We interrupt this tour through the solar system to bring you a special show to deal with one of our most complicated subjects: the big bang. Specifically, how it's possible that the universe could have expanded faster than the speed of light. The theory is called the inflationary theory, and the evidence is mounting to support it. Einstein said that nothing can move faster than the speed of light, and yet astronomers think the universe expanded from a microscopic spec to become larger than the solar system, in a fraction of a second.

<strong><a href="http://media.libsyn.com/media/astronomycast/AstroCast-071015.mp3">Episode 58: Inflation (17.0MB)</a></strong><br />&nbsp;<br />

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I understand 99% of what Pamela explained, but have a problem with ONE single analogy.

The Little kid walking 4 sidwalk-blocks per second, and then the builders adding sidewalk-blocks between him and the school....

She is adding him to the blocks.

BUT... that wouldn't make him go faster toward school. It would slow him from the perspective of the school. He would have 4 times as far to go if the sidewalk blocks were added in front of him even though he was still moving at the same speed.

A better analogy would be walking on a static mover, like at a theme-park and the people are walking 1 MPH on the mover, but the mover is moving at 1mph. So the person covers twice the distance in the same amount of time.

Nevermind... I just listened again. He was walking away from the school, and the block were added BEHIND him.

I get it now.

Tough episode!

I was interested in the comment about the expansion of the universe that it may have pockets of non uniformity, given that these are too far away to be observed, I think it was inferred that the expansion may not be linier.

This got me to thinking, we picture the universe as expanding from a single point out to a sphere. Is it at all possible that the universe is more like a running crack in a pane of glass? i.e. the crack (expanding) but continuing?

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“Life is not measured by the number of breaths we take, but by the moments that take our breath away”

The paradox is real, the expansion of space as an answer to this paradox is not. There are energy issues: If the space has increased, then the net gravimetric energy between two objects on either side of the expanded space has also increased, and where did this come from?

Builders adding blocks adds energy, just as an expanding loaf of bread requires energy from the oven. Inflation does not address this energy issue. This explanation for the size of the universe is thermodynamically bankrupt. It is as phony as perpetual motion, and should be summarily dismissed.

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jwj

If you always believe what you already know, you can't learn anything - Liz

Perhaps you are looking at it wrong.

Put a tiny marshmallow into a vacuum jar, and suck all the air out. The Marshmallow attempts to fill the entire volume.

There is no lost energy, no gained energy. All the same Marshmallow, just expanding.


That is to say... our universe has no container, so it is trying to fill an infinite volume with finite matter.

Wouldn't it require energy to suck out the air to create the vacuum?

It's the same physical marshmallow, but the properties of it's physical location have changed.

To force the air out of the jar...yes.

But space itself is already a vacuum.

If inflation is the expansion of space itself, and if you accept that a vacuum requires space (and time), then the jar isn't even really a vacuum, but something...else?

The 'expanding universe' explanation I've most often heard is that spacetime has its own intrinsic 'vacuum energy' or pressure that drives expansion; so as spacetime expands so does the amount of pressure--hence the accelerating universe. It all sounds pretty tidy, but I must confess inflation has always seemed just a little arbitrary. There is something about 'phase transitions' (like when water turns to ice) which sounds appealing as a way to explain the difference between inflation and expansion, that may also be related to the fundamental forces 'condensing' out of the grand unified force. (Think of the universe as frozen energy, cooling from its original hot-dense state. The universe as a giant popsicle!)

I've also heard the 'vacuum energy' of spacetime linked to the idea of 'virtual particles'. I'm sure others more knowledgeable than me can elucidate.

I haven't had a chance to download the cast yet so apologies if I'm off topic.

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If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

Hey Jerry

I thought about this a bit.

It seems science doesn't have a good handle on the properties of the universe prior to the planck epoch, save it was very hot and very dense. Could it be that the energy for everything that has happened to the universe since, was already there at the start?

To me, the idea of the universe condensing out of this unimaginably hot, dense, and energetic state has always appealed. If you compare the young universe to steam: steam doesn't require any energy added to condense into water...the 'steam' actually gives up energy to it's environment in the process, right? I think the technical term is 'exothermic phase transition'. To a lay man like myself, does this address your thermodynamic objection in any way? I still haven't listened to the podcast so I don't know if Fraser or Pamela have mentioned the idea already, apologies if they have.

Of course, the really big mystery would be how did the 'steam' get there in the first place?

For me, the 'expansion' of the universe and this idea of 'phase transition' are inextricably linked. Did one somehow cause the other... or each other? And then you have the 'arrow of time.' Its all wonderfully evocative to imagine when I look out at the night sky with my two little boys. (They already love to tell people they're made of Stardust, I think I'll get them to try Condensed Big Bang!)

Anyways... back to work for me...

__________________
If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

In the inflationary theory, matter, antimatter, and photons were produced by the energy of the false vacuum, which was released following the phase transition. All of these particles consist of positive energy. This energy, however, is exactly balanced by the negative gravitational energy of everything pulling on everything else. In other words, the total energy of the universe is zero!


there is no energy lol

your just imagining it

great episode really got the flatness problem over well

http://abyss.uoregon.edu/~js/ast123/lectures/lec17.html

Have enjoyed Astronomy cast for several months but not tempted til now to register and comment--for the purpose of asking: What caused inflation and what halted it? Dr. Gay's reference to "inflaton" particle as causing inflation floored me. I had thought inflation was the "intrinsic" rate of big bang expansion until slowed by emergence of "mass" and gravity, i.e. graviton. If "inflaton" caused inflation, what caused its decay? graviton? Are "inflaton" and graviton related? I'm afraid your Inflation explanation raises more questions than it answered. Why did inflation last 1-33 seconds? What happened to cause expansion to slow to "historic" rates.

Thanks for all the hard work.

Finally got some spare time to listen to the show--wow! Great work Fraser and Pamela. I was really excited to hear Pamela say that the observable universe is thought to be three or four percent of the entire universe; it's something I've wondered ever since I 'got' the size and shape of the observable universe and our place in it.

If Pamela says its three or four percent that's good enough for me. Does anyone know *how* we figured out that percentage?

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If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

I'm with you Stan--although I read the term 'inflaton' recently rather than hearing it first on the podcast. I'm still trying to 'get' the Higgs Boson, then along comes the Inflaton! So far I've decided the science of inflatons is a bit beyond me yet.

Even Wikipedia doesn't have a lot to say about it:

The inflaton is the generic name of the unidentified scalar field (and its associated particle) that may be responsible for an episode of inflation in the very early universe. According to inflation theory, the inflaton field provided the mechanism to drive a period of rapid expansion from 10−35 to 10−34 seconds after the initial expansion that formed the universe.

The inflaton field's lowest energy state may or may not be a zero energy state. This depends on the chosen potential energy density of the field. Prior to the expansion period, the inflaton field was at a higher energy state. Random quantum fluctuations triggered a phase transition whereby the inflaton field released its potential energy as matter and radiation as it settled to its lowest energy state. This action generated a repulsive force that drove the portion of the universe that is observable to us today to expand from approximately 10−50 metres in radius at 10−35 seconds to almost 1 metre in radius at 10−34 seconds.

I would love it if anyone had a nice simple explanation or link that describes what a 'scalar field' is?

__________________
If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

Hey Damian

That's the thing isn't it. I can go outside and kick the road and its like 'whoa! the earth is big', then I can look at the night sky and 'wow! look at all that...stuff'.

And then, 'where does it all come from?'... and it turns out it is all virtually from 'nothing'.

Or go the other way: the earth is made of atoms, atoms are made of quarks, quarks are made of what? Strings? Nothing?

Way better than any Star Trek episode!

Good link too.

__________________
If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

Hi Steve. The closest answer that I found is that cosmologists think that the minimum size of the total universe is some 133 billion light years radius. This gives a volume of around 10 billion billion cubic light years. The observable universe has a present radius of about 46 billion light years, giving a volume of about 400 thousand billion cubic light years. The observable volume is then about 4% of the whole.

One must remember though, that the observations are also compatible with an infinitely large universe, which makes the observable portion, well, zero %?

Hi Burt

Are the observations such that the entire universe is either

a: very large (and ours is 4%)
or
b: infinite

or is it just that the very large universe is the miniumum size?

The reason I ask is that the idea of 'infinity' makes my brain explode! I'd be happy to know the 4% deal is a 50/50 proposition.

There's a good show on the BBC World Service website where various experts debate infinity and I get the impression that infinity is a mathematical construct that can't actually exist anywhere in reality. Your example above is a good one: if the entire universe is infinite then the observable universe is 0% - and yet here we all are, and it is rather a lot of stuff! (Actually I'm not sure about the maths--is it 0% or just an 'infinitely' small % but not quite 0?)

I'm gonna buy 4% - at least I'll be able to sleep nights!

A Brief History of Infinity: Space and the Universe
http://news.bbc.co.uk/2/hi/programme...ve/5349064.stm

A Brief History of Infinity: Mathematics
http://news.bbc.co.uk/2/hi/programme...ve/5349364.stm

__________________
If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

Hi Steve.

Yea, infinite size doesn't really make sense, does it. I think present observation indicates that the universe is at least 25 times the size of the observable universe (which is then at most 4% of the total). The universe may possibly be millions of times larger than our observable patch, but no one knows just how BIG and we may never know.

Burt

as i understand it no one has any idea how big our ''bubble is beyond the observable universe.....tho i have heard much much larger estimates then 25 0/0...... one i liked i cant remember where from was that the observable universe was the size of a photon then the entire bubble was the size of the earth.....

but no one knows... (apart from douglas adams)

but to cut a long story short if the edge of the universe is receding from us faster than the speed of light then it is to us on any practical level unending

?

i love this stuff

lol