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In this month's Discover, you'll find a brand-new column written by me. About the multiverse this month. Suggestions for future topics?
Ripu Jain's profile photoSatyr Icon's profile photoAmos Zeeberg's profile photoSean Carroll's profile photo
Talking about the End of the Universe, maybe get / ask +John Baez why he didn't include the Big Rip Theory in his End of the Universe Page? :)

Top of the page says January 2011, so Big Rip Theory was supported by some evidence. But bottom of page suggests it is a chapter to his book, published circa 2004. So maybe including the Big Rip theory on the page may be incongruous with already published book? When Big Rip Theory wasn't as established back then?

P.s. Hope this isn't off topic or inappropriate.
the link betwin quantic physic and macro physic(general relativity) excuse my english i'm little new be french boy ! :)
I'd like an explanation of quantum mechanics and a good explanation why physicists prefer the Copenhagen interpretation (if that's even true at this point!). Also, if you don't subscribe to the Copenhagen interpretation, which alternative do you prefer?

I guess for accurate topic suggestions, I should know what you are actually specialized in ;)
Current state of thought on extent of the entire universe (our bubble) beyond the visible/time horizon. I think Guth has written something like "at least 10**24" with certain assumptions about inflation. Do you think the observed laws/constants in our bubble extend to the "edge", whatever that might mean? is our bubble likely to be a true de Sitter space?
Explain why people shouldn't try to form their own physics opinions, but instead accept the judgements of expert physicists, but they should try to form their own opinions on economic policy, and not just accept expert opinion there.
+Robin Hanson Don't you think that is a bit of an obsucre question? The easiest answer is probably because physicists are scientists and the general public is not. If science (any science) could be done by everyone, it wouldn't need x years of study.

If you read a popular science book, you might understand the surface workings of a topic, as in, you can say "relitivity is this and Einstein explained it that way", but that doesn't mean you are now able to go and conduct an experiment, because you haven't the skills to do so.

Economy on the other hand, is not a field that works with pretty much unmoveable measurements - it is often highly opinionated and based often enough on someone's best guestimation.
+Kitty Zschoche This is the basic central question of what sort of epistemological attitude to take toward different fields. One possible answer is indeed to claim that physicists know tons, but economists know nothing, so accept physicists without question but believe nothing economists tell you. I doubt Sean would agree with that answer, however.
+Robin Hanson I am not sure whether we are meant to interpret your question as "I think this is true so explain why it is" or as "Sean thinks this is true and I disagree so defend your opinion". If it is the former then it is pretty funny coming from an economist with his own interpretation of quantum theory.
I'm curious. As a physicist I'd like to know the context behind +Robin Hanson's assertion "people shouldn't try to form their own physics opinions, but instead accept the judgements of expert physicists".

Over the decades I have seen physics terminology hijacked by other fields. Eg the term "quantum" used to describe social science phenomena. Whilst that may lead to confusion when discussing quantum physics, physicists don't own a language, and the wary reader/audience has to determine contextually what is meant by quantum each time they hear it, or read it.

Then there are topics in physics which is too specialised, or too advanced, even for me, and I will hesitate to offer "authoritative" opinions. Instead I will delegate that to experts, or specialists in those niches. Eg Theoretical Physics ==> +John Baez.

However there is many many simpler topics in physics, or simpler aspects of advanced physics pretty much anybody can form an opinion on. Even economists. And all the grey area in between. So I think context is important here in what +Robin Hanson is referring to?
Folks, the usual conventional wisdom is that people should defer to physicists on physics, but should not defer to economists on economics. This asymmetry requires some justification. I'm suggesting that Sean either reject this conventional wisdom, or instead discuss what justifies it.
+Robin Hanson I'd object to that "conventional wisdom" you cite above. Simple concepts in economics I think I can grasp with little reading, But advanced topics I'd happily follow several economists opinions. That would save me maybe 6 months to years boning up on the advanced stuff. Same with medicine, or law, or ceramics, or history etc.

However +Robin Hanson your above comment suggests that many physicists, including +Sean Carroll have stated or supported what you label as "conventional wisdom" amongst physicists. Is there a link to where this is asserted by +Sean Carroll, or other physicists to support that allegation?
If I may jump in again, economics can probably be learned by book, even the complicated stuff. But physics can't so easily, at least not by everyone. Maybe that is why we have to trust physicists a little more.
We all have instincts about money, honed by years of functioning in an economy. In some sense we are all sort of lay economists. So it's not surprising that we might be able to form sensible opinions on economic matters with only a little bit of reading. We also, having lived in the macro world all our lives, have a pretty decent sense of "folk physics" and our opinion on things like the collision of billiard balls counts. But we have no experience of quantum or relativistic reality. Physicists devote years to gaining this experience through experiments and understanding it with mathematics. We can't directly experience these worlds, which is what makes becoming a physicist such a long and difficult and even problematic project. So it's not surprising that the opinion of someone who hasn't studied for years should be taken seriously by physicists.
Personally, I think in all areas of enquiry there is a certain body of well-informed consensus that it would be crazy to question and certain ideas that are more speculative and questionable. The ratio between the two varies from field to field, but both components are almost always there. For example, in physics, I am perfectly happy to accept that the available evidence strongly supports the standard model of particle physics, even though I have not done most of the calculations myself, because I am satisfied that the experts have the relevant skills to make that judgment. i am less happy to accept proclamations about the interpretation of quantum theory, even though quantum theory is a subject that those same physicists would claim to be experts on, because I am well-versed in the controversy and can see that people are making contradictory statements about it.

The problem is that the further removed from everyday experience a topic is, the harder it is for a layperson to judge which statements are part of a well informed consensus, and which are speculative. It does not help that physics currently has a culture of hyping up every minor development beyond belief, which makes it look like incredibly speculative things are established only to turn around and say the opposite the following week. In such an environment, it is not surprising that people take to questioning everything.

With economics, I think people have the idea that they understand what is going on as much as the experts because it is closely related to a thing they deal with every day, i.e. money. It is not too different from something like music, which everyone has an opinion on because they hear it every day. You would not believe the number of times I have heard people say that music appreciation is completely subjective and that there is no such thing as objectively 'good' or 'bad' music (despite the fact that the existence of Celine Dion directly confirms the existence of the latter). They fail to realize that there can be objective standards relative to a particular musical vocabulary, and that everyone has such a vocabulary that is conditioned by their prior experience. Relative to a vocabulary, you can establish objective criteria of excellence. Similarly, people do not realize the extent to which their views on economics are conditioned on personal experience, and that people who have studied the subject in depth may have a better informed view.
It depends which multiverse you are talking about: the quantum mechanical one in many worlds interpretation, the one from cosmological inflation, or Max Tegmark's crazy one in which every possible mathematical structure represents a "reality". The answers are: no, I suspect no, but I'd have to ask a cosmologist and yes (by definition). The main point is that, in the first two multiverses, possibilities are still constrained by the laws of physics and by the initial conditions, and these certainly do not contain every logical possibility.
+Satyr Icon - there are all sorts of crazy theories people have made up for the end of the universe, like the Big Rip, the possibility of colliding with another universe (in the braneworld scenarios), Penrose's idea that the end of our universe is the Big Bang for the next universe, and so on. One of them may be right, but there's essentially no evidence for any of them, so I didn't consider them in my page on the end of the universe. I stuck with physics that's well-established.

Of course surprises are possible, indeed likely over these long time-scales.
I'm particularly interested in energy issues. These are more mundane than the sorts of things you usually write about in that they are about things more or less the same size as us. But I think there's a lot to talk about.

The earth regularly receives a certain amount of energy from the sun in the form of high frequency photons. Some of it is reflected; some is radiated away as heat; some drives the weather; some drives living organisms; some is stored as fossil fuels; etc (We are rapidly balancing the fossil fuels books.)

We live on the degradation of energy from usable to not usable. A question I'd like to see looked into is in what ways is energy used as it degrades. Some of it drives the weather, including oceans currents. Some of it drives life. Some of it just heats the earth's substance and gets slowly radiated back. The most interesting category is the energy that is used to drive life. How is that use divided up? What work is being done, e.g., in moving organisms around vs. building organism structures, etc. What do we know about unexploited niches in which energy is available but is not made use of biologically. What prevents biology from using those resources.

I know those are really big and complex questions. But if you are interested I would very much like to see an initial stab at it.
Russ, that's a good potential column topic. I did cover it in a chapter of From Eternity to Here, but it could be more widely appreciated. (Not that you can say very much in a 1500 word column.)
Sean, Are you talking about the second half of Chapter 9? One way of looking at what I'm asking for is the next level of detail. As you say though, 1,500 words doesn't give you much room.

I also like the previous suggestion. I'd like to understand Noether's theorem. Everyone has an intuitive understanding of what symmetry is. But most of us (including me) don't understand why it's such a big deal in physics. How does a symmetry get you to a conservation law.
Chapter 9, yes. Sadly these Discover columns are not going to be the place to go for more details...
topic suggestion:
- current state of LHC, whats next for it, what next big experiment proposals are out there after LHC.
- white holes: fantasy or theoretically possible?
- your comments on this video: Imagining the Tenth Dimension part 1 of 2
+John Baez thank you for your response. Sorry I didn't see it earlier from the flood of cutesy animal / lolcat pics on my stream!

I must admit your answer did come as a bit of a surprise to me. I thought the Big Rip was proposed by other physicists. Both theoretical and mathematical? And I thought it gained popularity soon after the discovery of the increase in acceleration of the expansion of the observable universe? Anyway I respect your opinion. Mostly because the maths is beyond me :)

One thing that does bother me. With regards to current cosmological theories, eg the Big Bang theory, theories about the large scale structure of the universe etc. Surely if we have to create exotic materials such as Dark Matter, and Dark Energy with even more bizarre properties, just so we can account for 96% of the missing mass then surely that's a call for going back to the drawing board with all of our 'working theories' about the structure, history, and age of the universe? I mean, if observations alone only account for 4% of the mass, the rest, 96%, we have to pretty much add as fudge factor just so the observations allow the theories (Big Bang, accelerating expansion of the universe, etc etc) to hold! Doesn't that say more about those theories?

Example: If I was doing a benchtop experiment to test a hypothesis about the theory, and it turned out my theories didn't account for 96% of the mass, I'd seriously consider tossing the theory and start from scratch! ?

Maybe the errors are in the observations? Or maybe we should revisit the WIMPS vs MACHOS dilemma? But whatever we have to do, I am finding a 96% 2,400% uncertainty rather challenging :)

Of course, anybody else who wants to chime in is welcome. And +Sean Carroll, if you feel I should continue this elsewhere please let me know. Thanks.
+Sean Carroll Maybe you could do a regular feature on the blog where you expound further upon what you put into the mag column. You could put a call-out somewhere in the column -- including a handy shortened URL -- pointing people to the blog to read more of the details online.
Might be fun to try. It's hard to do if the column isn't accessible online right away; people who just read the blog would be baffled.
+Sean Carroll Could write the column and blog post at the same time, but hold the blog post until the column goes up on the site. I can work with you on when that'll happen [do the same w +Carl Zimmer].
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