal calculation to get the average speed during the trip.
Distance traveled / time it takes == average speed.

Everyone knows that near the speed of light time slows down.
Not everyone knows about the other things that happen near the speed of light. They are ---
1] The mass of the particle or spaceship rises to infinity as the limit if you ever reach the speed of light.
2] All the lengths in the direction of the velocity are reduced toward zero as the limit if you ever reach the speed of light.

The reason you get a speed faster than light when you do the above calculation is that the distance you need to travel during the trip is reduced as you go faster and faster near the speed of light. However, how much less depends on your actual speed so it is hard for those left at home to visualize. I think it is better to just do the "Improper calculation", but understand what you have done.

Someone watching the spaceship from the Solar System will see it take an amount of time greater than the distance in light years, but the Astronauts will see it take less time, because for them time slowed down.

So, if you can get going near light speed and not die*, you can reach the starts, but you can't return home to see your family because their time did not slow down, and yours did.

.*. The problem therefore is not the speed of light --- the problems are --- how to go that fast, how to have enough fuel, and how to not be killed by cosmic rays and grains of sand that you collide with at 90+% of light speed during the trip. The OP was addressing "how to go that fast."
.

[Steve_American]

Not one like or reply.
Can any one of you understand what I wrote?

[Prosthetic Conscience]

Yes, I understood it, but didn't think it needed a reply. I'd say that if one is thinking about what a 'no reaction mass' rocket would mean, it's more the "how to have enough fuel" aspect. If you have to carry your future reaction mass with you (to both accelerate and decelerate), then you need more and more energy to accelerate it before using it, and exponentially more reaction mass to do the acceleration etc. Getting anywhere near light speed is a huge problem. But if you're counting on relativistic effects to keep you alive long enough to get to the end, you also get problems with the spaceship (and your) mass increasing near the speed of light - again making it harder to accelerate.

If you can dispense with reaction mass, you might be able to use an external energy source, and just have to accelerate the 'true' ship, rather than its fuel.