The Royal Institution
The Royal InstitutionWhat happened at the beginning of the universe, before the hot big bang? Join astronomer David Mulryne as he gives an introduction to cosmic inflation.
Watch the Q&A here: https://youtu.be/Wm24V0Q2p5E
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This lecture was recorded at the Ri on 13 July 2023.
For years, there has been a broad consensus in the cosmology community that the ‘hot big bang’ accurately describes the history of our universe since it was less than a few seconds old. But the question remains, what came before the hot big bang?
David Mulryne delves into the limitations of our current thinking and sheds light on the questions that remain unanswered. According to the hot big bang model, the Universe grew from a hot dense state, and ultimately in this model an ‘initial singularity’ from which time is measured. However, we only have direct evidence of what happened from when the Universe was a second or so old, and the events prior are still open to debate. Using the very latest findings and insights from the field of cosmology, David explores the leading ideas for what happened before this time, focusing on the theory of cosmic inflation as well as alternative ideas of the Universe’s origin.
David Mulryne is a Royal Society University Research Fellow in the Astronomy Unit, School of Physical and Chemical Sciences, Queen Mary University of London. After completing his MSci at Cambridge and PhD at the Astronomy Unit at Queen Mary, David held postdoctoral positions at DAMTP Cambrdige, the Theory Group Imperial, and at Queen Mary, before being awarded his research and proleptic fellowship in 2014. His particular area of expertise is cosmological inflation, a period of rapid expansion thought to occur before the hot big bang, however David also has extensive experience in teaching, outreach and public engagement. He has been a member of various national grant panels and is currently a member of the STFC Astronomy Grants Panel.
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44 Comments
@johndarbyshire6020
02/18/2025 - 2:05 PMYou and others seem to forget that the universe is expanding from an origin. After an explosion from a point, the view from any fragment is the expansion you described, but all this stuff is moving away from an origin. The location where the big bang happened, or is happening, is still there. It hasn't moved.
If we see an apparently spherical region, at whatever distance, which has the same red shift, then it is not really spherical. Einstein forgot that there IS an absolute reference location in the universe. It is at the centre where it has been since the big bang. You can't just forget that, and treat the universe as expanding evenly.
@paulthomas963
02/18/2025 - 2:05 PMCosmic inflation is intellectual chicanery.
It's not science, it's a fudge factor. And without it the Big Bang is impossible.
The impossibility + the JWST data not fitting should make you all admit it's falsified but here we are, science in denial.
@thevikingwarrior
02/18/2025 - 2:05 PMCosmology is absolutely fascinating isn't it?
@thevikingwarrior
02/18/2025 - 2:05 PMCosmologists feel that the expansion of space is due to dark energy overcoming the gravitational pull of matter in the universe. But I have to say that this is not nessicarally true, because although gravity pulls matter together, it does not mean that it pulls space together which matter occupies!
@pponpp-v8i
02/18/2025 - 2:05 PMThere's no way that bucket had 100mln sand grains in it. If it had , surely, you'd need thousand , not hundred buckets of sand to demonstrate the scale of 100bn star galaxy. Not sure what else is not right in this presentation.
@fraMOON635
02/18/2025 - 2:05 PMB.s. cgi does fucko
@fraMOON635
02/18/2025 - 2:05 PMThe pic of the beginning? DO ANYONE GET IT?
a try to find an explaination of the mégaphone ! ! Who understand ? I SAY LIAR.
Any proper teacher around?
@rebwarwar5184
02/18/2025 - 2:05 PMThe universe never had to inflate , it never was as small as a Singularity primeval atom. It was already inflated at the beginning.
@4seiken-594
02/18/2025 - 2:05 PMI watched the entire thing, and the questions I had before starting the video remain unanswered. Who can sate my hunger for answers about this god forsaken topic???
@wessla
02/18/2025 - 2:05 PMThe scale of that radiosphere and the galaxy are way of. It seem to cover over a fraction of the milky way.
It doesn't. It's not even a fragment of a fraction of a fraction.
@meknotewe8155
02/18/2025 - 2:05 PMHas anyone ever thought that maybe the big bang was the other side of a brand new black hole???
@gavbarker8689
02/18/2025 - 2:05 PMI love his accent, Irish + I don't know what, like sylvain guintoli, the motorbike racer, french + middle England (he lives in Derby) I like genealogy and accents.
@richardbeare11
02/18/2025 - 2:05 PMSo, at 59:15, it's as if you're rendering an image starting with a very low resolution, like 1×1 pixel 🖥️. As you increase the resolution incrementally (exponentially – 2×2, 4×4, 8×8, …), more details emerge, and the screen itself also expands exponentially. This process is powered by your city's power plant, which represents the inflaton field, giving you a substantial power budget at the start. These pixels represent the density of space across all points in space.
Your initial power budget allows you to easily add new pixels and expand the screen size. Pixels fill in gaps that would otherwise be empty when increasing the screen size. These new pixels, which represent regions of space, have their colors determined by rolling a weighted dice. This biases their color towards neighboring pixels but introduces slight variations, representing quantum fluctuations in the density of space.
As you keep increasing the resolution and expanding the screen, the power budget starts to deplete. Each new addition consumes more power, and the ability to add new pixels decreases—the power plant isn't able to increase its power output as quickly as it used to. Eventually, you reach a point where you can't afford to power any more new pixels, representing the end of inflation.
At this moment, instead of just stopping, the power plant goes haywire—it becomes unstable! Instead of maintaining the typical 120 volts AC, the voltage shoots up dramatically, causing the screen to heat up intensely, melting the pixels down to a hot, dense plasma. This represents the reheating phase in cosmology, where the remaining potential energy of the inflaton field is converted into particles and radiation, significantly increasing the temperature of the universe.
The power plant eventually catches up and stabilizes – but can no longer supply the expansion of pixels at the same rate. The pixels that melted to plasma begin clumping into regions of higher and lower density, and eventually cool back down as the power plant restabilizes to its nominal voltage. This is analogous to the transition from the hot radiation dominated Universe into our current "cooler" matter-dominated era, filled with clumps of regions of stars and galaxies.
Does this analogy get the gist of it?
@brianmason9803
02/18/2025 - 2:05 PMAre they going to revise all these lectures in light of the latest Webb discoveries?
@bernarddeham4787
02/18/2025 - 2:05 PMCosmology should be renamed Comicsology. Indeed how can you seriously defend a theory that explains not even 5% of the matter in the universe and take dark matter and dark energy like a rabbit out of the magician's hat? Now with the James Webb telescope the problem becomes reality blatant!
@andreaswimmer6864
02/18/2025 - 2:05 PMSo the universe is obese!?
Being stretched in between 😂
@rogerjohnson2562
02/18/2025 - 2:05 PMwow, that 'inflation' passes as 'science' baffles me
@10thmountainsoldier90
02/18/2025 - 2:05 PMRead the Bible. Genesis 1
@getonlygotonly
02/18/2025 - 2:05 PMgod I love experts that can tell me all about the history of the universe but cant tell me for sure how all the water got on our little planet
@juanferbriceno4411
02/18/2025 - 2:05 PMInflation is a bit of fantasy in some ways. Dont know if it is true or not. It assumes way to many things or put in a different way, it is an over engineered idea….These guys are like arcane witches playing with mathematics. however, I commend them for the effort.
@garysarah.middnightspecial
02/18/2025 - 2:05 PMIs it possible to have a big bang in middle of university to see what would happen.
@stephanmayer6191
02/18/2025 - 2:05 PMJust explain to us what happens with any type of bomb , before the bright flash. There you have it.
@Martingray7875
02/18/2025 - 2:05 PMI can save everyone time and tell you what happened before the universe and why the universe was created and how……..GOD
@RobertJackman
02/18/2025 - 2:05 PMHe is a very good speaker. I find the mix of advanced topics and basic ones to be puzzling. He almost assumes that you are familiar with non-Euclidean geometries and Heisenberg's
Uncertainty Principle but sketches out in a very basic way. I kept thinking yes yes but please get on with it and give the topic some depth
@ellysmith5356
02/18/2025 - 2:05 PMThe very worst explanation of inflation I've ever heard
@andys4777
02/18/2025 - 2:05 PMVerbose to the point where it is harmful, meaning that the concepts would have been much easier to understand if he'd use fewer words.
@Dheeraj5373
02/18/2025 - 2:05 PM25:50
You could pick up three points in the space energy diagram and measure their angle, if they add up to 180 universe is flat, if they are more than 180° it is elliptical and if it is less than 180° it is spherical.
Uh intersting isn't it.
This idea I got from here.
Hope I could work on this in future.
Thanks 😊 Royal Institution and happy 225th birthday
@Dheeraj5373
02/18/2025 - 2:05 PM15:40 the way the whole universe is summed is beautiful to watch.
We felt very small in this comparison 😂
@boonraypipatchol7295
02/18/2025 - 2:05 PMFrom beginning of BigBang to the end of the universe.
From beginning of Blackhole to the end of Hawking Radiation.
Are…. Implications of…. Nature….. Reality.
Quantum Information and Quantum Entanglement are Fundamental.
Quantum Mind emerge.. Collection, Pattern of QuInfo and QuEntang.
Quantum Body emerge.. Std.Model emerge, DNA, Protein synthesis.
Mind and Body entanglement.. Consciousness emerge.
Spacetime emerge.. Mass.. Energy.. Wave fn. Decoherence.
Mathematics Emerge.. Intrinsic in the fabric of the emergence.
Holographic Principle..Information Conservation, Energy Conservation
@mrp8811
02/18/2025 - 2:05 PMchaos followed by order. not difficult.
@mrp8811
02/18/2025 - 2:05 PMstatic is the map.
@Peter_Telling
02/18/2025 - 2:05 PMThanks!
@natersoz2
02/18/2025 - 2:05 PMIt that River from Slow Horses?
@olavisepp6833
02/18/2025 - 2:05 PMzbc
@georgesos
02/18/2025 - 2:05 PMInhomogeneity presupposes the existence of something bigger than the universe.
So…..wtf r we talking about?
@georgesos
02/18/2025 - 2:05 PMTLTR : we dont know.
@fl00d69
02/18/2025 - 2:05 PMI found this guy to be really annoying.
@CrashExhibition
02/18/2025 - 2:05 PMI mean this with no sarcasm or hate: what an interesting accent. At times you sounded like you were from Northern Ireland, but at others almost RP or very upper class London, and it mixes in such an interesting way.
@BobbyClements
02/18/2025 - 2:05 PMWhat if the expansion ‘stretching’ is like watching 3 dots on our stomach expand as we inhale?
We think the universe has been expanding since the beginning of the Big Bang but what if were looking at a single inhale this whole time? let's say it takes 15 billion years, on the human timescale for the universe to take half of a single breath (how many times does the average human breathe per lifetime?) perhaps we cannot get the full answer until we can measure the other half of that breath from the universe and the only way to do that is by a dying ourselves, or maybe by having a near death experience – while not only having to remember what you’ve learned while “dreaming” but also have the ability to find the pattern in the numbers.
Everything we’ve come to know and love is like a compound clip in a Final Cut Pro Timeline and our whole life is a single pixel on a random location of a frame. We don’t know nothing because we can’t know anything without having full access to the full contents of the project.
@sleepEasy2
02/18/2025 - 2:05 PMIt all began at the bottom of another black ⚫ hole. 😅 I'm just putting it out there.
@mitseraffej5812
02/18/2025 - 2:05 PM0:52 “ Everything in the universe is getting further and further away from everything else”.
On a more human scale my socket set is absolute proof of this.
@alexmirza5210
02/18/2025 - 2:05 PMOh David got nervous when he said that there were about 400 billion stars in the observable universe when he meant 400 billion galaxies. Still mind-boggling, but wrong oops. The sand bucket was a great idea to help imagine.
@JuanTripMusic
02/18/2025 - 2:05 PMThe lazer's on ! Where's the party ??
@temptemp563
02/18/2025 - 2:05 PMIf the universe was initially non-uniform, wouldn't that be strange and demand explanation? Surely dis-uniformities would require a cause, whereas uniformity simply requires things to be left alone … so I'm always going to be confused by this inflation debate I think.