Exciting for sure.  However, you cannot get something for nothing.  There must be a power source, which in this case is solar energy.  OK, fine.  This means that it is not "zero fuel", as you are restricted to being near a star for power. 

You still need to produce propulsion, which always involves an accelerating force, so something has to be accelerated in one direction to produce motion in the opposite direction. 

The developers here claim that they are using some mysterious "quantum" force to produce the acceleration.  They are very vague about the technology and there are no details about how it works.  OK, I get they they have a patent pending and don't want to reveal their secrets.

I have always suspected that there is a way to distort space in order to produce motion without accelerating a mass, probably using electromagnetic forces to "bend" the space.  Perhaps that is how this works.  Boy, I hope so.  If so, it's a game changer.  You could upscale this thing to use a fusion, or even fission, reactor and pump a lot of amps into it to produce significant acceleration and thus truly be able to travel to other planets routinely, and maybe even to the stars if you can get to at least 50% of the speed of light.

I remain skeptical, but we'll know if it works soon, hopefully.

Dave

Edited November 8, 20232 yr by dave2013

8 hours ago, dave2013 said:

 They are very vague about the technology and there are no details about how it works.  OK, 

 

Quantized Inertia.

McCulloch's presentation is on previous page.

12 hours ago, dave2013 said:

have always suspected that there is a way to distort space in order to produce motion without accelerating a mass, probably using electromagnetic forces to "bend" the space.  Perhaps that is how this works.  

 

Well yes, we are all aware of the Alcubierre metric. But no, this is nothing to do with bending space which would require negative energy that we have no idea exists or not.

I'm still waiting for confirmation that it did launch on Transporter 8. The counter on the website has reset to zero. 

Video, previous page.

 

And this one...

 

 

Edited November 8, 20232 yr by martin-w

6 hours ago, martin-w said:

Well yes, we are all aware of the Alcubierre metric.

The existence of this Unruh radiation is not proven and is only a theory.

Interestingly, this whole "quantized inertia" thermodynamic accelerating effect that he describes could also be explained by a distortion of space.

Einstein showed that space is an actual "thing" and that it can be "bent", and that it is this bent space that causes objects to accelerate.  Gravity is simply a distortion of space and not a "force".  I see scientists come up with complicated theories to explain things that could also be explained by spacial effects, or call it the "ether". 

I don't claim to understand all the advanced math with this stuff, as it's been over 20 years since I used Calculus, but I do believe that if scientists can find a way to bend space to produce acceleration without accelerating a mass then it is this type of propulsion that will enable mankind to travel to the stars.

Dave

 

1 hour ago, dave2013 said:

Interestingly, this whole "quantized inertia" thermodynamic accelerating effect that he describes could also be explained by a distortion of space.

 

I don't believe so, not enough energy. Distorting spacetime  sufficient for some kind of drive, requires negative energy or mass, and a LOT of it. Hence the Alcubierre drive. 

He has an explanation that relates to waves and boundaries. IF there's something to this, which there probably isn't, it's not likely to be related to any warping of spacetime. 

Peter is the scientist around here, that could give a more educated explanation of how this device is likely to work, if indeed it does.

You are both correct. Unruh radiation is similar to Hawking radiation near black holes, but there is not experimental proof for it. Conventional theories predict that it will be tiny. You need 10^20 g of acceleration (100 billion billion times Earth's gravity) to get a thermal radiation of just 1 Kelvin (about a third of the cosmic microwave background radiation). I didn't go into the details of the quantum drive, it is based on highly speculative assumptions. If conventional theories are correct, you wouldn't need an Unruh shield.

And yes, one may in principle be able to bend space and time, but the amount and type of energy required is beyond anything we can even imagine to produce. Vacuum energy is not very well understood, and there may be logical inconsistencies (like time travel) be associated with it. I am not holding my breath for a warp drive trip.

Peter

13 hours ago, qqwertz said:

and there may be logical inconsistencies (like time travel) be associated with it.

 

Only to the future though, not the past. So no causality issues.

For mass required Broeck got it down to the mass of the sun.

There are some solutions that don't require negative energy but they result in velocities slower than light speed.

Edited November 9, 20232 yr by martin-w

1 hour ago, martin-w said:

 

Only to the future though, not the past. So no causality issues.

For mass required Broeck got it down to the mass of the sun.

There are some solutions that don't require negative energy but they result in velocities slower than light speed.

Like a warp drive, wormholes also require negative energy to be created. And they do create causality problems:

And yes, as long as you stay under the speed of light, a warp drive doesn't need exotic forms of energy. But, seriously, who ever wants to drive under the speed limit 🤠

52 minutes ago, qqwertz said:

And they do create causality problems:

 

 I'll look at your video. 

In your video Brian Greene concludes that time travel backwards "might" be possible. 

 

Quote

 But, seriously, who ever wants to drive under the speed limit 

 

Lentz solution was for no negative energy and faster than light. 

Are you talking about closed time-like curves? And despite no acceleration within the bubble, the bubble still traveling FTL in the flat space around it, thus still causality violations?  

 

 

Edited November 9, 20232 yr by martin-w

1 hour ago, martin-w said:

 

1) Lentz solution was for no negative energy and faster than light. 

2) Are you talking about closed time-like curves? And despite no acceleration within the bubble, the bubble still traveling FTL in the flat space around it, thus still causality violations?  

 

 

1) Interesting, I wasn't aware of this paper. I'll look into it and get back to you. Full disclosure: I have published on warp drives, so I know how they work, but I wouldn't consider myself an expert in the field and I don't follow the literature on it.

2) Ah, we're getting into the finer philosophical points. Yes, time travel is logically possible if either (i) everything that happens is predetermined, according to some kind of master plan, or (ii) history repeats itself. That's really all closed time-like curves are, and you can think of this as a particularly dull form of a master plan. 

I personally don't believe in either of these possibilities, but I am a firm believer in causality. That's why I do not believe in the possibility of a warp drive. Going faster than the speed of light would mean that, in some reference frame, you are going backwards in time. Now, space-time curvature considerably complicates this argument, and I never tried to fully elaborate on this. Plus, going backwards in time doesn't necessarily lead to a contradiction. For instance, anti-particles go backwards in time, but the effects of their motion are in full agreement with causality. So I can't prove a contradiction, but you will not catch me applying for a job at Ivo 🙂

1 hour ago, qqwertz said:

Plus, going backwards in time doesn't necessarily lead to a contradiction. For instance, anti-particles go backwards in time

 

Do they though. 

 

Do anti particles go back in time?

 

Quote

No, antimatter does not move backwards in time. However, normal matter moving forward in time can be reinterpreted as antimatter with negative energy moving backwards in time, and vice versa.

 

It's a mathematical notion only isn't it? 

 

Edited November 9, 20232 yr by martin-w

38 minutes ago, martin-w said:

Do anti particles go back in time?

It's complicated. Imagine you have a tray fully packed with marbles, so that none can move. If you take out one marble, they can start moving by filling the hole that is left behind. Instead of describing how all the marbles on the the tray move, you can instead consider how the hole moves. If you push a marble to the right, the hole will move to the left. The hole behaves like a marble that moves in the wrong direction. And, since the marbles obey the laws of nature (Newton's 2nd law), the hole also obeys a law of motion, which looks exactly like that of a marble moving backwards in time.

Now look at atoms. Electrons in an atom obey the Pauli principle, they can't be in the same state and therefore fill up energy levels. The number of electrons is fixed for each chemical element, so the ground state of an atom looks like a bunch of electrons sitting in energy levels (think of a ladder), filling it from the bottom upwards. You can kick electrons in an atom around using electric fields and light. If you do, an electron will leave a hole on the ladder step it previously occupied. That hole will again move like an electron, but with opposite charge and backwards in time. 

For atoms and trays, this hole theory is just a convenience, not a fundamental property. However, if you consider relativistic electrons with mass M, they can have either positive energy that is larger than (or equal to) their rest energy M c^2, or they can have negative energy less than -M c^2. The latter poses a problem since you could generate an infinite amount of energy by letting electrons fall down the infinite energy ladder, so-to-speak.

Dirac proposed using hole theory to resolve that problem. In the ground state of the universe, all negative energy states are occupied. You can remove electrons from these states, thus creating a hole that moves backwards in time. Such a hole is called positron and corresponds to the anti-particle of an electron. They move backwards in time, but only since they are kind of a hole in the ground state, and their net effect is to preserve causality. 

 

I looked a bit more into the positive-energy solution by Lentz. It has been criticized in https://journals.aps.org/prd/abstract/10.1103/PhysRevD.105.064038. This paper is very technical but asserts that a warp drive would generally be in violation of some fundamental principles in general relativity. This is a serious rebuttal of the Lentz's solution (which, however, is really interesting and good work, despite being on shaky ground). Matt Visser is a leading expert on warp drives and has been working on it for a quarter of a century or so.

By the way, it is even difficult to precisely define what energy is. The generally accepted way is associated with a symmetry (a so-called time-like Killing vector). This symmetry exists in flat space, but not always in curved space. Without a symmetry, it is even difficult to define what positive and negative energy is, so the entire discussion about energy violation and negative energy in curved space is still work in progress. We have a fairly good, but not yet complete, understanding of what happens. So, I wouldn't rule out a warp drive completely, but I would be surprised if someone could build one. Well, chances are I won't be around anymore to witness this on April 5, 2063 🙂

Well done Peter. I'm going to give you 9/10 for that one.

And two cat points.

😸X2

I actually do not believe that "time" exists.  Time is just a construct that sentient beings like ourselves have created to reference events, IE this happened before or after that.

It's sort of like the zero - it is actually nothing but is useful in math.

There is only space, matter, and even the mysterious electromagnetic "fields" and "waves" could possibly be explained by spacial waves/fields.  No "space-time", just "space".  This eliminates and solves the argument about whether photons are waves, particles or both.  It's all actually spacial waves created by moving masses.

I know, it's a bit out there, but worth investigating I believe.

Dave

9 minutes ago, dave2013 said:

I actually do not believe that "time" exists.  Time is just a construct that sentient beings like ourselves have created to reference events, IE this happened before or after that.

It's sort of like the zero - it is actually nothing but is useful in math.

There is only space, matter, and even the mysterious electromagnetic "fields" and "waves" could possibly be explained by spacial waves/fields.  No "space-time", just "space".  This eliminates and solves the argument about whether photons are waves, particles or both.  It's all actually spacial waves created by moving masses.

I know, it's a bit out there, but worth investigating I believe.

Dave

 

Time is a measurable, observable phenomenon though. There's no real doubt that it exists. 

Explained by entropy perhaps?

There is the concept of block time or the block universe, whereby all time, past present and future exists in one four dimensional block. In which case the passage of time would be illusory.