Imagine the Universe!
Imagine Home  |   Ask an Astrophysicist  |  
Ask an Astrophysicist

The Question

(Submitted February 11, 1998)

What is the amount of energy released in the Big Bang. Expressed in tons of dynamite or H-bombs, etc.

The Answer

Energy wasn't "released" per se - it's still contained within the event horizon, presumably.


Notation:
** is an exponent - ie x**2 means x squared.
* is a multiplication symbol
/ is a division symbol

The total mass-energy content of the universe today is of the order of the critical density,

  3 x H0**2/(8*pi*G) = 5 x 10**(-30) g/cm**3, 

times the volume contained within the present event horizon,

  (4/3)*pi*R**3,
 

where R = the event horizon = c * T (speed of light * age of Universe ) = 3 x 10**10 cm/s x (2/3)*(c/H0). Here H0 is the Hubble constant, assumed to be around 50 km/s/Mpc and Omega = 1 (critical deceleration). For this value of H0, 1/H0 = (app) 20 billion years, making the current age of the Universe about 2/(3*H0) = 13 billion years, so that

  R = (app.) 1.3 x 10**28 cm,
which should be equivalent to 13 billion light-years (1.3 x 10**10 y x 10**13 km/y x 10**5 cm/km).

This gives a total mass-energy mass of about 4.4 x 10**55 grams, equivalent to about 2.6*10**79 protons. The energy equivalent (E = m*c**2) of these protons is about 2.5x10**79 GeV or 2.5x10**88 eV * 1.6x10**-19 J/eV = 4x10**69 Joules.

One ton of TNT releases 4.2 x 10**9 Joules. Thus the energy equivalent of the mass=energy of the universe is about 9.5 x 10**53 Megatons of TNT. This is greater than the mass-energy of the universe, but only because the chemical process involved in exploding TNT is vastly less efficient that E = m*c**2.

Jim Lochner
for Ask an Astrophysicist (with help from Mark Kowitt, Mike Corcoran, and Leonard Garcia)

Previous question
Prev
Main topic
Main
Next question
Next

If words seem to be missing from the articles, please read this.

Imagine the Universe! is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Project Leader: Dr. Barbara Mattson
Curator: Meredith Gibb
Responsible NASA Official: Phil Newman
All material on this site has been created and updated between 1997-2014.
This page last updated: Thursday, 01-Dec-2005 13:58:38 EST