Meanwhile, Narlikar told IANS that their research was 'not intended as a theory but a suggestion for further exploration into this aspect.'

'We intended that there should be more research and studies on this subject. If somebody has done it, it is good,' he said.

However, in a separate written reaction, Narlikar said that he had seen Vaidya's paper and found it 'somewhat superficial in its reasoning.'

'One important aspect missed by the author is that these micro-organisms have not come directly from a comet. They were trapped in the Earth's atmosphere and would take some weeks to remain there as argued by the (late Sir Fred) Hoyle-Wickramasinghe theory of panspermia,' he said, adding the micro-organisms would get used to gravity.

'Arguments against panspermia used to be made on the grounds that they would not survive in the hostile radiation in the interstellar space. Experiments at the Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) have however shown that under doses of radiation like UV, X-rays and gamma rays, bacteria mutate and learn to survive.

'I think one should be more cautious in rejecting the panspermia hypothesis and do further experimentation on microlife in interstellar space. Future work on cometary material will throw light on this issue. The author (Vaidya) rejects the panspermia hypothesis but has no suggestion as to how the micro-organisms got there from the earth,' he said.

The paper was rejected by reputed journals in astrobiology several times and hence has found a place in a non-specialist magazine, Narlikar added.

On the other hand, Vaidya's mentor and biologist Arun Dholakia said the entire panspermia theory would now 'change or have to be re-written.'

However, he said it would take some time before the scientific community comes to terms with Vaidya's research. 'But, I am happy that at least a debate has been initiated and the outcome would only benefit science and the scientific community,' he said.

(Quaid Najmi can be contacted at q.najmi@ians.in)