Ambjørn, Jan

Jan Ambjørn
The Niels Bohr Institute (NBI)
Copenhagen University
Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark

ArXiv: (The Universe from Scratch, (PDF),2005
A model for emergence of space and time, J. AmbjornY. Watabiki, 2015
Reconstructing the universe, 2005
Books: The Geometry of Dynamical Triangulations, Springer 1997
Google Scholar
Homepage (NBI): DBpedia (About) Radboud (RU), Worldcat
YouTube: With Wolfram, August 2021

Most recent email: 5 February 2022 @ 5:30 PM

Dear Prof. Dr. Jan Ambjørn:

In my first note to you in 2016, I never properly introduced myself. I apologize. High school teachers can be, unwittingly, as presumptuous as Nobel laureates. Of course, each of us is so tied up within our own work, we become oblivious to others.

In 2011 in our geometry class we did a base-2 progression to the Planck scale. From the classroom it is only required us to divide by two 112 times (smaller and smaller steps within). We also went out, multiplying by two (or doubling), and we found only 90 steps going out. The universe was encapsulated within 202 notations from the first instant to this day, from the smallest to the largest.

We then asked about Planck’s base units. What could be smaller? What would something look like if the first instance of space-time was defined by the basic four units? What would it look like? Might it be an infinitesimal sphere? We consulted with old friends (Freeman Dyson), with folks like Frank Wilczek at MIT, and specialists at NIST, Codata, Durham University Institute for Particle Physics Phenomenology and so many others.

Because I am older now and my memory is not as good as it could be, I have reference pages to the work of key scholars with my little notes and questions. My page for you is here:ørn/ Although our models for the emergence of space-time may appear very different, there will come a day that they’ll be reconciled! Thank you for all that you do.

Most sincerely,


Second email: 13 July 2021 at 12:23 PM

Dear Prof. Dr. Jan Ambjørn:

Thank you for your work to develop Causal Dynamical Triangulations (CDT)
where Wikipedia cites you as the prime mover for its development.

The Planck scale is difficult for most of us.
1. Did Max do a reasonable job defining the base units?
John Ralston (Kansas) believes Planck’s Constant throws it all off.
Reference: Quantum Theory without Planck’s Constant, (PDF), Mar 2012
2. Do the Planck base units define (or metaphorically define) the first instant of the universe?


First email: November 19, 2016, 10:20 PM (lightly updated)

The Universe from Scratch, 2005. 
The Geometry of Dynamical Triangulations (Springer 1997)
ArXiv (113)
A model for emergence of space and time, 2015

Dear Professor Jan Ambjørn:

Thank you for all your work.  Very, very helpful. I first found you within ArXiv.  Though well along in years (69 years old), you have embraced topics which I find most fascinating.  So, you have a new  student (de facto)!

I will attempt to digest your writings to give me insight in order to write a sequel to my post yesterday: “Simple Math-Geometry-And-Logic Render A Simple Model Of The Universe” or

Of course, I would be honored with even your cursory look and comments.

Most sincerely,


Institute for Theoretical Physics, Utrecht University,  Minnaert Building,
Leuvenlaan 4, NL-3584 CE Utrecht, The Netherlands