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  2. Crystallographic restriction theorem - Wikipedia

    en.wikipedia.org/wiki/Crystallographic...

    Thus 5-fold rotational symmetry cannot be eliminated by an argument missing either of those assumptions. A Penrose tiling of the whole (infinite) plane can only have exact 5-fold rotational symmetry (of the whole tiling) about a single point, however, whereas the 4-fold and 6-fold lattices have infinitely many centres of rotational symmetry.

  3. Rotational symmetry - Wikipedia

    en.wikipedia.org/wiki/Rotational_symmetry

    Rotational symmetry of order n, also called n-fold rotational symmetry, or discrete rotational symmetry of the n th order, with respect to a particular point (in 2D) or axis (in 3D) means that rotation by an angle of ⁠ ⁠ (180°, 120°, 90°, 72°, 60°, 51 3 ⁄ 7 °, etc.) does not change the object. A "1-fold" symmetry is no symmetry (all ...

  4. Alan Lindsay Mackay - Wikipedia

    en.wikipedia.org/wiki/Alan_Lindsay_Mackay

    He is a pioneer in the introduction of five-fold symmetry in materials and in 1981 predicted quasicrystals in a paper (in Russian) entitled "De Nive Quinquangula" [3] in which he used a Penrose tiling in two and three dimensions to predict a new kind of ordered structures not allowed by traditional crystallography.

  5. Penrose tiling - Wikipedia

    en.wikipedia.org/wiki/Penrose_tiling

    The pattern represented by every finite patch of tiles in a Penrose tiling occurs infinitely many times throughout the tiling. They are quasicrystals: implemented as a physical structure a Penrose tiling will produce diffraction patterns with Bragg peaks and five-fold symmetry, revealing the repeated patterns and fixed orientations of its tiles ...

  6. Symmetry - Wikipedia

    en.wikipedia.org/wiki/Symmetry

    Symmetry in physics has been generalized to mean invariance—that is, lack of change—under any kind of transformation, for example arbitrary coordinate transformations. [17] This concept has become one of the most powerful tools of theoretical physics, as it has become evident that practically all laws of nature originate in symmetries.

  7. Searchers don’t expect to find Pennsylvania woman alive in ...

    www.aol.com/searchers-don-t-expect-pennsylvania...

    Pollard’s family called police at about 1 a.m. Tuesday to say she had not been seen since going out at about 5 p.m. Monday to search for Pepper, her cat.

  8. Braarudosphaera bigelowii - Wikipedia

    en.wikipedia.org/wiki/Braarudosphaera_bigelowii

    The family Braarudosphaeraceae consist of single-celled coastal phytoplanktonic algae with calcareous scales with five-fold symmetry, called pentaliths. With 12 sides, it has a regular dodecahedral structure, approximately 10 micrometers across. [2] [3] (A) SEM image of a cell of B. bigelowii surrounded by 12 pentaliths.

  9. How to drink less during the holidays: 5 expert tips to help ...

    www.aol.com/lifestyle/drink-less-during-holidays...

    That could mean inviting friends over to check out the holiday light displays in your neighborhood (with mugs of hot chocolate at the ready) instead of hosting a cocktail party.