Griffon

You do not to have to go into physics of course after your degree. What else interests you? For example I understand the financial sectors still look for bright graduates in theoretical physics and mathematics. Most of the theorists I have known have been part of experimental research groups and by and large not in those areas we normally associate with theoretical physics like cosmology, particle physics and so on. They have been theorists in atomic physics, condensed matter physics, laser physics and so on. So it's far from true that theorists only work at the edges of physics in fields like string theory. Theorists bring very necessary skills in mathematical techniques, computing and understand the underlying physics to an experimental research group. The theorists very often set the direction of the research too. So, in your position I might look at what areas are currently topical and being funded in your country. Discover which are the most successful research groups. Maybe apply to do a PhD with a theoretical bias in one of those successful groups. Also think about the areas of physics that interest you apart from the standard ones you've mentioned.

I'm not that keen on faith education. I'd rather children were taught to be rational, to think and to question. But I have to say that fundamentalist secularists worry me too. I'd rather live in a society that was tolerant of different ways of life, which includes parental freedom to choose how their children are educated.

Yes. I see what you mean. In such circumstances I might imagine we could say the possibility of life elsewhere was vanishingly small, in a finite universe anyway. But we could never be certain that somewhere in a galaxy far far away life like ours had also developed. I also find such a scenario depressingly bleak.

It depends what it is we are saying. I was taking the OP's question "What if aliens didn't exist?" to mean just that: didn't exist anywhere. I can't see how we could know that for sure. We might be able to say they don't exist in a more limited sense, within our solar system say, or even further afield eventually. We could indeed be the first intelligent species to populate the galaxy.

What's your interest, Petrushka?

Interesting question. I know a fair bit about lasers and almost nothing about masers apart from their use as atomic clocks, communications, radar etc. I suppose the most obvious difference is wavelength. Lasers cover the near IR to x-Ray region of the EMS whilst masers are in the microwave region.

I can't see how we could possibly know there were no intelligent extraterrestrial life forms apart from ourselves. We would have to have explored the whole universe to know that. In the very distant future we might be able to conclude that there are no detectable technologically capable alien civilisations in our galaxy. If this turns out to be true it would indicate just how rare are civilisations like our own - and profoundly influence our view of ourselves as a species.

Quite. My last sentence woud have been better put the other way around. I can think of few things more closed minded than accepting "miracles, omens, etc." as truths.

I pick up on the following sentence. "Many things are not explainable by the conventional scientific logic which does not accept many truths like miracles, omens, etc and tries to answer every question with not a very open view." L I can think of few things more closed minded than accepting the truths of "miracles, omens, etc."

Wouldn't the two masses have to start accelerating towards one another from an infinite distance apart? I'm imagining a universe consisting only of two equal masses set initially at some distance apart.

I'm not sure what you're saying exactly. I agree a theory can be shown to be false by experimental result. My point is that not all explanations can be shown to be false. For such explanations there is no observation or experiment you can make that can show the explanation to be false. The theory that an undetectable goblin moves my car keys about so I cant find them is such an explanation. [if only I could catch the blighter though!] Such explanations are unscientific. For an explanation to be described as scientific it must be possible, in principle, to show that it is false. The discovery that neutrinos travelled faster than the speed of light would have been sufficient to falsify relativity as it stands. That's what's meant by "falsifiable".

I see what you're saying. But doesn't string theory make predictions that we can't test, and won't be able to test if ever because of the inaccessible energies required. Mind you, I suppose the same might be said of theoretical considerations of the conditions at the earliest time within the Big Bang. I suppose all we can do when experiments are not possible is to see how well the theory predicts what we see now.

True. So perhaps scientists should be more careful. So, should string theory be considered a scientific theory? Lee Smollin has his doubts. Perhaps it's a branch of mathematics? PS How odd. I keep trying to add this comment on ST as separate post, but it keeps adding it to this post. Doesn't this forum allow you to post twice in a row?

Yes, that is true. Although the level of the question is an indication of a sort.

Yeah, you're postulating an eternal entity. There's nothing in the cosmological argument that self evidently points to the existence of such an entity, let alone that it is what you call the Christian God. The arguments just don't stack up. PS is it really so bad not knowing the true origins of the universe?