# Thread: Another dumb one

1. If most objects expand when heated then why does the universe not contract as it cools?

2.

3. Maybe the matter in the universe is contracting as it cools making the universe look bigger.

4. Originally Posted by zinjanthropos
If most objects expand when heated then why does the universe not contract as it cools?
Because materials expand, and so do gasses. The universe expands, the space time. But actually it does shrink. As galaxies remain at their size whereas the universe expands. By comparison, you could say that galaxies shrink with respect to the whole universe.

5. As usual I probably did not write the OP question correctly. How does heat figure into the BB theory? If space and matter both began at the BB then why would the heat transfer from the singularity to what amounts to nothing, assuming the singularity was all there was where did the heat go?

Did space emerge from the BB prior to matter? I just can't see how matter or heat could go anywhere without space.

6. You cannot assign any properties to the "singularity", so you cannot consider heat transfer from the singularity. A singularity is not physical, it shows that our theory of gravity has broken down and does not apply under the conditions.

All our scientific theories apply ONLY when the universe is not a singularity. So, for as long as a singularity falls out of the equations, we cannot make any predictions about anything to do with that singularity.

What we can do, however, is apply the laws of physics as soon as there is no singularity.

7. The whole concept of heat is related to the kinetic energy of matter.
Without space for matter to move in there is no kinetic energy.

I can never understand where the first kinetic energy came from.
The big bang happened equally at all points in the universe, so nothing can start by travelling away from the big bang.
When inflation stopped why was all matter not totally stationary in local space?

8. Because it was not all totally stationary before inflation.

9. Originally Posted by SpeedFreek
A singularity is not physical.
I'm confused. Is this a philosophical take? In order to comprehend the universe do I need to have faith in the non-physical? Does science believe in a rational explanation for the BB?

10. Originally Posted by zinjanthropos
Originally Posted by SpeedFreek
A singularity is not physical.
I'm confused. Is this a philosophical take? In order to comprehend the universe do I need to have faith in the non-physical? Does science believe in a rational explanation for the BB?
You just have to realise that Big-Bang theory does not describe the origin of the universe, it only describes its evolution, working backwards from what we observe today.

As things stand, science has no rational explanation for the Big-Bang, as science breaks down and shows singular behaviour at time=0, which is non-physical.

This does not mean that science says the universe came from a singularity, however many popular descriptions say so. It does not mean the universe came from something with no dimensions, or came from nothing. It simply means that we have no scientific knowledge of where the universe came from. The current thinking is that we need a theory of quantum gravity in order to look into the conditions where general relativity on its own predicts a singularity, as general relativity on its own is not enough.

Philosophically, I think science believes there is a rational explanation out there somewhere!

11. I have another dumb question:

If the Big Bang was not an explosion then why is there a shockwave? Is shockwave the wrong term? I've heard 'echo' used. Which term best exemplifies findings?

12. I've never heard either term used. I could assume what it is you're referring to (CBR) but I should ask first:
What are you referring to when you use that term?

13. Originally Posted by Neverfly
I've never heard either term used. I could assume what it is you're referring to (CBR) but I should ask first:
What are you referring to when you use that term?
Shockwave in the title, echo in the first paragraph of this article

14. Originally Posted by zinjanthropos
Shockwave in the title, echo in the first paragraph of this article
Ugh...

I chalk this one up to terrible journalism. Check out these gems:
As yet, scientists cannot see beyond the cosmic microwave background, which blocks the first 380,000 years of the universe from view.
Scientists generally agree that the primeval detonation of matter, which they say took place some 13.7 billion years ago, led to the creation of the universe.
To the bit in bold: <facepalm>
Another facepalm here:
echoes of the primeval explosion,
This was a Journalist who was not knowledgeable about the subject matter. It's not unusual- I'm still laughing over the article that referred to parafinic compounds found in space as "Waxy Hydrocarbons."

15. Here is a more proper explanation, firstly in web-form, and then as a pdf file.

Big Bang Acoustics

http://www.astro.virginia.edu/~dmw8f/sounds/aas/echoes.pdf

And the wiki:
Baryon acoustic oscillations - Wikipedia, the free encyclopedia

16. From the first article:
Finally, there was a sub-stratum of an unusual dark fluid – called "dark matter" – most likely made from an unknown kind of heavy particle. This dark matter was six times denser than atomic matter, and was the dominant source of gravity after 60,000 years. This sets the stage for all subsequent structure formation and is a primary, though silent, player.
I guess I don't quite understand how the universe was composed of light gases before stars came along and then find out a heavy particle may have existed early on. Perhaps I'm confusing atomic matter with some other type, what is/are the other type(s)? By light do they mean less dense?

17. The heavy particle is thought to only interact weakly with other matter.

Weakly interacting massive particles - Wikipedia, the free encyclopedia

Unless I am misunderstanding you, on the page you quoted, light means light - electromagnetic radiation.

18. Concerning dark matter, are we looking at BB residue, matter that was not affected by the BB?

19. Originally Posted by zinjanthropos
Concerning dark matter, are we looking at BB residue, matter that was not affected by the BB?
The majority of Dark Matter is hypothesized to be non-baryonic matter. Unlike ordinary matter, non-baryonic dark matter contains no atoms and would only weakly interact with matter or EM.
Cold dark matter - Wikipedia, the free encyclopedia
Getting warmer...:
Warm dark matter - Wikipedia, the free encyclopedia
Hot, hot hot:
Hot dark matter - Wikipedia, the free encyclopedia

20. Originally Posted by zinjanthropos
Concerning dark matter, are we looking at BB residue, matter that was not affected by the BB?
What do you mean "not affected by the BB"?

Dark matter is thought to be affected by the expansion of the universe, just like everything else. In relation to the BB, dark matter has the same status as normal matter.

21. When I ask these questions I'm always concerned whether or not there is a true definitive answer to them. IOW should I continue to ask questions regarding the universe here if I think there is no real answer. Now if one of my questions falls into that category and the only answers are either personal theories or accepted hypotheses then should it be moved to another subforum, i.e. Trash, Philosophy, Pseudo? I believe my next question may belong to the unanswerable but I will ask it anyway: Why is there a speed limit for light or why can't light go faster?

22. Originally Posted by zinjanthropos
Why is there a speed limit for light or why can't light go faster?
Well, there seem to be two possibilities: either the speed of light is finite or it is infinite. I have seen an argument that the universe as we know it could not exist if the speed of light was infinite - although I don't really remember what it was; probably related to the fact that there would be non concept of cause and effect, before and after.

So if we assume light speed has to be finite, then why does it have the value that it does? It appears to be because the permittivity and permeability of empty space have the values they do.

But why do they have these values?

At this point you need to watch Feynman's video on "why questions". You can always keep asking, "yes, but why?"At some point you always have to say, "because that's just the way it is".

In fact, that is a good answer to the question, "Why is there a speed limit for light?" Because there is.

23. Originally Posted by zinjanthropos
If most objects expand when heated then why does the universe not contract as it cools?
By the way, there is no such thing as dumb questions. Just poorly questioned and dumbly answered. If you make a well focused question, it is never dumb. Its answer might be simple, but it is never dumb.

24. Timothy Ferris says that questions are more important than answers.

25. Couple more: I going to assume for this question that the presence of matter stretches spacetime. I'm not even sure if that's how to word it exactly. In any case if such a thing occurs then is there a formula or equation that signifies just how much we can expect a certain quantity of matter to affect spacetime? Am I confusing the stretching with gravity?

26. Originally Posted by zinjanthropos
Couple more: I going to assume for this question that the presence of matter stretches spacetime. I'm not even sure if that's how to word it exactly. In any case if such a thing occurs then is there a formula or equation that signifies just how much we can expect a certain quantity of matter to affect spacetime? Am I confusing the stretching with gravity?
Yes to all. Yes, you're right to not be sure if that's how to word it.
Yes, there is a formula/equation to describe it. Go to Green. (Unless you want to talk about Minkowski space, DeSitter space, coupling scalar fields, metrics... I mean... I won't stop ya )
Yes, the warping of spacetime or "stretching" as you called it is the effect we see as gravity.

27. Originally Posted by Neverfly
Originally Posted by zinjanthropos
Couple more: I going to assume for this question that the presence of matter stretches spacetime. I'm not even sure if that's how to word it exactly. In any case if such a thing occurs then is there a formula or equation that signifies just how much we can expect a certain quantity of matter to affect spacetime? Am I confusing the stretching with gravity?
Yes to all. Yes, you're right to not be sure if that's how to word it.
Yes, there is a formula/equation to describe it. Go to Green. (Unless you want to talk about Minkowski space, DeSitter space, coupling scalar fields, metrics... I mean... I won't stop ya )
Yes, the warping of spacetime or "stretching" as you called it is the effect we see as gravity.
Holy Christ.....maybe I shouldn't have asked. From the article:
Despite the simple appearance of the equations they are, in fact, quite complicated.
They don't look simple to me. Makes me appreciate the great man(Einstein) a lot more, especially if those in the know find it complicated. I best stay away from this type of question in the future.....although I did get the answers.

28. (chuckle)
Well, in defense of the article, it's not unusual (I'm sure it's often been observed firsthand on here) that some guys will grab the basic equations and try to do things with them you shouldn't be doing. Aside from dope, I mean- misapplying the math.
The equations look simple because in some ways, they are simple. The application, however, can be complicated and the warning someone snuck in there may serve to show that you cannot just grab some equation, think that's all there is to it and start plugging in numbers and playing with it, thinking you've found the answer to the Universe and going on science forums debunking Relativity.
To those in the know, it's not quite so complicated (Tedious could be a better word.)

29. Originally Posted by zinjanthropos
Couple more: I going to assume for this question that the presence of matter stretches spacetime. I'm not even sure if that's how to word it exactly. In any case if such a thing occurs then is there a formula or equation that signifies just how much we can expect a certain quantity of matter to affect spacetime? Am I confusing the stretching with gravity?
Has anybody considered
quantum foam can be used as a qualitative description of subatomic spacetime turbulence at extremely small distances (on the order of the Planck length). At such small scales of time and space, the Heisenberg uncertainty principle allows energy to briefly decay into particles and antiparticles and then annihilate without violating physical conservation laws. As the scale of time and space being discussed shrinks, the energy of the virtual particles increases. According to Einstein's theory of general relativity, energy curves spacetime. This suggests that—at sufficiently small scales—the energy of these fluctuations would be large enough to cause significant departures from the smooth spacetime seen at larger scales, giving spacetime a "foamy" character.

Quantum foam - Wikipedia, the free encyclopedia
If true it might explain why light has a speed limit as the quantum foam has properties that cause that speed limit. Secondly, maybe the quantum foam can be used to explain the expansion of space in that it creates a very small pressure that adds up over millions and billions of light year distances.

30. Originally Posted by arKane
Originally Posted by zinjanthropos
Couple more: I going to assume for this question that the presence of matter stretches spacetime. I'm not even sure if that's how to word it exactly. In any case if such a thing occurs then is there a formula or equation that signifies just how much we can expect a certain quantity of matter to affect spacetime? Am I confusing the stretching with gravity?
Has anybody considered
quantum foam can be used as a qualitative description of subatomic spacetime turbulence at extremely small distances (on the order of the Planck length). At such small scales of time and space, the Heisenberg uncertainty principle allows energy to briefly decay into particles and antiparticles and then annihilate without violating physical conservation laws. As the scale of time and space being discussed shrinks, the energy of the virtual particles increases. According to Einstein's theory of general relativity, energy curves spacetime. This suggests that—at sufficiently small scales—the energy of these fluctuations would be large enough to cause significant departures from the smooth spacetime seen at larger scales, giving spacetime a "foamy" character.

Quantum foam - Wikipedia, the free encyclopedia
If true it might explain why light has a speed limit as the quantum foam has properties that cause that speed limit. Secondly, maybe the quantum foam can be used to explain the expansion of space in that it creates a very small pressure that adds up over millions and billions of light year distances.
Universal Twinkie.
Whenever Quantum Foam takes a topic, it makes me want snacky cakes. I find Quantum Foam intriguing. And delicious.

31. So, I just checked out the Quantum Foam idea really quickly. And It looks like we will have look into the vacuum energies of QFT. That will take a while :P

32. Guys...this stretching of spacetime terminology has me confused. I mean in order to stretch something then wouldn't the affected area need to be anchored somehow between at least two points? What's holding spacetime in a position so that it can be stretched? Would distort be a better word?

33. Stretch, distort, flow, curve - these words are ALL analogies used to describe the results of the mathematics (the Einstein Field equations) which give us the equations for geodesic motion. These equations describe the changes in the relationship between things across space and time. They describe how objects fall in a gravitational field. They describe how objects orbit. They describe how objects interact, due to gravitation.

Matter tells space-time how to curve, and the curvature of space-time tells matter how to move. The curvature of space-time is what we call gravity.

34. I've seen that comic strip before and I get it. I only hope that I can phrase a question correctly before I type. For this I fail miserably but it won't stop me. Perhaps there should be another category in the forum that is akin to New Hypotheses & Ideas or even Pseudo Science. I would call it the Layman's Perspective. I can pick up any book on a science discipline such as Cosmology for instance and while reading it, form concepts and images in my mind or find something I think contradictory to something else I read previously. It's not new ideas, just viewpoints. What do you think?

35. Originally Posted by zinjanthropos
I've seen that comic strip before and I get it. I only hope that I can phrase a question correctly before I type. For this I fail miserably but it won't stop me. Perhaps there should be another category in the forum that is akin to New Hypotheses & Ideas or even Pseudo Science. I would call it the Layman's Perspective. I can pick up any book on a science discipline such as Cosmology for instance and while reading it, form concepts and images in my mind or find something I think contradictory to something else I read previously. It's not new ideas, just viewpoints. What do you think?
There is room for the layman's perspective in any of the forums, so do not feel afraid to post, zinjanthropos. I was not trying to belittle or ridicule your question, and your question was not incorrectly phrased either. Please feel free to carry on.

In my last post I was going to try to describe the anchoring you were referring to in relation to stretching spacetime by using curvature instead as I couldn't find a way to physically describe it, but realised that I ran into the same problem using curvature. That made me remember the cartoon, so I posted it instead.

All I was doing with that cartoon was posting a humorous but none the less true statement about the situation - when it comes to General Relativity, all analogies are just analogies.

We can work with analogies, in order to aid understanding of science, but we cannot do any actual science with them.

But seeing as this is all about the understanding, I say carry on wherever you like!

36. This one may be tough to phrase but here goes: As objects move about in the universe, does spacetime pass through them or move out of the way?

37. Originally Posted by zinjanthropos
This one may be tough to phrase but here goes: As objects move about in the universe, does spacetime pass through them or move out of the way?
That is a really good question.

I'd offer my own speculations on it... Spacetime is all the spaces between. Even a planet is filled with empty space, between the particles, even.

38. Originally Posted by zinjanthropos
This one may be tough to phrase but here goes: As objects move about in the universe, does spacetime pass through them or move out of the way?
Hmmm... The question suggests that spacetime is made of "stuff". It may be better to just think of it as the set of coordinates, the geometry, that describes the relationship between things in time and space. A mathematical abstraction, if you like.

39. More importantly, spacetime is the set of all point events. Your worldline is static in this framework, you are no more moving through spacetime than a picture is moving through the canvas it is painted on.

40. Originally Posted by river_rat
More importantly, spacetime is the set of all point events. Your worldline is static in this framework, you are no more moving through spacetime than a picture is moving through the canvas it is painted on.
Does this make time a real thing and not some abstract thought or concept? If my worldline doesn't move then does that mean it would be impossible for me to move through time, as into the past or future?

41. Originally Posted by river_rat
More importantly, spacetime is the set of all point events. Your worldline is static in this framework, you are no more moving through spacetime than a picture is moving through the canvas it is painted on.
Predestination?

42. Dark energy causes the universe to expand from all points faster than the speed of light. Dark matter tries to prevent this and fails epically.

43. Originally Posted by zinjanthropos
Does this make time a real thing and not some abstract thought or concept?
I don't understand the question. Your world line is your entire history, past present and future. Remember GR is a deterministic theory - once the boundary conditions are set the whole thing is fully specified.

44. Originally Posted by river_rat
Originally Posted by AlexG
Does this make time a real thing and not some abstract thought or concept?
I don't understand the question. Your world line is your entire history, past present and future. Remember GR is a deterministic theory - once the boundary conditions are set the whole thing is fully specified.
Wrong name on that quote. It's not mine.

GR may be deterministic, but Quantum Theory isn't, and they both have their realms of applicability. Any merger of GR and QT must, of neccessity be non-deterministic.

45. Originally Posted by river_rat
Originally Posted by AlexG
Does this make time a real thing and not some abstract thought or concept?
I don't understand the question.
That makes two of us. I forget what I was thinking when I wrote the question. I think it was something to do about time being a coordinate.

46. Originally Posted by AlexG
Wrong name on that quote. It's not mine.
Sorry - corrected

GR may be deterministic, but Quantum Theory isn't, and they both have their realms of applicability. Any merger of GR and QT must, of neccessity be non-deterministic.
Or be superdeterministic - we dont really know.

47. Originally Posted by river_rat
Or be superdeterministic - we dont really know.
What is 'superdeterministic'? It's either deterministic, or it's not. Yes or no, 1 or 0, a simply binary question.

If you introduce uncertainly into a certainty, it's no longer a certainty.

48. Originally Posted by AlexG
What is 'superdeterministic'?
Uncertainty can come from multiple sources, the two obvious ones are incompleteness of the model and the other is that the phenomena in question is truly random.

For example, a coin flip is not "truly random" in that given perfect knowledge of the initial conditions of the system you should be able to predict which side the coin will land. We do not have perfect knowledge and so we average out all these effects as randomness in the system. The true variables are hidden from us.

Now the question is if the randomness in Quantum Mechanics is due to us not having full knowledge of the underlying mechanics and averaging out this uncertainty through randomness or that the universe at the quantum level truly is random. This opens up the whole idea of local hidden variable theories and the Bell inequalities etc.

Superdeterminism is a way of getting around the implications of the Bell inequalities regarding local hidden variable theories and supposes that every action in the universe is deterministic ie. there is no free will.

49. But just to remind you, super determinism is (just like the others) an interpretation. It turns out to not yet be reconcilable with experimental results.

50. Originally Posted by zinjanthropos
Did space emerge from the BB prior to matter? I just can't see how matter or heat could go anywhere without space.
The BB did not expand into something, it expanded from something. In fact, during the inflation epoch, universal constants such SOL did not apply because spacetime did not exist outside of the expanding spacetime geometry.

51. As I see it, the Layman's Perspective: I'm trying to formulate a picture in my mind. I don't like the rubber sheet analogy for gravity anymore so I'm now imagining that every object with mass is surrounded by concentric spheres of influence. The denser the object the denser the spheres of influence surrounding that object. How am I doing so far?

52. Sometimes, I'm surrounded by dense oblate spheroids of influence.

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