What is Penrose: Definition and 91 Discussions

The Penrose triangle, also known as the Penrose tribar, the impossible tribar, or the impossible triangle, is a triangular impossible object, an optical illusion consisting of an object which can be depicted in a perspective drawing, but cannot exist as a solid object. It was first created by the Swedish artist Oscar Reutersvärd in 1934. Independently from Reutersvärd, the triangle was devised and popularized in the 1950s by psychiatrist Lionel Penrose and his son, prominent Nobel Prize-winning mathematician Sir Roger Penrose, who described it as "impossibility in its purest form". It is featured prominently in the works of artist M. C. Escher, whose earlier depictions of impossible objects partly inspired it.

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  1. R

    Roger Penrose´s OR theory, Consiousness is a QM phenomenon?

    I read a summary about the OR theory by Penrose, the problem is; why would QM has anything to do with consiousness? It seems now that when scientists cant explain something, the say its a QM phenomenon. QM theory has replaced philosophy and religion. Its a little more scientific so they don have...
  2. vinicius_linhares

    A Newmann-Penrose Spin coefficients for Schwarschild metric

    I need to use the N-P formalism to apply in my work so I'm trying first to apply in a simple case to understand better. So in this article ( https://arxiv.org/abs/1809.02764 ) which I'm using, they present a null tetrad for the Schwarszchild metric in pg.14 (with accordance with the...
  3. P

    I Is Penrose's Cyclic Cosmology Model Only Applicable on a Local Scale?

    A recent thread asked about Penrose's proposal on cyclic cosmology. It was closed due to lack of any remotely acceptable sourcing, even after prompting. Much of the original professional publication on this is not available on arxiv. However the following includes a summary of conformal cyclic...
  4. PeterDonis

    A Connectedness of Boundary Points in Schwarzschild Penrose Chart

    In the Penrose chart for Schwarzschild spacetime, the boundary "at infinity" appears to be connected all the way around. I want to explore what that means physically and whether particular boundary points that appear to be connected on the chart actually are. I am using the following notes as a...
  5. S

    B Penrose Diag Black Hole: Riddle Me This

    I'm no expert in this stuff, and perhaps I don't understand these diagrams, but having said that, I don't understand why the typical Penrose diagrams I see of black holes look the way that they do. They all have a 45 degree (light speed) angle for the event horizon of the black hole, and they...
  6. E

    I A bit confused with this question about the Penrose process

    The first two parts to the question were as follows. If a vector field ##\xi## preserves the Maxwell field then ##\mathcal{L}_{\xi} F = 0## so by Cartan's magic formula ##i_{\xi} \mathrm{d}F + \mathrm{d}(i_{\xi} F) = 0##. But since ##\mathrm{d}F = 0## then ##\mathrm{d}(i_{\xi} F) = 0 \implies...
  7. iosman001

    Other The Road to Reality by Penrose?

    Hello, i live in the US and decided to get this book off of amazon i was wondering if anyone has read, or atleast skimmed (its pretty big) through it and would mind telling me if its a good buy(although if it isnt, its a little late now :-p). also, I am pretty new to most of the theories. all...
  8. fresh_42

    I Penrose's Latest Paper on CCC: Evidence or Wishful Thinking?

    What do you think about Penrose's latest paper on CCC? (highlights mine) https://arxiv.org/pdf/1808.01740.pdf https://www.resonancescience.org/blog/Physicists-Think-They-Spotted-the-Ghosts-of-Black-Holes-from-Another-UniverseThe question is: Has he finally found some evidence for CCC, or is...
  9. E

    Penrose equation for a vacuum spacetime

    Okay so for this one we can consider the Bianchi identity again$$\begin{align*} \nabla_{[\lambda}R_{\sigma \rho] \mu \nu} = 2 \nabla_{\lambda} R_{\sigma \rho \mu \nu} + 2\nabla_{\rho} R_{\lambda \sigma \mu \nu} + 2\nabla_{\sigma} R_{\rho \lambda \mu \nu} &= 0 \\ \nabla^{\lambda}...
  10. P

    I Penrose Diagram for Minkowski Space-Time: Step-by-Step Guide

    I'm working through Ray d'Inverno's book "Introducing Einstein's Relativity" and I've got to the section that introduces Penrose diagrams. The first example is just Minkowski space-time. The construction goes from Schwarzschild coordinates ##t## and ##r##, to define null coordinates ##v = t +...
  11. U

    A The Penrose gravity thesis/interpretation of QM

    The Penrose interpretation postulates that the wave function is real and that there is objective collapse without departing from reality as we know it. It does not make any assumptions; the observations of quantum mechanics and classical mechanics are exactly what they appear to us. "Accepting...
  12. W

    I Penrose Singularity: Trapped & Anti-Trapped Surfaces Explained

    As I understand Penrose proved there must a be a singularity using certain assumption for black holes and something called a "trapped surface:. Can anyone give a lay person explanation of what this and "anti trapped surface" are? How were they used in the singularity theorems and what was new...
  13. D

    Cosmology Is Road to Reality by Penrose Suitable for Non-Experts?

    I recently acquired the tome of Penrose's Road to Reality. I'm trying to figure who this book is intended for. It has a mix of deep mathematical physics concepts with light explanatory diagrams. I have a little bit of a mathematical background, bachelors in math, so I can follow it pretty...
  14. S

    A Penrose diagram of black hole with a changing event horizon

    Dear all, I have a question on Penrose diagrams. Consider a collapsing star that forms a black hole with a Schwarzschild radius normalized to 1. What happens in the Penrose diagram when additional matter falls in? I suspect the diagram then has to look like this : When the outer shell (second...
  15. S

    Can twistor theory be used to describe everything?

    I've been looking at another Penrose's theory/model called twistor theory (https://en.wikipedia.org/wiki/Twistor_theory) that seems very interesting. From what I've read it seems to me that literally everything can be represented by twistors (or, rather, variations of twist theory). The only...
  16. Auto-Didact

    Who is Penrose Sir Roger Penrose? Insights from His Recent Interviews

    Sir Roger Penrose, famous for his numerous contributions to mathematics and physics, is approaching 90 but still pretty active. In this thread I'll post some of his most recent and best interviews. The interviews tend to be a mixture of him talking about some new idea of his, his prior academic...
  17. nomadreid

    I 1-dim Penrose tiling = "musical sequence"? Why?

    In several places (e.g., page 12 of http://www.cs.williams.edu/~bailey/06le.pdf), I have come across the aperiodic intervals in a one-dimensional Penrose tiling as "musical sequences". I do not see the connection between aperiodicity and music. The history of a fruitless but amusing search: (a)...
  18. Abhishek11235

    A Penrose paragraph on Bundle Cross-section?

    I am reading "Road to Reality" by Rogen Penrose. In chapter 15, Fibre and Gauge Connection ,while going through Clifford Bundle, he says: .""""...Of course, this in itself does not tell us why the Clifford bundle has no continuous cross-sections. To understand this it will be helpful to look at...
  19. Auto-Didact

    A Penrose: CCC predicts BICEP2 B-modes due to void magnetic fields, correlated to CMB Hawking Points

    Very recently, Roger Penrose, along with Daniel An and Krzystztof Meissner, have submitted a new paper to PRL. In the new paper they present new empirical findings which support CCC. It doesn't seem to be out yet though, I can't find it anywhere, but I will place the link here when it is out...
  20. Auto-Didact

    A Erebons: Planck mass Dark Matter particles

    Erebon theory is a novel explanation of dark matter recently invented by Roger Penrose. Erebons are scalar particles of the order of a Planck mass which can only interact gravitationally. When erebons decay, they release their energy as oscillating classical gravitational waves on the order of...
  21. Auto-Didact

    A Penrose: Noise in LIGO signal implies CCC

    Roger Penrose, July 2017. Correlated "noise" in LIGO gravitational wave signals: an implication of Conformal Cyclic Cosmology
  22. Auto-Didact

    B Can you solve Penrose's chess problem and win a bonus prize?

    Source: http://www.telegraph.co.uk/science/2017/03/14/can-solve-chess-problem-holds-key-human-consciousness/
  23. S

    A Penrose Process & Hawking Area Theorem Explained

    Hawking area theorem says that area of black hole generally never decrease. Penrose process says that energy can be extracted from black hole. Energy extraction will decrease mass? if yes then if mass is decreased then will area also decrease? I am confusing things here :(
  24. Gosutag

    I The Road to Reality by Roger Penrose

    Just started reading this book as an introduction to physics with a background of electrical engineering. It is absolutely fascinating and being new to the forum I'd appreciate it if anyone had any suggestions for further general learning. Thank you all for inspiring me to learn more physics...
  25. B

    B Penrose collapse and Superposition

    According to Sabine http://backreaction.blogspot.com/2016/03/dear-dr-b-what-is-difference-between.html you can make superposition go away by just changing the basis state.. "All this is just to say that whether a particle is or isn’t in a superposition is ambiguous. You can always make its...
  26. K

    I How do string theorists reply to Roger Penrose

    Roger Penrose’s http://press.princeton.edu/titles/10664.html']Fashion,[/PLAIN] Faith and Fantasy in the New Physics of the Universe "Arguing that string theory has veered away from physical reality by positing six extra hidden dimensions, Penrose cautions that the fashionable nature of a...
  27. Auto-Didact

    Happy 85th Birthday, Sir Roger Penrose

    Roger Penrose, of course, needs no introduction. At 85 he is as productive as ever, publishing papers, giving guest lectures. He also has a new book on the way and a kid currently in primary school. Here is a somewhat recent interview detailing a few aspects of his life. Happy birthday to you...
  28. A

    A How Does the Penrose Process Allow for Energy Extraction from a Black Hole?

    Hi everyone, I am a bit confused about the Penrose Process. Let's say a particle with energy E at infinity arrives in the ergoregion of a Kerr black hole and then it decays into two photons. One of them has L_1<0 and E_1<0 and hence it falls towards the singularity, while the other has L_2>0...
  29. twistor

    A What's the truth behind CCC's concentric circles prediction for the CMB?

    http://arxiv.org/pdf/1510.06537v1.pdf I found this semirecent paper about CCC's concentric circles prediction for the CMB. Is this just another piece of the debate, or is its significance enough to increase the plausibility of Penrose's model? Thank you in advance for your answers, and please...
  30. T S Bailey

    Is the firewall explained by the Penrose interpretation?

    The firewall has been proposed to explain why entanglement monogamy isn't violated in the AMPS thought experiment. The firewall is hypothesized to break the entanglement between the particle pairs of Hawking radiation created near the horizon so that the total sum of radiation emitted by the...
  31. M

    Can Penrose Stairs Exist on a Torus? Exploring the Possibilities

    Nobody mentions that Penrose stairs is possible on the torus. I wonder Why. isn't this obvious?
  32. S

    Riemannian Penrose Inequality: Proof Restriction to n=3?

    I am reading the proof of the Riemannian Penrose Inequality (http://en.wikipedia.org/wiki/Riemannian_Penrose_inequality) by Huisken and Ilmamen in "The Inverse Mean Curvature Flow and the Riemannian Penrose Inequality" and I was wondering why they restrict their proof to the dimension ##n=3##...
  33. K

    A Penrose twistor theory correctly predicts 4 dimensions

    string theory predicts dimensions but predicts 10 dimensions. Penrose twistor theory correctly predicts 4 dimensions, doesn't this make it more successful?
  34. R

    Penrose Diagram for Multi-Blackhole Solutions: Reference

    Can anybody recommend a reference (paper/textbook) where I can look up the Penrose diagram for multi-black hole spacetimes or multi-center solutions? Appreciate.
  35. N

    Can string theory and Penrose interpretation coexist?

    Can the M theory/ string theory coexist with the penrose interpretation of quantum mechanics?
  36. naima

    Penrose Diagrams: How to Create with Known Spacetime Metric

    Hi Pfs Is there a method to draw a Penrose diagram when the spacetime metric is known? Thanks.
  37. Jimster41

    Trouble understanding 2-side BH Penrose diagram

    I've seen this a few times now, but it's not quite sinking in? How are the left and right sides of that 2-side BH Penrose diagram disconnected but share the BH? I keep thinking you could go around the black hole. Trying to think of a metaphor that correctly captures my confusion. Picturing a...
  38. P

    Question about the Penrose process

    Can anyone tell me how energy created via the Penrose process can be extracted and converted into useable energy? What kind of infrastructure would we need on Earth, in space, etc.? Many articles talk about how energy can be created through the Penrose / Blandford–Znajek process, but none...
  39. bcrowell

    Necessary conditions for a Penrose diagram?

    What conditions are necessary if it's to be possible to make a Penrose diagram for a 3+1-dimensional spacetime? It seems that rotational symmetry is not necessary, since people draw Penrose diagrams for Kerr black holes. If you don't have rotational symmetry, how do you know what 2-surface is...
  40. C

    Penrose Diagram for the Kerr Black Hole

    Hey Guys, so i was reading Hawking&Ellis a bit and still encounter always problems with the Penrose-Diagrams. Looking at the Penrose-Diagram for the rotating Kerr-Black hole (just one illustrating picture at the end) i come up the following question: Why are there TWO regions III and III ? In...
  41. binbagsss

    Black Hole Penrose Process: Understanding Negative Energy Condition

    ##E= -T^uP_u ##, where ##T^u## is the time-like killing vector associated with the Kerr Metric and ##P_u## is the 4-momentum of the particle. ##E## is the energy. Outside the ergosphere ##T^u## is time-like and inside the ergosphere it is space-like. Therefore it can be arranged within the...
  42. G

    Einstein's Regret: Penrose Asserts on Relativity

    In the following program http://www.bbc.co.uk/programmes/b02144gl Penrose asserts that Einstein regretted the term relativity because it gave ammunition to those who assert that there is not one truth or that reality is a social construct. Does anyone have exact quotes from Einstein asserting...
  43. marcus

    Radical new cosmic model (Barrau Linsefors one-up Penrose)

    ==from conclusions section on page 4 of Barrau Linsefors June paper== V. REBIRTH OF THE UNIVERSE AND TESTS OF THE MODEL In the far future, huge patches of our universe, with radii larger than the Hubble scale, will be completely empty. They will be pure dS spaces. If the model suggested in this...
  44. twistor

    BICEP2 & Penrose: Inflation's Impact on Proving Initial Conditions

    If inflation is proven by BICEP 2, then what happens with Penrose's proof that infaltion assumes unprobable initial conditions?
  45. nomadreid

    Conne's indexing construction for Penrose tilings

    in Appendix D, pp. 179 ff, of Alain Conne's "Noncommutative Geometry", he outlines a process. He looks at Penrose tilings of the plane which are composed of two types of triangles L [with 2 longer sides of length \phin+1, and one shorter side of \phin) for integers n, whereby \phi is the...
  46. wolram

    Sir Roger Penrose: Challenging Modern Physics Theories

    http://www.sciencefriday.com/segment/04/04/2014/sir-roger-penrose-cosmic-inflation-is-fantasy.html What does Sir Roger know that others do not. Sir Roger Penrose calls string theory a "fashion," quantum mechanics "faith," and cosmic inflation a "fantasy." Coming from an armchair theorist...
  47. J

    Penrose Diagrams - Introduction

    Penrose Diagrams -- Introduction I'm woefully ignorant of a lot of things in GR, and now that I'm moving away from my comfortable spot in condensed matter, I'd like to know how to interpret Penrose diagrams. I'm having trouble understanding what it is they're actually showing and why they'd be...
  48. smodak

    Question on Chapter 7 : Penrose Road to Reality

    A little about my background. I have a undergraduate degree in physics which I obtained exactly 20 years back. I also have a undergraduate degree in EE which I obtained about 17 years back. I have worked as a software engineer all my life and currently also pursuing my MBA in Finance. Needless...
  49. C

    Is SU(2) a True Gauge Group in Light of E8 and Penrose's Views on Symmetry?

    Hello everyone- I've tried to keep up with E8, but lately the Google-ing isn't as productive as it used to be. I assume that there has been no Show Stopper and the push for E8 Unification continues. So: Concerning the E8 development: Roger Penrose states in _The Road to Reality_ p. 653...
  50. micromass

    Intro Physics The Road to Reality by Penrose

    Author: Roger Penrose Title: The Road to Reality Amazon Link: https://www.amazon.com/dp/0679776311/?tag=pfamazon01-20 Prerequisities: High-school mathematics and physics (in principle) Contents: