Skip to page content |

Tiscali Quicklinks. Please visit our Accessibility Page for a list of the Access Keys you can use to find your way around the site, skip directly to the main navigation, to the page content, or to more links within reference.

Advertisement starts



Advertisement ends

Content Starts Here


Big Bang (astronomy)

encyclopaedia header
Encyclopaedia Search
Click a letter for the index
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Or search the encyclopaedia:
 
 
 
all results tagged with the © symbol denotes content that is relevant to the national curriculum

Big Bang (astronomy)


In astronomy, the explosive event that marked the origin of the universe as we know it. At the time of the Big Bang, the entire universe was squeezed into a hot, superdense state. The Big Bang explosion threw this compact material outwards, producing the expanding universe seen today (see red shift). The cause of the Big Bang is unknown; observations of the current rate of expansion of the universe suggest that it took place about 10–20 billion years ago. The Big Bang theory began modern cosmology.

According to the modern modified version of the Big Bang theory, called the inflationary theory, the universe underwent a rapid period of expansion shortly after the Big Bang, which accounts for its current large size and uniform nature. The inflationary theory is supported by the most recent observations of the cosmic background radiation.

Present quantum theory and relativity theory break down when pushed back to earlier than 10-43 seconds, which is known as the Planck time. (10-43 is equal to 1÷1043; and 1043 is equal to 1 followed by 43 zeroes.) The present-day observable universe was then smaller than a proton and the temperature was 1032 K (kelvins – equal in size to degrees Celsius). Inflation began now or an instant later, and ended when 10-33 seconds had passed. The universe observable today was then a metre across.

One ten-thousandth of a second after the Big Bang, the temperature had decreased enormously, but was still 10 billion K (1010 K). Subatomic particles had formed by the collision of quarks. After 10 seconds, neutrons had combined with protons to form nuclei of deuterium (an isotope of hydrogen). The nuclei of deuterium then joined together to form helium nuclei. As the universe continued to expand for the next 300,000 years, the temperature cooled to 10,000 K. Under these conditions helium nuclei were able to join with electrons to form helium atoms. Some hydrogen nuclei joined to form lithium nuclei and thence lithium atoms. After millions of years, at lower temperature and pressure, the force of gravity was able to draw particles together. After millions more years, matter clumped together to form galaxies, stars, planets, and moons.

The first detailed images of the universe as it existed 300,000 years after the Big Bang were released by the US National Aeronautics and Space Administration (NASA) in April 2000. The images were created by mapping cosmic background radiation.

© Research Machines plc 2008. All rights reserved. Helicon Publishing is a division of Research Machines plc.


 
 

Advertisement starts



Advertisement ends


Barbados Flag
Barbados Flag Blue represents the sea and the sky. The points of the trident represent the three principles of democracy: government of, for, and by the people. Effective date: 30 November 1966. >>

Advertorial

AdvertorialFind out how to buy the things you've always wanted and sell the things you don't on ebay.

Advertisement starts



Advertisement ends

Page Footer


Access keys


You will need to use different key combinations in order to use access keys depending on your internet browser, find out which on our accessibility page.
  • (0) Navigate to Accessibility page.
  • (1) Navigate to Home page.
  • (2) Navigate to My email.
  • (3) Navigate to My Account.
  • (4) Navigate to Site Map page.
  • (5) Navigate to Contact us page.
  • (6) Navigate to Members channel.
  • (7) Navigate to Services channel.
  • (8) Navigate to News & Info channel.
  • (9) Navigate to Entertainment channel.
  • ([) Skip down to the Primary navigation block.
  • (]) Skip down to the more links within this section block.
  • (=) Bypass all navigation and jump to the content.