FYI: Can Anything Move Faster Than Light?

Longer is not faster.....

If it could, then it couldn't be assessed as actually doing so, for light and its speed is the fastest transmission system with which anything could ever be measured.

Comment 1: What is printed above IS the whole article, aside from an obligatory picture of a Star Trek 'Enterprise' class space ship.

Comment 2: I 'get' the idea that a region of space itself can expand at an extremely high speed, and while the speed of light within that region of space is locally measured as 'c', to an observer far away the net redshift of an object within that region could be faster than the speed of light. (It seems a bit impossible to me, but I'll accept the argument as it stands.)

What they never seem to explain is how that region of space got accelerated to that v>c speed. 'The Big Bang' or 'Inflation' are words that describe what got the universe going, expanding ever outward. But naming a thing isn't the same as describing the physical mechanism. HOW could an explosion accelerate something that fast? Or conversely, what IS 'Inflation' that makes it suddenly cause the universe to expand by many orders of magnitude, then just as suddenly stop, while still causing the galaxies to fly apart? I.e., if inflation was just an expansion of space why didn't the universe stay at that same size once the inflationary period ended?

It reminds me of the famous Sidney Harris cartoon:

The mechanism for the increase in expansion is believed to be driven by Dark Energy.

If you look back at the history of the universe, its expansion rate has not been constant.

'....expansion is believed to be driven by Dark Energy....'

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A circuitous explanation, don't you think?

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It sounds as if the following is being said (without a smirk):

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"This phenomena was previously difficult to explain, but we now believe it is caused by this theoretical stuff we conjured specifically as the explanation for the phenomena".

Exactly. I've read about Dark Energy quite a bit. Calling it 'Dark Energy' still doesn't explain how this can yield faster than light speeds. I know that some theoreticians equate Dark Energy with Einstein's Cosmological Constant - but I don't ever remember reading where Einstein said that certain values of the Cosmological Constant would yield a universe that expanded faster than the speed of light. (IIRC, he pretty much said that physical matter cannot exceed 'c', ever.)

Why, or actually, how does this happen? What is the physical mechanism? Even if they don't know what it is, they should have some better explanation that to say 'it makes it expand real fast'. My junior year Classical Mechanics professor would have called this 'hand waving'.

Well, it is a bit of a theoretical Hail Mary, but it is the best explanation we have so far.

However, to dismiss it out right implies that you must have a better alternate theory in mind and cause to support it. For me, I will hang my hat on dark energy until it is either proven wrong or some more accepted explanation comes along.

As you know, science is about observing something, then formulating a hypothesis to support that observation. So, yes, you do need to conjure an explanation, but using an educated and scientific approach.

Usbport,

First, the idea of faster than light speeds is a little misleading, but basically space expands and can expand at varying rates. It is very well accepted that there was an inflationary period to the early universe and the rate of expansion was extraordinary.

The inflationary period began at about 10^-36 seconds after T=0. Prior to that point all four fundamental forces were unified and the Strong Force separated at this time in the universe's birth. The symmetry break point of the Strong Force was the trigger for inflation.

Inflationary period ends at 10^-32 seconds and the universe had expanded from a pea sized grain to something close to the present observable size. That is greater than 10²⁰ increase in the observable radius in a cosmic wink.

We are pretty sure that this occurred and it satisfies both the Horizon Problem (homogeneous background microwave radiation) and the universe's Flatness Problem (whether the universe's expansion is open, closed, or flat).

The inflationary period is an example of space expanding faster than energy could transfer from one region to another (Horizon Problem). Obviously, thermal equilibrium to the extent that the microwave background radiation has reached (~.01%) would not be possible with the size of the universe at the post inflationary period because photons could not have transversed the size of the universe in 10^-32 seconds. Put anther way, how could the universe cool isotropicly if one end of the universe could not communicate with the other?

Extrapolating backward 14 billion years (age of the universe) the current expansion rate would have yielded a universe about 25 billion light years in diameter. There is no way the universe had cooled homogeneously if the universe was that size. The universe must have been smaller.

The only way we could get an isotropic cosmic background radiation is if the universe initiated as a very small volume where conditions were the same within that volume and that would have to be the pre-inflationary period.

We do know with a very high degree of certainty that this happened. However, the principles behind dark energy are very much a mystery. The latest theory says that gravitons may be the mitigating particle that keeps inflation in check.

Quantum physics predicts vacuum energy, but the predicted value for that energy is far too big to explain why the universe is currently not ripping apart. It is postulated that gravitons are "soaking" up that excess energy. I guess if we can peel back more layers of the onion with regard to understanding gravity we might determine if gravitons really do exist and how they fit in the grand scheme of things.

Unfortunately, there are many more unanswered questions than there are answers on the subject, but I just see that as the start of a very wondrous human journey of discovery at our feet. Therefore I do not quite share your pragmatism about the subject and reject these dark energy theories just because I do not understand them.

I have to give some credit to minds far sharper and more educated than mine. So, I do my best to just try to understand the questions and not worry about not having all the answers.

Yes, I appreciate that. Fascinating stuff, and it sums up a lot of what I've read.

But what IS the Inflaton Field? No one seems to be able to say. It's purpose is to describe the phenomena that we see. But without a physical basis that ties the 'field' to physical particles or energies, it's just another 'then a miracle occurs' step in cosmology. It's really no different than Copernicus using more epicycles and deferents to better-describe the positions of the planets than Ptolemy did. It reproduced the phenomenon better, but had no physical meaning.

They try to dress it up with words like 'driven by a negative-pressure vacuum energy density' -- which is caused by...? It started because...? It ended because...? It won't suddenly undo itself because...?

No, I reject the idea that I 'have to have a better theory in mind'. I recognize that this theory has made some predictions that have been confirmed. But (ahem) so did Copernicus. I reserve the right to be a skeptic.

The Higgs Boson, proposed in 1964, was key to the standard model of quantum mechanics. It's what 'gives' some particles the property of mass. It was tentatively confirmed to exist earlier this year. Inflation was proposed in 1980. So (making an unfair analogy) I suppose I need to wait until 2030 for someone to find the 'inflaton' particle and explain the cause of inflation, etc.

Describing the inflation field or vacuum energy is a little more than I have time to get into here. It is not "a miracle happens here" moment, but grounded on physics.

However, we are treading on a lot of theoretical ice. So expect the theories and models to be adjusted as we learn more. I think that the Standard Model is pretty solid. I don't expect some discovery next week that will tear the world down (would be exciting if it happened). I expect discoveries that continue to support the model with some modifications along the way.

I think a lot of your questions would be answered better with some research on quantum physics as this domain is where the nut of vacuum energy is.

'...However, to dismiss it out right implies that you must have a better alternate theory in mind and cause to support it.....'

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Um...well, no. Twice.

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First, I'm not dismissing it outright. I would say it possible explanation that has been well vetted theoretically.

I was just balking at 'expansion is believed to be driven by Dark Energy'.

That, to me, suggests far more certainty that reasonably should be allotted to an explanation that relies a completely new proposed 'something' that hasn't been needed for past observed anomalies...and that this 'something' is proposed to behave in a way for which we have no observational evidence of anything else behaving similarly.

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When we add in the fact that this heretofore unobserved or even suspected stuff needs to make up the vast majority of the mass/energy of the universe, it makes me thing we might be too confident about some of our interpretations of the data.

Perhaps we are reading the CMB tea leaves erroneously?

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Second, if I were rejecting it outright, that does not require a competing explanation.

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I'm sure you can think of some cases when you could reject a proposed explanation outright without putting forth a better explanation. You don't have to know the correct answer to know that certain answers are not correct. (Once again, that is not my position on Dark Energy/ Expansion.... )

I really do not see a conflict. Dark energy is the best candidate so far for the driver of inflation. However, it is not pulled totally out of a vacuum (excuse the pun). There is a significant amount of evidence to suggest it really exists, we just don't know much about it at this stage.

Many things were once unobserved and later proven to be true. That is the nature of science and hypothesis.

We could always be wrong about our understanding of the universe, but odds are we have a solid foundation. What we understand is incomplete, but these theories are not simply just right or wrong. There is a lot of gray shades in between. It's a bit like a giant puzzle. We have a lot of pieces already there and you can see the overall picture, but there are some blank spots, too.

The thing with science is we really like to dot all the 'i's and cross all the 't's. The devil's in the details.

When you put it that way....

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It is easy to see we are on the same page (even without crossing my 'i's .....or dotting my 't's).

AH, your response has had me thinking.

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I have another 'Hail Mary' class possible explanation to compete with Dark Energy.

It is not nearly as well developed as Dark Energy. In fact, it isn't very well developed at all, so bear with me. It is probably best to keep a brainstorming frame of mind at this point....

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Let your guard down for a moment and suppose that a civilization of Kardashev class IV or V felt a responsibility to leave a message (explaining why we were soon to be greatly inconvenienced, or perhaps how to contact them or visit them in the universe/dimension they had departed to) that was both subtle and available everywhere (in this dimension/universe).

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Subtle, because they didn't want the message discovered before civilizations had matured sufficiently to cast away their infantile behaviors, lest they worship the message, or use it to obliterate themselves.

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Available everywhere, because of the uncertainty with where advanced civilizations might arise.

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Wouldn't a great vehicle for a message like that be unmistakable variations in observations of distant past from what the study of all observations would predict?

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"....Okay, and then lets make it look like suddenly everything accelerated rapidly away from everything else....they will have to realize they have stumbled upon something intentional. An major event like that with no known cause, will be unmistakable...."

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Perhaps working up theories on expansion and dark matter, is a bit like working hard on previously unknown weathering phenomena upon discovering the Rosetta Stone....weird weather patterns have obviously shaped this stone into something that looks remarkable intentional....

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...Is anyone trying to decode the unexpected variations in the CMB?

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Okay, once you have had time to stop guffawing, consider that this idea isn't really that far off from what SETI keeps an eye out for..... just on a scale that seems nearly impossible to us.

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SETI searches among the electromagnetic signals for signals that they believe would not originate from the universe (with the laws based on past observations) without the influence of something intentional.

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The variations that are unexplainable without developing a novel stuff as the cause certainly fits a similar definition.

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Okay, ridicule away.

Actually, the slight permeations in the CMB support M-Theory or String Theory. M-Theory predicts very tiny variations and that is exactly what we are seeing.

I'd have to look up the exact reason for that prediction as I have forgotten.

Hmmm.

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M-theory has its origins in the 1990's, right? The fluctuations in CMB were noticed somewhere back in the 1960's, right?

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There isn't really a need to look up the exact reason for that 'prediction', unless causality and the forward progression of time are also up for debate.

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I don't really think it is fair to call it a 'prediction', considering the timeline. How about 'post-diction'... that way it still gets to be mentioned and sound impressive.

Nope.

It wasn't until the last 10 years that the variations in CMB were confirmed. We are still doing more detailed mapping to refine the variations, but it looks like it is about .01%.

A recent study shows another variation that has not been confirmed that may still be a statistical fluke, but indicates a region in space where CMB is lower than expected.

Up until recently the CMB measurements were not able to resolve any variations at all. A 10-year study called WMAP was just completed and published last year and discovered the variations.

'Nope.'

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I'll see your 'Nope', and raise you a 'Close, but still Nope'

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As far as I can find, May 1995 is the dawn of M-Theory.

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Anisotropy in the CMB was detected with instruments on weather balloons in 1981 and later with instruments lofted by sounding rockets in 1987.

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In 1992 scientists using data from COBE announced confirming CMBE anisotropy with the most detailed measurements at the time.

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I realize more detailed measurements have been made, but variations in the CMB were suspected, then measured, then confirmed at least several years before the announcement of M-theory.

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One of the weaknesses of M-theory is its as-of-yet nonexistent predictive powers.

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I know you believe all times exist at once, and that there is no privileged perspective....but for the purposes of measuring the utility of a theory by evaluating its predictive power, the prediction still must come before (in time) the measurement (or at least knowledge of the measurement) of the event to qualify as valid.....even if the theory suggest an alternative.

I am out of town, so I really do not have access to my library to cross check. However, my understanding is that there is a link with CMB variation and predictions made of the anisotropic nature of the CMB via String Theory or its modern derivative, M-Theory.

Does not seem to matter to me that variations were suspected or even detected in the CMB prior to M-Theory. Actually, String Theory, a precursor to M-Theory, goes back before 1970.

I will also not claim that anisotropic CMB is proof of any theory (String or M). It simply interesting to me that the prediction exists.

It interests me too.

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I know that if you say M-theory or even one of the non-consolidated string theories has a major prediction under it belt, chances are pretty good that is does.

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My searches haven't turned up anything to satisfy my curiosity, so I've registered my protest of disbelief and now I'll have to wait till you are back in your home.

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I hope your trip is enjoyable. Safe travels.

According to Brian Greene, String theory started in 1968. More than 1000 papers on string theory were written by 1986. String theory predicts super particle partners. ST allows for fractionally charged particles, but none have been found. A challenge for ST is to determine if neutrinos are massless and to explain what the value of the cosmological constant is.

Hmmm....

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'...String theory predicts super particle partners...'

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Of which, exactly none have yet been found/confirmed.

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'....ST allows for fractionally charged particles,...'

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'....but none have been found......'

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You beat me to it.

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'.....A challenge for ST is to determine if neutrinos are massless and to explain what the value of the cosmological constant is......'

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Those are noble goals, and I will be impressed with whomever topples those challenges.

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The debate was originally about M-theory which although it is a joining of string theories, did not exist before 1995.

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Given that even going back another 30 years, it seems difficult to find an instance where any of the varied string theories has demonstrated utility via a confirmed prediciton.....I'm willing to let the argument slip from just M-theory to the encompass the whole of string theory.

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Are there any solid examples of confirmed predictions that can be credited to any of the thousands of papers written on String theory?

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I hope I'm on the wrong side of this debate.

I may have misspoke when I used the term M-Theory, but my reason was to try to be as current with the theories as possible. M-Theory is more or less the reigning theory today that is built upon String Theory.

So, when using M-Theory I am also embracing the theories it was built upon.

Fair enough.

So there must be examples of phenomena confirmed to have been predicted somewhere in the thousands of papers written about String Theory in the last 50 years....right?

Let me look that up when I return.

the universe itself will eventually outpace the speed of light.

Actually, that happened a long time ago. It is what accounts for the size of the visible universe.

Einstein's theory that nothing can travel faster than the speed of light in a vacuum still holds true, because space itself is stretching, and space is nothing.

His theory says that nothing with mass can exceed c. Space is NOT nothing. Every cubic centimeter of space contains all the laws of physics, including the value of c.

Yes. Professor Bright can.