Please explain the statement "the big bang happened everywhere at once"

[phinds]

Yes, but I meant that if you look out far enough, don't you see things as they were in the past? So from the perspective of some observer, if you looked out far enough, wouldn't you eventually see space becoming infinitely compressed to a point where you can't see any further?

Yes that's correct, but it does not change the measure of distance so your example with the rule is ill-stated at best.

Because space was smaller, and the marks on the ruler that are further away from the observer from the perspective of the observer would start to appear closer and closer together, right? I'm not saying that the measurements are changing, but if there is a mile-long segment of the ruler far away from the observer with a length locally of one mile, to an observer far away won't it look smaller because space itself was smaller?

Yes, but again, I interpreted it as meaning that the size of the ruler shrank. I don't see what other meaningful interpretation can be put on your original statement.

It sounds to me like you understand what's happening but chose a poor way to describe it.

 

[jack476]

It sounds to me like you understand what's happening but chose a poor way to describe it.

Yea, that happens to me a lot. It's kind of a problem for me. Sorry :/

 

[dragoneyes001]

Do you know what a field is, what it means, and what it is not? An issue here on PF is naivete of space, time, dimensionality, proof, falisifiability. Many of our correspondents are un-read in the topic upon which they are commenting.

the same could have been said of the people proposing that the world was round and not the center of the universe by the scholars of the day before they tortured and imprisoned the detractors of those current beliefs. falsification is usually by people trying to protect their position not by people trying to ask about a subject. over history many advances in our current understanding of the sciences as well as advances in technology come from people outside of the very specialties they advanced because they brought fresh perspectives with them.

 

[Bandersnatch]

the same could have been said of the people proposing that the world was round and not the center of the universe by the scholars of the day before they tortured and imprisoned the detractors of those current beliefs. falsification is usually by people trying to protect their position not by people trying to ask about a subject. over history many advances in our current understanding of the sciences as well as advances in technology come from people outside of the very specialties they advanced because they brought fresh perspectives with them.

Say your car breaks down and a guy starts telling you it's the fault of the carburator being clogged, or the alternator outputting too high a voltage, and says he thinks he can fix it. However, when asked he can't explain what these parts are or do, nor point to where they are. In fact, you're pretty sure he called the radiator a fuel tank. Would you leave your car to the guy or ask a professional mechanic to fix it for you?

The myth of the outsider revolutionising a field is very tempting to fall for, as it feeds on the thirst for fame and glory every single one of us have harboured at some time in their lives. It's about being the underappreciated underdog that shows all those stuck-up arrogant eggheads that he was right and they were wrong (and gets all the girs/guys, presumably).

In reality, that never happens. All the "outsiders" that ended up changing the scientific paradigm weren't random people off the street, willy-nilly arranging words whose meaning they don't understand - they were all learned in the subject and knew what they were talking about. Yes, the fresh perspective is important, but that usually translates to people making major breakthroughs early in their careers - often in their twenties - simply as soon as they managed to absorb all the prerequisite knowledge.

As for being tortured for saying the Earth was round:
1.You're probably referring to the Catholic Church and Holy Inquisition - an organisation claiming access to infallible truths which is more or less the opposite of science.
2.Even they never did that. That the Earth was round was known among learned men at least since Eratosthenes. The moral of the story: ignorance is not a virtue and empty mind does not equal open mind.

 

[jack476]

the same could have been said of the people proposing that the world was round and not the center of the universe by the scholars of the day before they tortured and imprisoned the detractors of those current beliefs. falsification is usually by people trying to protect their position not by people trying to ask about a subject. over history many advances in our current understanding of the sciences as well as advances in technology come from people outside of the very specialties they advanced because they brought fresh perspectives with them.

http://rationalwiki.org/wiki/Galileo_gambit

Now, that's a pretty dangerous argument to make. Yes, people need to be cautious of credentialism and experts should be willing to engage with the perspectives and knowledge of non-experts, like scientists who need to consult with engineers when putting together equipment. There is also some truth to the argument that some important historical discoveries were made by non-experts in science. However, that has more to do with the fact that science as a profession didn't really exist until the 19th century century and it was by necessity an amateur-ish pursuit.

Furthermore, while many famous scientists from history were not "experts", that does not mean they were not educated or knowledgeable, it just meant that they did not have as much to go on as scientists do today. They worked just as hard and just as diligently, and that is why they were ultimately vindicated, not because they were rebels showing up the tyranny of the establishment.

 

[dragoneyes001]

who said they did it to rebel? both examples were of the then educated refusing to accept any deviation from the current sciences as they saw it. yes the church was the culprit so to speak but at the time education was limited to people of the faith and strictly guarded to stay that way.

yes an incompetent in any field is still incompetent. yet doctors which undergo a lengthy education by trade are just as likely to be wrong about a problems cause as a Certified mechanic is even with ten times the amount of technology helping the diagnosis for the doctors. the difference is the doctor has a much better chance that his/her mistake will cost a life.not that a bad mechanic can't end up killing a driver too just less likely to.
specialization does not make a person infallible.
there is always the possibility that what's believed to be true today can be overturned tomorrow.
one of you is saying that scientific advancement truly only ages from the 19th century I beg to differ GREATLY! you'd have to completely ignore the advances in all the forms of building dating back thousands of years and all the native herbology worldwide plus all the other tools humanity developed long before the 19th century to actually believe that. yes you can say understanding the way the shape of a wing creates lift when it passes through the air helps with making planes but I'm pretty sure at the time of the Wright brs. none of those teams trying to be first to fly had that information and they still managed to get airborne.

 

[PeterDonis]

All, the sub-thread in the last few posts is getting off topic, and also getting close to being a discussion of philosophy, not physics. Please keep things on topic. Thanks!

 

[Monsterboy]

All, the sub-thread in the last few posts is getting off topic, and also getting close to being a discussion of philosophy, not physics. Please keep things on topic. Thanks!

The argument in last few posts started with my question , it had nothing to do with rebelling with established scientific knowledge or Galileo' gambit or whatever, it was just a simple question , anybody who lacks the patience to respond to questions asked by amateurs should refrain from answering.

 

[PeterDonis]

The argument in last few posts started with my question

Has your question been answered? phinds responded to it.

 

[Monsterboy]

Has your question been answered? phinds responded to it.

Phinds did say it is not very clear what space is , so there is no point asking more questions on it.

 

[William Donald]

I read a neat theory on how our universe is like a balloon; however it can save itself from popping by retracting back in. The theory went on how the universe expands from a small scale (big bangs) and contracts from a large scale (end of a universe).

So, in theory, there could have been a whole different universe before the big bang, but was compressed to one single point after it fell in on itself.

 

[Quds Akbar]

No, it did NOT and that in fact is the point of this thread. You should read threads before you reply.

According to Stephen Hawking'd book, A Brief History of Time, the Universe is expanding and the expansion is accelerating. So if time ran backwards then the Universe would have begun in an infinitely small and infinitely dense point, and it did. The Big Bang theory states that the Universe began in a singularity, you should read the book, it's a good one.

 

[phinds]

According to Stephen Hawking'd book, A Brief History of Time, the Universe is expanding and the expansion is accelerating. So if time ran backwards then the Universe would have begun in an infinitely small and infinitely dense point, and it did. The Big Bang theory states that the Universe began in a singularity, you should read the book, it's a good one.

I have read the book. Your analysis is not correct.

The universe started in a hot dense state. "Singularity" does not mean a point in space.

Also, if your analysis were correct, it would emphatically dictate that there is a center from which the expansion started and that in turn would imply a preferred frame of reference. We know empirically that neither one exists.

 

[PeterDonis]

I read a neat theory on how our universe is like a balloon; however it can save itself from popping by retracting back in.

Please give a reference.

 

[Monsterboy]

I read a neat theory on how our universe is like a balloon; however it can save itself from popping by retracting back in. The theory went on how the universe expands from a small scale (big bangs) and contracts from a large scale (end of a universe).

So, in theory, there could have been a whole different universe before the big bang, but was compressed to one single point after it fell in on itself.

The bouncing universe theory is disputed or even rejected.
http://www.nature.com/nature/journal/v302/n5908/abs/302505a0.html

 

[William Donald]

It was a Documentry uploaded on YouTube on space-time, now slices, and time dilation. I watched it many many months ago. I defiantly wouldn't remember how to find it. Sorry

 

[PeterDonis]

It was a Documentry uploaded on YouTube on space-time, now slices, and time dilation.

Even if you could find it, it probably wouldn't be a good reference. Please check out the PF guidelines for acceptable sources on this page:

https://www.physicsforums.com/threads/physics-forums-global-guidelines.414380/

Generally, a good reference is either a peer-reviewed scientific paper or a standard textbook. Lots of "documentaries" that appear on TV, even when they have reputable scientists in them, are not good references for discussion here, because they gloss over a lot of details and fine points that, while they may not be interesting to a general lay audience, are critical if you actually want to learn about the underlying physics, as opposed to just saying "wow, neat!" and moving on without delving any further.

 

[William Donald]

Even if you could find it, it probably wouldn't be a good reference. Please check out the PF guidelines for acceptable sources on this page:

https://www.physicsforums.com/threads/physics-forums-global-guidelines.414380/

Generally, a good reference is either a peer-reviewed scientific paper or a standard textbook. Lots of "documentaries" that appear on TV, even when they have reputable scientists in them, are not good references for discussion here, because they gloss over a lot of details and fine points that, while they may not be interesting to a general lay audience, are critical if you actually want to learn about the underlying physics, as opposed to just saying "wow, neat!" and moving on without delving any further.

Sorry for that. I thought since a theory is basically just an idea, it wouldn't matter. I didn't say it was a fact. I just mentioned it, because it relates to the original post. Feel free to delete it or something.

 

[Bandersnatch]

Sorry for that. I thought since a theory is basically just an idea, it wouldn't matter. I didn't say it was a fact. I just mentioned it, because it relates to the original post. Feel free to delete it or something.

Did you know, the word "theory" has got a diametrically different meaning in science than it has in everyday usage, which is the source of many a confusion (sometimes intentionally sown; e.g.: "evolution is just a theory!"

).
In common usage it means conjecture, speculation. A guess.
In the scientific context it's a hypothesis that passed rigorous testing. It is actually on the same level as "a fact".

On PF the latter meaning is assumed. Especially since speculative ideas are not allowed.

 

[dragoneyes001]

just a further question about the above. what he describes was a reviewed theory which was disputed or rejected. correct? so wouldn't that be actually discussing a "theory" and not simple speculation are we to never discuss subjects that have been rejected even unknowingly?

 

[Bandersnatch]

just a further question about the above. what he describes was a reviewed theory which was disputed or rejected. correct? so wouldn't that be actually discussing a "theory" and not simple speculation are we to never discuss subjects that have been rejected even unknowingly?

According to the guidelines:

Non-mainstream theories:
Generally, in the forums we do not allow the following:
Attempts to promote or resuscitate theories that have been discredited or superseded (e.g. Lorentz ether theory); this does not exclude discussion of those theories in a purely historical context

https://www.physicsforums.com/threads/physics-forums-global-guidelines.414380/

 

[dragoneyes001]

what i meant by unknowingly is not knowing the theory has been rejected/refuted.

 

[phinds]

what i meant by unknowingly is not knowing the theory has been rejected/refuted.

What are you arguing about? Nobody got in infractions on this, it was simply pointed out that the "theory" he mentioned does not fit the forum guidelines. If one doesn't know that a theory is inappropriate to discuss here because of the guidelines, does that then make it appropriate just because one didn't know?

 

[dragoneyes001]

why would you call asking for clarification arguing?

to answer your question: does it make them wrong or in breach of the guide lines if they didn't know the theory was refuted and did not promote it as fact but inquired if it was a valid theory?

 

[phinds]

why would you call asking for clarification arguing?

Fair enough. OK, to clarity: the fact that one does not know that a theory is inappropriate makes it (marginally) OK to have posted it but one should expect to be called on it by the mods (and possibly by other nitpickers like me) and possibly to have the post deleted.

 

[dragoneyes001]

i think you posted before i edited the above post please scroll up so there is no confusion.

 

[phinds]

why would you call asking for clarification arguing?

to answer your question: does it make them wrong or in breach of the guide lines if they didn't know the theory was refuted and did not promote it as fact but inquired if it was a valid theory?

It puts them in breach of the guidelines, exactly as one would be held liable for breaking a law. Ignorance of the law is no excuse. Now, if it's clearly an innocent breach, it's not likely to elicit anything more than having it pointed out that it is inappropriate, which is exactly what happened in this case.

We do occasionally have folks who insist on continuing to promote inappropriate theories but they don't generally last long unless they are willing to see the error of their ways.

 

[dragoneyes001]

thank you that's all i was asking.

 

[phinds]

thank you that's all i was asking.

Yeah, sorry if I got a bit snippy. Greg pays me to do that because by setting such a bad example, I make all the mods look good.:p

 

[dragoneyes001]

now to get back to the subject at hand is there a layman's way of explaining the universe was in a" hot dense state"

 

[phinds]

now to get back to the subject at hand is there a layman's way of explaining the universe was in a" hot dense state"

Hm ... that seems like a very straight-forward phrase to me, although it IS a bit of an understatement. "Hot" hardly begins to describe it. Are you familiar with the CMB? At the time, about 400,000 years after the singularity, there occurred the "Surface of Last Scattering", which we now see as the CMB, which is current about about 2.7degrees C. at the time of the SLS, it was 1000+ times that much, but this is downright cold compared to things earlier on.

I refer you to Steven Weinberg's "The First Three Minutes".

 

[dragoneyes001]

I was more aiming at the Dense part since it seems to be the most contentious part.

i have read about cosmic microwave background enough to understand its relation to the early part of development.

 

[Drakkith]

I was more aiming at the Dense part since it seems to be the most contentious part.

i have read about cosmic microwave background enough to understand its relation to the early part of development.

Well, since the universe is currently expanding, then that must mean that is was denser in the past than it is now. Extrapolating backwards using known physical laws, we find that the early universe consisted of a very dense, very hot plasma. The further backwards in time we extrapolate, the denser and hotter the universe becomes. The earliest, most dense, and hottest periods reach energy and density scales beyond our current knowledge, so we know very little about them.

We expect that at the temperature and density of this very early period, the matter in the universe consisted of a quark-gluon plasma, or even something more exotic.

 

[dragoneyes001]

I think this is where things get either misinterpreted or muddled. because as I'm understanding it the universe was smaller and then expanded but as has been said that would create a center from which everything is expanding away from which if I'm not mistaken is not the case right?

 

[Drakkith]

I think this is where things get either misinterpreted or muddled. because as I'm understanding it the universe was smaller and then expanded but as has been said that would create a center from which everything is expanding away from which if I'm not mistaken is not the case right?

The observable universe was smaller, not the whole universe. When talking about the universe as a whole, it usually better to think in terms of density rather than overall size or volume. An infinite universe can still contract or expand and it will remain infinite in size. The contraction/expansion happens everywhere, and all observers would see themselves as standing still while everything moves away from or towards them.