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Related Concept Videos

Formation of Species01:31

Formation of Species

Speciation describes the formation of one or more new species from one or sometimes multiple original species. The resulting species are discrete from the parent species, and barriers to reproduction will typically exist. There are two primary mechanisms, speciation with and without geographic isolation—allopatric and sympatric speciation, respectively.Allopatric SpeciationIn allopatric speciation, gene flow between two populations of the same species is prevented by a geographic barrier, like...
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Speciation Rates

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Phase Transitions: Melting and Freezing02:39

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Metallic Solids02:37

Metallic Solids

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Entropy Changes Accompanying Specific Processes

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Related Experiment Video

Updated: Jun 21, 2026

Gold Nanostar Synthesis with a Silver Seed Mediated Growth Method
12:39

Gold Nanostar Synthesis with a Silver Seed Mediated Growth Method

Published on: January 15, 2012

The morphological evolution of galaxies.

R G Abraham1, S van Den Bergh

  • 1Department of Astronomy and Astrophysics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 3H8, Canada. abraham@astro.utoronto.ca

Science (New York, N.Y.)
|August 18, 2001
PubMed
Summary
This summary is machine-generated.

Galaxy appearance has evolved significantly over cosmic time, with complex structures like spiral arms becoming less common in the early Universe. However, the number of luminous disk galaxies has remained consistent since redshift 1.

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Last Updated: Jun 21, 2026

Gold Nanostar Synthesis with a Silver Seed Mediated Growth Method
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Published on: January 15, 2012

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Published on: June 7, 2018

Evolution of Staircase Structures in Diffusive Convection
07:28

Evolution of Staircase Structures in Diffusive Convection

Published on: September 5, 2018

Area of Science:

  • Cosmic evolution
  • Galaxy morphology
  • Astrophysics

Background:

  • Galaxy appearance has changed significantly over cosmic time.
  • Early universe galaxies exhibit distinct morphologies compared to local galaxies.

Purpose of the Study:

  • To investigate the evolution of galaxy morphology over cosmic time.
  • To understand how galaxy populations have changed since the early universe.

Main Methods:

  • Analysis of galaxy morphology at various redshifts (z).
  • Comparison of distant galaxy features with local galaxy classifications.

Main Results:

  • Significant deviations in galaxy morphology observed at redshifts as low as z = 0.3.
  • Spiral arms are less developed and barred spiral galaxies appear rarer beyond z = 0.5.
  • At z = 1, a substantial fraction of galaxies are too peculiar for traditional classification.
  • The space density of luminous disk galaxies has remained constant since z = 1.

Conclusions:

  • Galaxy familiar forms are relatively recent.
  • While individual galaxy appearances evolve, the population of luminous disk galaxies has been conserved since redshift 1.