Of course, testable predictions used to be a fundamental requirement for any scientific theory – so far. But then, we are (were?) in a similar situation with string theory. A parallel in the past? Of course: Albert Einstein thought that there was no way to one day measure gravitational waves – and look where we are now! (Similar thing with black holes.) As for strings, there has been a hint of a discovery of a cosmic string, following a relatively simple theory about what to look for. All of this amounts to the obvious answer that of course, scientific methods should not be changed; the challenges are just higher than ever before.

The key is that inflation is just a theory.

Science, especially Cosmology needs multiple view points a.k.a theories. Whether hey are testable or not is for the future generations. Floating a theory, however outlandish it is, shows the design of the human intellect and imagination. Many conjectures in Mathematics are yet to be proved. Fermat’s last theorem has been proved only recently. Like Law, an accused is not guilty until proven, should be applied to Cosmological Principles. Every Professor will have his pet theories and Dr. Paul Steinhardt is no exception. Stephen Hawking asserted that nothing escapes from Blackhole, but he observed the radiation emanating from a blackhole, which was later termed as Hawking Radiation. Even if we sum up all the humanity’s total intelligence and apply it to cosmology, still it will be short by 95% as most of our laws are tried in the visible spectrum only. We hope that some spark like a Big Bang will occur in the sub conscious state of human mind which may explain the state of nature. Incidentally, the Rishis of East have been advocating that one needs to look inwards to understand the outwards.

I opine that having a key , which is a theory is more substantial and more approving than being without one. It shows that we have the capability to think and not being able to provide tangible tests to support inflation theory does not lead to automatic cancellation of the theory rather it invokes us to think beyond the scope. Until a more proven theory is available, we should work with already set theories

The cyclic model is an interesting idea and it must be extracted from first principles and models suchs as String Cosmology or Loop Quantum Gravity. We launch the questions? Are there other versions of this picture?

Maybe reality simply allows everything that can happen to happen and doesn’t care about your scientific rigor. How do you know that’s not the case?

The problem is, in simple words, is like asking what is the product of 0 times infinity.

The likelihood that we happen to exist in a multiverse is infinitesimal. But since everything that can happen will happen an infinite number of times says that there is an infinitude of us peppered in the multiverse. So our probability of existing times the number of times we exist in the multiverse is (pick a number!).

In short, the argument professor Steinhardt makes is convincing but not fatal.

I accept that inflation is eternal but where along this eternal inflation are we? Has inflation been on-going infinitely long? (I doubt it.. nature seems to abhor infinities).

SO, by the anthropic principal, since we exit, a universe compatible with our existence had to have formed and we exist. I accept that there is an untold (I calculate gogolplex +3 of them, for sure ;-))number of universes that also contain something like us.

The scientific method is important, but cosmic theories will always take time to prove or disprove. The more theories the better, and the more experimental physicists out there working on them the better.

Hello Ladies and Gentlemen,

A theory that is untestable is not a good theory.

The the caveat it is unprovable occurs.

The question about the Scientific Method is beyond my authority.

If inflation theory is untenable in new science, this is what is questioned. To question the scientific method itself seems a very wikipedia age event- hacking the system.

Some say our era allows us to have this right to hack.

We just have theories

I think it is good and with the development of technology we will can do experiments to prove it.

Any theory that develops such high probability of being wrong in any other science would be enough to disprove said theory, so why not this one?

Science = theory + test … and again and again, … The Sigma check …

A theory without testable predictions challenges the scientific method’s core principle of empirical verification. Testable predictions are vital for confirming or refining theories. Changing the scientific method to accommodate non-testable theories risks undermining scientific rigor and accountability. While openness to new ideas is important, maintaining testability and empirical evidence ensures the integrity of scientific inquiry. Adapting the method while preserving its core principles allows for progress and innovation within a structured framework.

A theory which has failed to prove anything, was picked in order to make things turn out life they are, and leads to a conclusion that Anything and Everything will happen an infinite number of times, seems by Occam’s razor alone to be an indication that we have taken a wrong turn somewhere!