I've suggested (& published in 21 journal papers) a new theory called quantised inertia (or MiHsC) that assumes that inertia is caused by relativistic horizons damping quantum fields. It predicts galaxy rotation, cosmic acceleration & the emdrive without any dark stuff or adjustment. My Plymouth University webpage is here, I've written a book called Physics from the Edge and I'm on twitter as @memcculloch

Wednesday, 30 September 2020

Consider an Owl

I've just published what is possibly the most elegant paper I have ever written. I sent it to various journals who all turned their noses up at it (one sympathetic editor told me that reviewers were refusing to review it en masse) so thank you to Advances in Astrophysics for giving it a home. In it, I derive quantised inertia in eight lines from information theory, just by assuming that information is stored in Planck-length spaces.

Consider the diagram below. This represents, in one-dimension, an object (say, an owl) by the thicker vertical dashed line on the left. Initially the owl is just sitting there so it sees the cosmic horizon on its right, the right-most vertical dashed line. The owl has a lot of information about space. The Planck length is the smallest region of space in which information can be stored and in the diagram (not to scale!) Mr Owl can see 26 bits of space. Then imagine someone rudely moves him abruptly to the left. Suddenly information cannot catch up to him from far to the right and the horizon he sees moves closer - see the middle vertical line. Now the owl can only see nine bits of space.

This is a loss of information, and according to Landauer's principle, it also counts as a loss of entropy, just as deleting a computer memory would. This is a huge no-no from the point of view of thermodynamics - entropy must always go up. In the paper I show that if you calculate how much energy is released to Mr Owl in this case, it is exactly the amount of energy needed to produce, not just inertia, but specifically the form of inertia of quantised inertia, which models galaxy rotation without dark matter and predicts cosmic acceleration.

Now, of course, this example is only one-dimensional but I think it offers a new, simpler and deeper way to understand quantised inertia, and derive it. I hope that information theorists will pay attention. It is a sign that their subject is just about to conquer the rest of physics. Welcome to a new branch of physics. And the owl? Understandably, he's chosen a new branch to sit on. Higher up in the tree.


McCulloch, M.E., 2020. Quantised inertia and galaxy rotation from information theory. Adv. Astrophy., 5, 4. http://www.isaacpub.org/4/2050/5/4/11/2020/AdAp.html

Tuesday, 8 September 2020

The Ball and the Teapot

Imagine a ball in space. Strictly speaking in physics and especially in quantised inertia you can't start talking about it being stationary or not because it has to be moving relative to some other object, so let's say it's static relative to a nearby teapot, but far enough away that the attraction from the teapot is small.

Now put a horizon on one side of it. According to quantised inertia this will damp the Unruh waves from the direction of the horizon and so the ball will be pushed by the imbalance in the Unruh radiation field towards the horizon. Another way to think about the same thing, the informational way (see reference) is that the horizon deletes the knowledge the ball has about the cosmos beyond it. Landauer's principle says that every time you delete information, say, you erase 101011 to 000000, then entropy decreases. That cannot be allowed, so the second law of thermodynamics says that high-entropy heat energy must appear to compensate. So computers get warm when you erase data. I've calculated this energy for the deletion of space, and it turns out to be just enough to power the movement of the ball predicted by quantised inertia (see ref).

So the ball accelerates towards the horizon. Now, as pointed out by several people online or in emails, what happens if suddenly the horizon disappears so the ball gets back all its knowledge about the cosmos behind it? The problem is, it still has the kinetic energy it picked up from the loss of information. Does it lose the energy when it gets the information back? The answer is not necessarily "Yes", because although the second law of thermodynamics says that 101011->000000 must release energy, there is no such imperative for 000000->101011, since there is no drop in entropy.

Can we use this asymmetry, and repeat the process to generate energy? I think that is what is happening with the cycling photons (near and horizon, then far..etc) in the emdrive. However, this brings up many fascinating new questions to ponder. Where is the information 'stored' while the horizon is close, so the system can get it back when the horizon is gone? Can information or heat be swapped between reference frames? How does this relate to the black hole information paradox?

Getting philosophical for a moment it makes sense that our new ability to model worlds ourselves (simulations, games) is inspiring new models of the one we are in, including my recent attempt to express quantised inertia using information theory. Is it just the latest useful analogy? (Probably). Is the cosmos a self-evolved bit-system? Or are we in a deliberate simulation? I'm sure the theologists will spend many a happy hour discussing that!


McCulloch, M.E., 2020. Quantised inertia, and galaxy rotation, from information theory. AdAp (accepted). Summarised in my ANPA talk here (the relevant bit starts at 16:24)

Thursday, 3 September 2020

What I said to Wired

An article has just appeared in WIRED about Woodward's theory. The author Daniel Oberhaus emailed me a couple of weeks ago asking my opinion of Woodward's work and he quotes me in the article as saying "In my opinion there is no merit to Woodward's theory". See this link for the article. This quote is a 'slight' truncation of what I said :) See his questions in bold, and my answers below:

Wired: How would you sum up your feelings about Jim's theory in a sentence or two? Is he crazy or is there merit to his ideas?

In my opinion there is no merit to Woodward's theory. It shares the problem of most of modern physics that it is constrained to work within the framework of general relativity so the derivation is complex and contrived and contains many unlikely assumptions and even some arbitrarily added factors, and yet it is still orders of magnitude away from predicting the Mach effect thrust it was intended to predict! The Mach Effect experiments are interesting but we have to consider the possibility that they are vibrational artefacts.

Wired: There's clearly a lot of skepticism around Jim's Mach effect theories. If you count yourself a skeptic, what don't you buy about this theory?

There are many theoretical problems with it, see eg Rodal 2019 and in going through the derivations you see that a lot of arbitrary factors are added in. However, my main reason for disregarding it is that it does not work. It fails to predict even the lab observations it was designed to explain - its predictions of observed thrust have been shown to be a factor of one thousand times out (eg: Mahood, 1999). I note that in the papers written about it the data is rarely compared with the observations directly.

Wired: What would it take to convince you that it was correct, if anything?

To convince me it would need a simply-derived non-arbitrary formula that predicts all the Mach Effect thrust experiments and a demonstration that the thrust varies as expected given the parameters in the theory, to rule out artefacts. So pretty much the opposite of what has happened so far.

Wired: Jim's been claiming to have produced propellantless propulsion for years. Do you think these results are real, or just noise / measurement error?

I think the experimental results are more interesting than the theory, but there is a significant possibility with vibrating solid objects that artefacts can occur (as seen with the Dean drive).

Wired: If not Mach effects, what do you think is a better explanation for what could be producing this apparent thrust? Why do you feel its a better explanation?

Vibrating objects have artefacts that can appear to be thrust. If the thrust is real then it does not seem to agree with the Woodward theory anyway. I have suggested the theory of quantised inertia (McCulloch, 2007) which predicts galaxy rotation without dark matter and predicts some, not all, of the Mach effect tests (McCulloch, 2018). 


Rodal, J.A., 2019. A Machian wave effect in conformal, scalar–tensor gravitational theory. General Relativity and Gravitation, Volume 51, Article number: 64.

Mahood, T., 1999. Propellant-less propulsion: recent experimentla results exploiting transient mass modification. AIP Conf proc. STAIF-2000. AIP, 1014-20.

McCulloch, M.E., 2007. Modelling the Pioneer anomaly as modified inertia. MNRAS, 376(1), 338-342. 
McCulloch, M.E., 2018. Propellant-less propulsion from quantised inertia. J Space Exploration, Volume: 7(3).