Image: NASA
Questions answered in this episode:
"If the multiverse theory is true and other universes truly exist, and let's say we had the technology to escape our universe and go into interuniversal space...since time only exists because of the big bang and there are other "times" in different universes same as our own then what about the area in between the universes does time exist there?" - Barrows0re
"With the theory, or fact, that the universe is expanding how does science determine the edge of the universe? And once the energy/forces which drives the expansion is spent and the universe begins to shrink what is left in it's place? The same void/nothingness before expansion? Thank you." - patrick pegasus
Submit your questions for the next round of Ask the Experts by clicking here and posting in the YouTube comments (Google account required). And while you're there be sure to subscribe to the Spacelab channel for weekly videos on space and astronomy.
The question with the most "likes" will be answered in the next video by a new guest expert. Previous episodes have featured astronomer Caleb Scharf, astrophysicist Neil deGrasse Tyson and Scientific American's own editor in chief, Mariette DiChristina.
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27 Comments
Add CommentSo how did the multiverse begin, and what happened before that? How do we know that there is a standard multiverse time? Is there a spacetime that encompasses all multiverses, or are their multiple instances of multiverses? This is soooo interesting <%)
Reply | Report Abuse | Link to thisClearly theoretical physicists, and particularly particle physicists, are lost in the cosmos without a reliable paradigm to guide them. Alas, they have also thrown their empirical compass overboard because it kept indicating that they had deviated from the proper course to a unified understanding of nature.
Reply | Report Abuse | Link to thisThus, we have unobservable strings and branes, unobservable WIMPS, an unobservable multiverse, unobservable extra-dimensions, and a host of other unobservable hypothetical particles and phenomena, not to mention a Planck mass that is off by 19 orders of magnitude, postmodern anthropic philosophizing and excessive reductionism.
Want to see a theory of principle, i.e., a reliable paradigm that can make definitive predictions about specific phenomena ranging from subatomic scales to galactic scales, and that has already passed several unique observational tests?
Have a look at: http://www.academia.edu/2631862/Predictions_of_Discrete_Scale_Relativity .
Robert L. Oldershaw
http://www3.amherst.edu/~rloldershaw
Discrete Scale Relativity/Fractal Cosmology
I love science. I defend the fact that government money is allocated to it, I accept the fact that science of today is technology of tomorrow. I do however, wonder what possible result could come from all of the effort put into theories of universes that may or may not exist, with zero evidence to support such a study, and not even a theory on how one might find evidence of this theory?
Reply | Report Abuse | Link to thisIf Mass is congealed energy (e=mcc) then what is energy?
Reply | Report Abuse | Link to thisPresumably mass is a cold state representation of energy that can be modified by other energy to produce more or less mass.
Conservation of energy appears to be a given.
Is Energy then just space...if so, is there a conservation of space?
Big bangs and Multiverse do not seem to resolve the nothingness equilibrium of everything.
Thank you
Physics needs to provide more plausible answers to this sci-fi multiverse abstraction. If they exist, where are the boundaries? Our universe is homogeneous, non-central and expanding, so where do you look for some kind of transition? How would we know when we saw it? Would it be an infinite zone of annihilating, dissimilar particles? If not, then the boundary would be a smooth transition telling us nothing about any differences and would just be an extension of our universe. Since this concept appears to be non-falsifyable, it smacks of voodoo meta-science.
Reply | Report Abuse | Link to thisScientists have to make their livelihood through answering some complicated scientific questions. Typically, they need to provide a convincing data that is reproducible. However, seems like in the field of research of the Universe, they need to come up with a complicated explanation, of something thing that really may not be there, and they do not need to provide any reproducible and verifiable data. As long as they make the theory so complicated that refuting that theory becomes supper complicated, they get fifteen minutes of fame. Truth is, it is beyond comprehension of human mind. What was before big bang? if there was a big bang. If there are Multiverses, how did they come to being? Strongly believe in the quote "Believing in either theory of creation or evolution strongly indicates one's limited capability of thinking."
Reply | Report Abuse | Link to thisVery well expressed. These explanations should be easily understood by most educated people, even if theoretical physics is not their particular field. Thank you Mr. Olson.
Reply | Report Abuse | Link to thisNothing is beyond the comprehension of the human mind. For if we cannot comprehend it fully we can create a system that can, and thus we will.
Reply | Report Abuse | Link to thisFor one thing I would like answered do all black-holes spin in the same direction, meaning the universe is spinning, and possibly we are apart of a 5th dimension which is both larger than us and compacted which created us.
Sure its difficult for us to measure things we do not know anything about, but that is now and in the future youll find we will. Long after your limited brain has gone to dust.
Absence of evidence is not evidence of absence.
Reply | Report Abuse | Link to thisHonestly this is the oldest line in theoretical physics. Just because we don't know doesn't mean the answer isn't exactly what we think it will be, it can also be something different, it matters not.
A Question: Heard this from a friend,
Reply | Report Abuse | Link to thisquestion is about the speed of light...sorta....
Which is faster? speed of light or speed of magnetism/gravity.
If it were possible for the Sun to instantly be removed from our solar system, would there be an 8 min. delay before the planets spin off into space or would the lack of gravity/magnetism be instant in it's non-effect.
strange question, but thanks for an answer.
bob ventura, ca.
Its all turtles!
Reply | Report Abuse | Link to thisSingularity means there is one and only "Source" that contains everything that happened and will happen.
Reply | Report Abuse | Link to thisMatthew Kleban:
Reply | Report Abuse | Link to thisThank you for the excellent answers. Here are some related questions that you requested:
1. In your reference to "Flatland", the 3_D sphere passing thru the plane starts as a point, expanding to concentric circles. In our 3-D universe, would collisions with other universes appear as expanding spheres, proceeding from a point out of 'nothing'. Would a such collisions show any evidence in the CMB data?
2. Would a 'passing' (non-colliding) universe show any gravitational effects? I am thinking of Caleb Scharf's description of 'Dark Flow' in his recent book.
3. Is there any evidence that our universe is rotating? Does Dark Flow indicate a rotation?
Thanks again for your instructive answers. This is what Scientific American used to be like, many years ago.
At bolo g gorkman
Reply | Report Abuse | Link to thisEinstein did special relativity to answer the question of what is the fastest speed, hence he found gravity travels at light speed or at least almost as fast.
Then after he did special relativity, he used that to make general relativity proving Newton inaccurate in many ways, for instance.
When an object is accelerated it requires more force as it gets faster, meaning an object just short of light-speed would need an infinite amount of energy to get it to light-speed. Thus F=ma was proved to be wrong and should only be used for stationary or really slow moving physics or for artistic purposes only.
Another more exciting phenomenon, is string theory, with its one dimensional string. Seeing as the only way to achieve a one dimensional object is a stationary wave, the universe would have to be cold and blackholes cannot make a singularity as they are hot.
Reply | Report Abuse | Link to thisTherefore why do people refer to blackholes as singularities when its impossible, as the most they can only be a 2D brane, meaning string theory in itself declares itself an invalid theory. Funny hey.
Therefore the mulitverse is a relevant hypothesis, but too many different people have different ideas what a mulitverse is. Perhaps some new terminology for it needs to be created.
At bolo g gorkman part 2
Reply | Report Abuse | Link to thisSo if you like, if the sun suddenly was "stolen", you would still see it for as long as the light is still travelling, then it would go black for you, then a moment later the planet would leave its orbit.
You would then start getting a little cold, and have to turn the heaters on to survive. We would have to generate enough heat for us to survive, but I dont think the planet would get much lower than -60 deg.
To,
Reply | Report Abuse | Link to thism,
You are getting emotional in a scientific discussion, do you really understand what is being discussed? I hope your illuminated brain can tell us what will be found, as you stated in reply to me "Long after your limited brain has gone to dust." Just fancy and fascinating theories without reproducible scientific evidence can go only so long, Hollywood produces better stories.
I have decided that it's time to come up with yet another 'theory as to how this universe came to be. As long as we keep a distance between our theories and any possibility that they could be a ( watch for it ) Supreme Being
Reply | Report Abuse | Link to thisSpinoza posits that the universe is infinite and is its own cause from which proposition he creates an ethical system based on a worshipful acceptance of that infinite universe which system, if followed, will make one happier than one would otherwise be (if not absolutely happy). Has Professor Kleban formed an opinion about that proposition?
Reply | Report Abuse | Link to thisThis is for the other commenters. They object to these theories because they violate some ideas that seem obvious and inescapable. But there is a mistake: human intuition was developed over millenia, and it dealt with events and objects roughly at the human scale. Our historical intuition never encountered femtoseconds or gigayears or proton diameters or the diameter of the universe. This means that one mustbe extremely careful and skeptical when disavowing something because it violates intuition. Consider time depending on gravity, or velocities adding nonlinearly, or entanglement, uncertainty, duality, superposition, and all the other gross violations that have been proved to be correct.
Reply | Report Abuse | Link to thisYes. Gravity is known to propogate at the speed of light. IF the sun magically disappeared it would indeed take 8 minutes for the earth's motion to become a straight line.
Reply | Report Abuse | Link to thisMrBip said: "Gravity is known to propogate at the speed of light." Actually, only theory predicts that gravity propagates at the speed of light. Since Gravitational Waves have not been detected yet, there may not be any real evidence of this equality, but many theorists assume that it is the case.
Reply | Report Abuse | Link to thisRead balloon inside balloon theory of matter and antimatter universe on opposite entropy path and producing dark energy at common boundary by annihilation and injected into our universe as graviton and anti graviton , now found as two HIGGS BOSONS in LHC at CERN.
Reply | Report Abuse | Link to thishi,my question is that . will it be possible to build a bridge of inter connected satillites to control a primary satllite to explore deeper parts of space.
Reply | Report Abuse | Link to thisbolo g gorkman, I got these answers from friends Rick and Rob:
Reply | Report Abuse | Link to thisThe answer is it would take eight minutes until the earth felt the sun's disappearance. Gravity waves also propagate at the speed of light. This was in Scientific American about four years ago. It's been proven true.
As said above. Otherwise you could communicate FTL with gravity waves (given a massive leap in technological capability, obviously) which ain't allowed! Same applies if you had a solid object between here and Proxima Centauri (for example) and shifted one end at near the speed of light. The movement would travel along the object at C (despite being 'solid'), making the other end move after a delay of 4.2 years!
Great question. Since gravity is a result of spacetime curvature, the curvature would I assume happen instantly, or at the speed of light, so my guess is the faster or the same, but not slower.
Reply | Report Abuse | Link to thisnot to put too fine a point on it,
Reply | Report Abuse | Link to thisor to be too much of a nag,
however,
time has no beginning. -
I love this expansion word.
how about already.
guess what's not perfect.