The best explanations of cosmic inflation are in cartoon form




Unfortunately stories are coming out casting doubt that the discovery is discovering what it claims to discover.

Which doesn't mean they're wrong.. just that it's going to take even more discoveries to explain things more fully.


Well, that's a little deflating.


Here's another good one, same topic ...


"Big physics news is often difficult to explain, which, sadly, means it doesn't get explained very well."

Albert Einstein said that if you can't explain what you know so a bar maid understands it, you don't know it.


An old mathematics joke

Two mathematicians were having dinner in a restaurant, arguing about the average mathematical knowledge of the American public. One mathematician claimed that this average was woefully inadequate, the other maintained that it was surprisingly high.
"I'll tell you what," said the cynic. "Ask that waitress a simple math question. If she gets it right, I'll pick up dinner. If not, you do."
He then excused himself to visit the men's room, and the other called the waitress over.
"When my friend returns," he told her, "I'm going to ask you a question, and I want you to respond 'one third x cubed.' There's twenty bucks in it for you." She agreed.
The cynic returned from the bathroom and called the waitress over. "The food was wonderful, thank you," the mathematician started. "Incidentally, do you know what the integral of x squared is?"
The waitress looked pensive, almost pained. She looked around the room, at her feet, made gurgling noises, and finally said, "Um, one third x cubed?"
So the cynic paid the check. The waitress wheeled around, walked a few paces away, looked back at the two men, and muttered under her breath, " a constant."


Scientific American observes that the experiments point to a specifc kind of inflation, and rules out other schemes.

The BICEP2 data would eliminate about 90% of inflationary models, Andrei Linde, a cosmologist at Stanford University in California, told a packed auditorium at MIT the day after the BICEP2 announcement (see picture). Many of those models do not produce gravitational waves at detectable levels, said Linde, who is one of the founders of inflation theory.

But he said that the findings would agree remarkably well with ‘chaotic inflation’, a simple version of inflation Linde developed 30 years ago. In Linde's model, inflation never completely ends, stopping only in limited pockets of space, while continuing with its exponential expansion elsewhere. Chaotic inflation would produce not just our Universe but a multiverse containing many pocket universes, each with its own laws of physics, an idea that critics say would be untestable.

We must be careful not to oversimpify.


"For every complex problem there is an answer that is clear, simple, and wrong."
-H. L. Mencken


Here's what I don't get. The further out we look, we see objects (galaxies and earlier and earlier galaxies) moving away from us faster and faster, i.e. red shifted more and more. But these things are in the PAST. So when you look at something in the most distant past (14 billion years) and it is moving away from you faster than things 13 billion years ago, and that stuff faster than things 1 billion years ago... That means that things in the past moved faster than things in the present. Or, in other words, that things were FASTER in the PAST and SLOWER RIGHT NOW.

So why does everybody say the universe is not only expanding, but accelerating? If it's going faster in the past and therefore slower now, then how can you say that? It's DEcelerating, not accelerating.

Anyone care to enlighten me?


I'm woefully unqualified --so here goes...

It's a matter of perspective. What I can grasp (not having the math skills needed) is the Rubber Sheet model explanation. Which is explained on the linked site thus:

We can imagine galaxies are like balls sitting on a rubber sheet which represents
space. If we stretch the sheet, the balls move apart. Balls which are close
together will only move apart slowly. Balls which are widely separated will seem
to move apart very quickly.

People living on any one of the balls will see their own ball as stationary.
They will see nearby balls moving away slowly and they will see distant balls moving
away quickly. Very distant balls (beyond the horizon) can be moving away faster
than the speed of light, but the people cannot see them - locally in their own part
of the universe nothing is travelling faster than the speed of light.

What I get from this is that the redshifted light is due to the expansion of the space-time fabric between observer (us) and subject (far flung celestial fuzzball). Greater distances = more stretching = more redshift.

Another way to look at it is with a driving example. I start a journey of 60 miles and travel at 60 miles per hour (as fast as the car is allowed to go). Should take an hour --but there's a catch. The road stretches as I drive. If the stretching is extreme my hour drive could take 13 billion years. If the road stretches at a rate greater than 60 miles per hour, I'll never reach my destination.

Anyone else? I'm not sure that really answers the question...


Actually, I found what you wrote enlightening because it had this mindbending effect on me that I found interesting. It makes me think of some stuff that I hope doesn't reduce your question with something boring, and conversely, some stuff that doesn't assume I have an answer, riddled with inscrutable jargon. It's just more questions really.

All I was going to say was something obvious; that I have noticed that if I see a plane in local airspace, it seems to have cleared the area of space that is visible to me quicker than an aeroplane thousands of feet higher.

The plane farther away is travelling faster than the nearer one that recently took off from the local airport, but it appears to be getting from A to B more slowly relative to my position. I guess also, along with the spatial context thing, because the light that creates the visual impression of the more distant plane took longer to reach me it is a light impression coming from the past?

I am seeing a light impression that does not accurately reflect that plane's real time to its occupants. Like if I am seeing the plane and looking at my watch and it says 3 o'clock, but the actual light impression of the plane I am seeing if I could somehow see through the walls magnified like it is Wonder Woman's plane - and with a comic book style magnified cutaway at that - could see a passenger looking at their watch, and their watch had been synchronized with mine before they left, it would be fractionally before 3 o'clock? Is there such a thing as objective time, or is it a kind of fallacy, or a tool we use that only works in a relatively localized field?

This doesn't mean the passenger existed before me does it? I mean, I just saw them earlier on, when we synchronized our watches. It just means the impression I am seeing of the plane they are in happened before I saw it?

The plane that is higher has a lot more space to appear to travel across which adds to the contextual illusion that it appears slower, or, to take more time?

Faster-than-light ships seem to be able to control the speed at which they travel right across the range of the visible-to-the-naked-eye spectrum and then outside of that. I think Time, or rather, our perception of it, is localized. Does this have to mean this effect has anything to do with a big bang, or necessarily expansion?

Our perception of density and objects' relative distances alter radically the further away they are from us, and of course red shift is based on the fact that the tools we are using to see that far away are representing those light impressions to us in the infra red spectrum. So it is already sort of out of our normal frame of perceptual reference, as are radio galaxies I guess?

Nope. Can't answer your question, sorry. Enjoyed thinking about it though.


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