Editorial

, Volume: 6( 2)

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Accelerating Universe Explained

*Correspondence:

Bhattacharya SC, Department of Physics, A. C. College West Bengal, India,Tel:+91 9831565833;E-Mail: [email protected]

Introduction

Accelerating universe is a puzzling problem for which no explanation is available. Here I attempt to give an explanation of the phenomenon from a different angle. The explanation of course depends on some assumptions which are reasonable. The assumptions are as follows:

1) The Universe is static which may be called Einstein’s Static Universe. This assumption is made for simplicity and will be withdrawn later.

2) A photon losesenergyas it passes through space. In other words photon is a decaying particle andlawof decay is exponential so that

,, where E=energyof photon at time t which is the time of observation.

E₀=Energyof photon at time t₀which is the time of emission.

λ = decay constant,

Hence,

Let Z be the Redshift then

D= Distance of galaxy from the observer, c= Velocity of light in vacuum

, when Z is small

Comparing with Hubble’slawwhere H=Hubble’s constant, we get λ=H

Thus we get

-------------------------------------(A)

-------------------------------------(B)

Now it may be asked how this universe will appear to an observer who believes in expanding universe but not in decay of photons. He will of course use a line element

………….(1)

He will also use the relation ,where symbols have their usual meaning

(2)

Comparing Equation (2) with Equation (B) it is clear that

,where R is a constant

We shall call S(t) apparent expansion function

现在,

……………..(C)

………………(D)

Equation (C) and (D) show that this universe is expanding and accelerating.

It is very important to note that due to the decay of photons even a static universe appears expanding and accelerating.

Now a static universe is unstable. Hence we must take an expandingmodelwith real expansion function f(t) say. Taking into account the decay of photon the apparent expansion function is,

In this caseas will be shown below.

Also,

The first term on RHS is negative and the second and third terms are positive. Ifis sufficiently smaller than the sum of second and third term thenwill be positive and the universe will appear accelerating though its acceleration is apparent not real.

Thus we come to the conclusion

1) Photon is a decelerating particle.

2) Acceleration of universe is apparent not real and due to the decay of photons.

3) The Universe is actually decelerating and the deceleration is small.

In fine it is interesting to notice some features of the Einstein’s staticmodelof the Universe together with the photon decay hypothesis, which are as follows.

1) It shows that the Universe is apparently expanding.

2) It proves Hubbles law.

3)它显示环宇e is accelerating apparently.

4) Acceleration is proportional to distance.

5) Constant of proportionality is H², where H= Hubble’s Constant

6) It gives a compact relation between redshift Z and distance

c ln(1+Z) = HD

References

1. Introduction to Cosmology ? J.V. Narlikar ? P-83 CUP, 2^ndEdition.