Age Of The Universe Essay Research Paper

Age Of The Universe Essay, Research Paper

The Age of the Universe

INTRODUCTION:

The goal of the project is to find the age of the universe according to the theory

that there were equal amounts of the two uranium isotopes U235 and U238 at

the time of the Big Bang. At present, there are 137.7 U238 atoms for each atom

of U235. We know that the half-life of U235 is 0.71 billion years, and the

half-life of U238 is 4.51 billion years, we used this information to determine the

age of the universe. We started by looking at the problem mathematically and

then after figuring out the age of the universe with the above information. We

proceeded to look for other sources of information about the age of the universe

with supporting data. The two largest sources that were found were a Seattle

University professor and a theory proposed by Edwin Hubble.

CALCULATIONS

Using the information above, we

Y238(t) = Y238(0)ekt = No ekt Where No ekt is initial amount presumed equal

for both isotopes.

Y238(0) is the amount at Big Bang.

Using the half-life formula of k = -ln2/T1. Where T1 is 4.51 in billion of years.

Y235(t) = Y235(0)ekt = No ekt

Y235(0) is the amount at Big Bang.

Using the half-life formula of k2 = -ln2/T2. Where T2 is 0.71 in billions of years.

Given these equations, they hypothesis of the problem is states that

Y235(tnow) 1

Y238(tnow) = 137.7

Y238(tnow)

Y235(tnow) = 137.7

So Y238(tnow) = Y238(0) ekt = No ek2tnow = etnow(k2-K1) = 137.7

Y235(tnow) Y235(0) ekt Noek1tnow

Given that tnow cancels out for both U235 and U238 we are left with the

equation of:

tnow ( -ln2 + -ln2) = 137.7

4.51 0.71

tnow ( .82257) = ln(137.7)

tnow (.82257) = 4.92508

solving for tnow:

tnow = 5.987 billion years.

So this theory estimates the age of the universe to roughly 6 billion years old.

COUNTERING THEORIES:

HUBBLE THEORY

In 1929, Edwin Hubble decided that because the light coming from most galaxies

was redshifted.

(The apparent change in wavelength of sound or light caused by the motion of

the source, observer or both. Waves emitted by a moving object as received by

an observer will be blueshifted (compressed) if approaching, redshifted

(elongated) if receding. It occurs both in sound and light. How much the

frequency changes depend on how fast the object is moving toward or away

from the receiver.)

Hubble concluded that the universe must be expanding after exploding from an

infinitesimal volume of super hot, super dense concentration of matter and

energy. The explosion is called the big bang, which propelled matter in all

directions and at all speeds. According to the big bang theory, the farther away

an object is from us, the more redshifted its light. Also, a greater redshift means

the object is moving away faster than objects with less redshift. In Designs and

Origins in Astronomy, Mulfinger explains the redshift technique for measuring

distances to distant galaxies. If the universe is not expanding, this cannot be true

and the redshift must be due to other causes. An astronomer can tell how old the

universe is by the rate of expansion. Cowen in 1994, clarifies that if the redshift is

due to something other than expansion, nothing can be said about the universe’s

age.

As we shall discuss further in connection with the big bang, there is strong

evidence that the Universe has not always existed, but instead came into being a

finite amount of time ago. There are several measures of the age of the Universe.

Let us discuss two: (1) the age of globular clusters and (2) the inverse of the

Hubble constant.

Globular Clusters

As a counter to the mathematical theory, globular clusters provide a measure of

the age of the cluster. A cluster is a system of galaxies containing from a few to a

few thousand-member galaxies, which are all gravitationally bound to each other.

Thus, the age of such clusters place a limit on the age of the Universe, for it must

be at least as old as the objects that it contains. Such estimates typically yield

ages in the range 14-18 billion years

Hubble Time

The inverse of the Hubble constant H has the units of time because the Hubble

law is

v = H d

where v is the velocity of recession, H is the Hubble constant, and d is the

distance. Thus, from this equation, we have that 1/H = d/v. but d/v is distance

divided by velocity, which is time (e.g., if I travel 180 miles at 60 miles/hour, the

time required is t = d/v = 180/60 = 3 hours).

Thus, the Hubble time T is just the inverse of the Hubble Constant:

T = 1 / H

Taking a value of H = 20 km/s/Mly (where Mly means mega-light years), where

all the factors are necessary to convert the time units to years (Cowen, 1994).

The physical interpretati

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