Was the Big Bang a WHITE hole?

a white hole is the exact opposite of a black hole at least in terms of time anyway that means is that if you were able to look at the regions around a black hole and you were able to fast forward through time watch everything run and see the universe play out you would see that all the mata that was close enough to that black hole would eventually spiral in fall in and become a part of that black hole's mass another way of putting that is that for that matter the black hole is always in its future right there's no other scenario that exists gravity will always win a white hole though is the opposite for a white hole if you were able to fast forward through time and watch the universe run around a white hole what you'd see is mata spilling out of it like repelled by the white hole and so the way you can think about that is that for that matter that's being spilled out the white hole is always in its past and when i tell people this people like well that sounds pretty similar to like the big bang and like mata's spewing forth so people can't help but wonder was the big bang a white hole so if you're a space enthusiast you might have come across the term singularity before and this is essentially the mathematical description of what a black hole is the way that we form a black hole is when a massive star runs out of fuel and dies so if you think about a massive star that's a lot of matter there that's a lot of gravity that's trying to crush that star inwards there's a lot of things that can resist that crush of gravity inwards when a star is happily burning hydrogen into helium nuclear fusion like the sun is currently doing then there's energy from those reactions pushing outwards and resisting that crush of gravity when a star runs out of fuel the star starts to collapse and depending on how massive the star is various different things can resist that collapse instead of the energy produced by nuclear fusion so something like the sun for example would become a white dwarf and that'll be the pressure from electrons that resists gravity crushing it down a star more massive will become a neutron star and then it's the pressure from neutrons just being as closely packed as they can be that's resisting that crush of gravity down when you reach the limit though for what neutrons can't resist anymore then gravity wins right and the whole star starts to collapse down and then gravity becomes strong enough the light can't escape and so you get this event horizon where you no longer get any light from it's this 3d sphere around what once was a star where there's no longer any light or information what's inside of that because we can't get any lighter information from it is anybody's guess and i've done a video on this channel before on what we might think is inside a black hole long story short the mathematical description of it is a singularity if you run through all the equations of einstein's theory of general relativity which is our best theory for how gravity works and essentially what you end up with is all the matter that was in the star crushed down into an infinitely dense infinitely small point in space that we call a singularity but black holes are not the only thing that us physicists describe as singularities we also describe the very early universe in this way as well now i've done a lot of videos on this channel before about our best model for how the universe has evolved the big bang especially in my great debate series which looked at like the history of people collecting all the evidence and deciding what was the best model to describe this evolution and that the big bang eventually came out on top essentially one of the biggest pieces one of the earliest pieces of evidence that we had was essentially when we look out into the universe the majority of galaxies except for our nearest neighbors anyway like the andromeda galaxy for example which will actually collide with the milky way in a couple of billion years at time every other galaxy is actually moving away from us and this was first spotted in the 1920s by edwin hubble when he noticed that the light from all the galaxies has a doppler shift the light has been red-shifted it's been stretched out on its way to us and that has been interpreted for a long time as the universe space itself expanding again if we think about rewinding time and we think about the fact that if the universe is expanding and we re-round time the galaxies would get closer together until you got right to the very beginning where everything all the matter and energy in the universe was compressed into an infinitely dense and infinitesimally small point that we call a singularity so that often leaves people to wonder well how did the expansion of the universe start in the first place because everything being in this infinitely dense point of a singularity sounds a lot like a black hole like how come the universe wasn't just trapped inside a black hole well in alexander's theory of general activity mass curves space-time and that's what gives us the effect of gravity so you can picture that at least in two dimensions anyway by putting like a basketball in the middle of a trampoline then you take like a ping pong ball and roll in a straight line and it will follow the curved path of the trampoline like the trampoline is space in this analogy so mass curves space and that's what causes the effect of gravity that causes planets to orbit things but it's just kind of space it curves space time this like four dimensional thing that einstein brought together in his theory of relativity and what it means is that big masses also affect time too it means time slows down around a black hole which was a whole plot point in the film interstellar as well which annoyed me to know and and also forms the whole basis for a stargate sg-1 episode as well which i reacted to recently but anyway we're not a massive dungeon here my point is it's not just mass that can curve space-time it can affect space-time in this way the expansion of space also affects the curvature of space-time and in the very early very dense universe it was the effects of the expansion that dominated over the gravitational effects and therefore we didn't end up trapped in a black hole so what is the difference between these two singularities then the singularity in the very early universe and the singularity of a black hole well if we think about that idea of playing time forward again around these two singularities the singularity in the very early universe looks like the time reversed version of the black hole singularity looks like a white hole the exact opposite of a black hole like in a black hole how things can't get out in a white hole things can't get in and like how a black hole once it's formed is gonna live forever and exist forever afterwards a white hole must have existed forever before that since the beginning of time itself like the big bang suggests so this leads people to the question was the big bang a white hole and you can see why these singularities have been intrinsically linked for so long for so many decades here's a list for example of all the types of the different singularities from a paper by roger penrose from 1974 he's a famous mathematician stephen hawking's colleague and a recent nobel prize winner as well what you can see is that big bang and the white halls are listed as two different singularities now before we go any further i think it's worth pointing out two things here the first one is that white holes are completely hypothetical and theoretical objects unlike black holes which we have actually found and observed in the universe for a long time sure people thought that quasars might have been white holes but it turned out that actually they were just supermassive black holes that were accreting so much matter that the matter started to glow and could be seen at huge distances in the universe the second thing i want to point out is that even though they're completely hypothetical and theoretical we have no idea of how a white hole would even form a black hole forms when a star goes supernova and collapses down if we were to play that in reverse you would have an event horizon spewing out a functional star right that's like the astrophysical equivalent of like a sheet of glass unbreaking itself or even like an egg unscrambling self right it's so unphysical in fact it breaks one of the most fundamental laws of physics that entropy must always increase the universe must always get more disordered on top of that if you stimulate a white hole not even forming just existing right or even just run the maths of it run into problems all over the place it's incredibly unstable and what happens is that the white hole ends up just collapsing down and becoming a black hole so even if maybe they did exist in the early universe like they would probably die very quickly and become a black hole anyway so yes a white hole is mathematically feasible but physically speaking not so much now that's not a reason to rule it out as something that could explain the beginning of the universe and this the start of the expansion but something else is leave it this way whitehalls are singularities in space but the big bang is an expansion of space itself right it happened everywhere all at once pick a point in space here here or here the big bang happened in all of those places another way of putting that is that the big bang is a singularity of all space-time everything we were all once part of this singularity also the big bang didn't produce mata out of the singularity repelling it away from it like in a white hole all the matter was already there in the form of energy and that's just sort of been adapting to the ever-changing density of the universe ever since the expansion started and this is where a lot of confusion comes in about the big bang because people think that the big bang is a moment of creation it's not get rid of that idea from your head once and for all just it's not a moment of creation the big bang is a theory on the evolution of the universe it's history from the earliest moments to now and that model and our physics takes us all the way back to 10 to the minus 36 seconds that's a naught point and then 35 more notes and then a one seconds earlier than that um we don't have any model or theory that can explain what's going on at all because the temperatures and energies densities and forces are all so high that at that point gravity becomes as strong as the strong force the force that binds together atoms and protons and neutrons so to describe that weird and wonderful world you need a theory of quantum gravity in fact you need a grand unified theory affectionately known as gut that combines the four forces gravity electromagnetism the strong and the weak force with quantum physics that doesn't exist no one's figured it out yet and it's why we don't have any idea of what happens to this singularity at t equals zero because before 10 to the minus 36 seconds we have no way of describing it because general relativity which is usually what we'd use to describe singularities completely breaks down so we can't ever really compare the big bang singularity and white horse singularities hence why penrose listed them separately in his paper all the way back from 1974. now there are models or theories that try and explain you know what ignited or seeded the expansion of the universe like in the first place but the problem with these is you can't prove one over the other because whatever process they come up with it has to leave some form of imprint on the universe that we can observe today in order to be able to say it's that one over the other one you know something in like galaxy positions or the cosmic microwave background you know some ripple that's left over from whatever started the expansion that we can then test for without that though and without some grand unified theory of quantum gravity you know all of this just becomes complete and utter speculation and speculation can lead you down some very weird and wonderful rabbit holes of thought and questioning so instead of asking things like you know is the big bang a white hole you actually find people asking now and work in this sort of very theoretical area of physics asking questions like do all black holes contain other universes entirely before we get to the bloopers i want to say a huge thank you to this week's video sponsor brilliant the problem with big questions like is the big bang a white hole it's just the sheer amount of background knowledge you need to be able to even understand how to answer that question you know on like cosmology general relativity even basic math stuff like calculus as well but if you want to dive into this stuff where do you even start well brilliant is a website and an app that allows you to do just that with courses on a huge range of science and math topics that are interactive and get you to learn by doing i think that's the best way to learn honestly and if you've been here a while now you'll have heard me wax lyrical about brilliant before but what impresses me most about them is the effort that they've put into actually upping that level of interactivity on their courses even more so why not dive into their astrophysics course today especially their cosmology section to learn more about the cosmic microwave background or how the universe might end for all this and more head to brilliant.org forward dr becky that's d-r-b-e-c-k-y the link is in the video description down below head there to try out for free and get 20 off an annual premium subscription so thank you so much to brilliant for sponsoring this video and now we can roll those bloopers if you've run through all the equations of einstein's theory of general relativity which is the best theory we have to describe how gravity works there's like a weird crease in the curtains that kind of looks like a velociraptor again we have to dive into einstein's theory of general relativity here here i'm still there freaking definitely the second thing i want to point out is that what do i i don't actually know what i want to point out we don't know how white holes fall [Music] when you're spewing out matter cause you're a white hole right oh yeah

Channel: Dr. Becky

Views: 421,604

Keywords: science, dr becky, becky smethurst, rebecca smethurst, women in stem, women in science, stem, steminist, female physicist, astrophysics, physics, astronomy, universe, cosmos, galaxy, milky way, philosophy, hubble, big bang, in the beginning, expanding universe, energy, creation, cosmology, einstein, general relativity, black hole, white hole, wormhole, expansion of the universe, singularity, schwarzschild, roger penrose, theory, hypothesis

Id: VR0xCO7BFgo

Length: 15min 26sec (926 seconds)

Published: Thu Sep 23 2021