Who's familiar with the conversion? - "In 15 years' ship-time they could reach Andromeda

yes

Let's cut to the chase... just to show you that things don't always just add up (the way you are trying to make them add up).

How far away is New York City for my brother in Rochester (as the crow flies)?

In the book, Hawking indicates that space expansion is not subject to the limitation of the speed of light.

The speed of inflation after Big Bang is speculated to be million times faster than light.

In the early 1970s, David J. Gross exposed the hidden structure of the atomic nucleus. In 2004, he shared the Nobel Prize in Physics...And today he struggles mightily to describe the basic forces of nature at the Planck scale...

Gross characterizes theoretical physics as rife with esoteric speculations, a strange superposition of practical robustness and theoretical confusion. He has problems with the popularizing of “multiverses” and “landscapes” of infinite worlds, which are held up as emblematic of physical reality. Sometimes, he says, science is just plain stuck until new data, or a revolutionary idea, busts the status quo....

Gross: "There are frustrating theoretical problems in quantum field theory that demand solutions, but the string theory “landscape” of 10*500 solutions does not make sense to me. Neither does the multiverse concept or the anthropic principle, which purport to explain why our particular universe has certain physical parameters. These models presume that we are stuck, conceptually."...

"The question of how we decide whether our theories are correct or wrong or falsifiable has a philosophical aspect. But in the absence of empirical data, can we really judge the validity of a theory? Perhaps. Can philosophy by itself resolve such an ontological quandary? I doubt it."

[Regarding "spacetime"] "Our model of space-time, as amended by Einstein, is extremely useful, but perhaps it is not fundamental... We do not really experience space-time; it’s a model.

Quote:

In the book, Hawking indicates that space expansion is not subject to the limitation of the speed of light.

At first glance, Oris, I thought (since you chose the word "indicates"), that you might be taking this to be a presentation of "fact." But, I was impressed to see that you are not:

Quote:

The speed of inflation after Big Bang is speculated to be million times faster than light.

It is indeed an unproven "speculation," one which was made as a means of reaching a desired goal. Such "speculation" is rampant in modern physics. Many physicists frown upon it. For example:

Quote:

In the early 1970s, David J. Gross exposed the hidden structure of the atomic nucleus. In 2004, he shared the Nobel Prize in Physics...And today he struggles mightily to describe the basic forces of nature at the Planck scale...

Gross characterizes theoretical physics as rife with esoteric speculations, a strange superposition of practical robustness and theoretical confusion. He has problems with the popularizing of “multiverses” and “landscapes” of infinite worlds, which are held up as emblematic of physical reality. Sometimes, he says, science is just plain stuck until new data, or a revolutionary idea, busts the status quo....

Gross: "There are frustrating theoretical problems in quantum field theory that demand solutions, but the string theory “landscape” of 10*500 solutions does not make sense to me. Neither does the multiverse concept or the anthropic principle, which purport to explain why our particular universe has certain physical parameters. These models presume that we are stuck, conceptually."...

"The question of how we decide whether our theories are correct or wrong or falsifiable has a philosophical aspect. But in the absence of empirical data, can we really judge the validity of a theory? Perhaps. Can philosophy by itself resolve such an ontological quandary? I doubt it."

[Regarding "spacetime"] "Our model of space-time, as amended by Einstein, is extremely useful, but perhaps it is not fundamental... We do not really experience space-time; it’s a model.

https://www.quantamagazine.org/20130524-waiting-for-the-revolution/

NASA's COBE (launched in 1992) and WMAP (launched in 2001) have confirmed that inflation did happen. That is why Hawking indicates the fact.

The very results hailed this year as demonstrating a consequence of inflationary models of the universe – and therefore pointing to the existence of multiverses – now seem to do the exact opposite. If the results can be trusted at all, they now suggest inflation is wrong, raising the possibility of cyclic universes that existed before the big bang.

I talked to Steinhardt about cosmology and in particular inflation, an idea that he helped refine in the early 1980s. Inflation holds that immediately after the big bang, our universe underwent an almost unimaginably explosive, faster-than-light growth spurt. Lately, Steinhardt has been criticizing inflation and related ideas, notably multiverses, in unusually blunt terms....

"Scientific ideas should be simple, explanatory, predictive. The inflationary multiverse as currently understood appears to have none of those properties.

On the one hand, mounting observational evidence gathered over the last 30 years supports what we thought were the predictions of inflationary theory based on our understanding prior to 1983. The irony is that our understanding of inflation has changed dramatically. We no longer believe that inflation makes any of those predictions so that none of the magnificent observations made over the last 30 years can be viewed as supporting inflation."

"As just explained, it is not possible to find evidence to support or refute inflation because an inflationary multiverse includes patches with cosmic gravitational waves and without them. So I must reinterpret your question to mean: could the BICEP2 observations yet turn out to be evidence of primordial gravitational waves, as the experimental team originally claimed.

No. The BICEP2 observations have been completed and published...by the standard rules of scientific methodology, there can be no claim by BICEP2 of detecting primordial gravitational waves (an alternative hypothesis).

The deeper problem is that once inflation starts, it doesn’t end the way these simplistic calculations suggest,” he says. “Instead, due to quantum physics it leads to a multiverse where the universe breaks up into an infinite number of patches. The patches explore all conceivable properties as you go from patch to patch. So that means it doesn’t make any sense to say what inflation predicts, except to say it predicts everything. If it’s physically possible, then it happens in the multiverse someplace. I hope we can return to good scientific practice."

The basic proposition is that, theoretically at least, a space ship can go 13.7 billion light years in 23 years and never travel faster than the speed of light.

Does anybody see a problem with this claim? Isn't there "something" inconsistent here?

What assumptions underlie such a claim? How would carrying those same assumptions over to other areas of physics mandate a reassessment of our "knowledge" in those other areas?

That is why Hawking indicates the fact.

Quote:

That is why Hawking indicates the fact.

On what basis can Hawking, or anybody else, say that is a "fact?" This isn't the question I was asking, but it has now come up and may be worth looking at, Oris.

Basically, the reasoning starts with "if A, then B." For example:

A= If there was inflation
B = then we would expect to see gravitational waves.

OK, now what? We go on the conclusion: We do see gravitational waves (B), therefore A is true.

This is a formal logical fallacy, sometimes called the fallacy of affirming the consequent. The form is "If A, then B; B therefore A."

You might just as well argue something like: If invisible elephants existed (A), then we would not see them (B). We do not see invisible elephants (B), therefore invisible elephants exist (A).

A second example: If God stood above the earth and took a piss (A), then the ground would get wet (B): the ground is wet (B), therefore God took a piss above the earth (A).

Can A now be deemed to be a "fact?"

Since we don!ˉt have a complete quantum theory of gravity, the detailsare still being worked out, and physicists aren!ˉt sure exactly how inflation happened. Butaccording to the theory, the expansion caused by inflation would not be completely uniform, as predicted by the traditional big bang picture. These irregularities would produce minuscule variations in the temperature of the CMBR in different directions. The variations are too small to have been observed in the 1960s, but they were first discovered in 1992 by NASA's COBE satellite, and later measured by its successor, the WMAP satellite, launched in 2001. As a result, we are now confident that inflation really did happen.

we are now confident that inflation really did happen. (Hawking)

String cosmology is a part of theoretical physics that has become detached from experiments. If the title Physics on the Fringe fits the natural philosophers, the same title also fits the string cosmologists. (Freeman Dyson)

String theory became a postmodernist monstrosity, lumbering forward on self-provided momentum without ever receiving the pruning from experimental verification that physics demands. (Garet Lisi)

I simply can’t imagine why any sane person would imagine, discuss, or mention, except insultingly, the concept of a theory of everything. It's a stupidity. (Sheldon Lee Glashow)

Anyway, Oris, it seems to me that all this talk about "inflation" for an infinitesimal amount of time doesn't relate to the question I asked at all. The question was:

Quote:

The basic proposition is that, theoretically at least, a space ship can go 13.7 billion light years in 23 years and never travel faster than the speed of light.

Does anybody see a problem with this claim? Isn't there "something" inconsistent here?

What assumptions underlie such a claim? How would carrying those same assumptions over to other areas of physics mandate a reassessment of our "knowledge" in those other areas?

Yes, it does. Because it concerns how space can be distorted under some conditions.

The basic proposition is that, theoretically at least, a space ship can go 13.7 billion light years in 23 years and never travel faster than the speed of light. Isn't there "something" inconsistent here?

Quote:

Yes, it does. Because it concerns how space can be distorted under some conditions.

Well, assuming that space can be distorted, how is that applicable to the question? Which was:

Quote:

The basic proposition is that, theoretically at least, a space ship can go 13.7 billion light years in 23 years and never travel faster than the speed of light. Isn't there "something" inconsistent here?

Assuming space can "expand" at thousands of times the speed of light, how would that get you "across the universe" faster? Wouldn't it just make the trip all that much slower, rather than faster?

Three steps to get faster:

(1) To make clear the mechanism of space expansion;
(2) Use the mechanism to contract the space in front of the ship;
(3) Confirm the safety of the new technique of space contraction and put it to actual practice to make the ship move faster.

Oris, I'm really just trying to get you to think critically about the claim being made here. I might not bother if I didn't know from many other posts you've made that you are a critical thinker.

I can't say the same for Max. He seems to think pointing to irrelevant math formulas answers the question being asked. I would suggest that merely saying "space can expand/contract" doesn't really address the question either. Beyond that, I see the claim that space can contract and/or expand as being a very problematic proposition to begin with.

If you're so confident about the movement of the space ship, tell me why speed of light is confined to 299792.458 km/sec and cannot be surpassed?