PBS Space Time
1 HN recommender · recommended in 4 months, 2020–2024
13:34 · 2.5M views · Jul 18, 2019
A PBS Space Time episode asking whether time began at the Big Bang. It explains that the Big Bang is not what most people were taught and what 'start' of the universe really means.
Used as a go-to reference for cosmology questions about the beginning of time and the universe's scale.
4 comments from Hacker News
I keep a Google Document of these to share just in case people ask about my YouTube interests. I Actually Watched All of Them I have actually watched ALL of the videos on these channels and I don’t even feel bad about it :-) I actually like new videos from some of the ones below (like NativLang, for example) but they maybe don’t hold up in the early videos. - Space Time: PBS Physics, sooo good -- [LINK] -- Great first video: this video - Lindsay Ellis: Really, really intelligent video essays about film and culture -- [LINK] -- Great First Video: [LINK] - Periodic Videos: Chemistry, including a video for every element -- [LINK] -- Great first video (obviously): [LINK] Other Math and Science - 3Blue1Brown: Amazing math visualizations -- [LINK] -- Great first video, how e^pi*i works: [LINK] - NumberPhile: Fun math videos -- [LINK] -- Great first video: [LINK] - PBS Eons: Biology! -- [LINK] -- Great first video: [LINK] - PBS Infinite Series: Math math math, really really hard math -- [LINK] -- Great first video: [LINK] - SciShow: Science! More poppy but fun -- [LINK] -- Silly first show: [LINK] -- Actual physics: [LINK] - VSauce: Science-y? -- [LINK] -- Great first video: [LINK] - Practical Engineering: -- [LINK] -- Great first video: [LINK] Other Humanities - Alliterative: Connections via language -- [LINK] -- Great first video about gin and gimlets: [LINK] - Bon Appetit: Such fun food stuff! -- Gourmet Makes: [LINK] -- It’s Alive: [LINK] - Masaman: Genetics and human migration (an
It was my understanding that physicists have never claimed that the big bang happened. That the big bang itself isn’t really part of the theory at all and that its simply a singularity point, but that some moments before that point, ohysics as we know it breaks down, so we don’t know what happened before and therefore do ‘t know if there was a bang or not, just that after that time, things happened that we can measure. Put another way, the big bang theory doesn’t include the big bang itself (the something from nothing part) but is about the inflation and expansion of the universe. Here are some PBS Space Time videos on the subject: Why the big bang definitely happened: [LINK] Did time start at the big bang: this video Whats wrong with the big bang theory: [LINK] “In the beginning, there was nothing, which exploded”, now, a lot of non-scientists like to repeat this statement, but no credible scientist has ever said this, nor believes it. So its unfortunate that this statement is used to deride the big bang theory. The big bang describes a series of events that happened to the universe following its existence in an extremely hot, dense state. We have a ton of evidence that the universe was once in such a state. Perhaps our understanding of this state will eventually lead to a theory of the origin of the universe, but the big bang theory as it stands does not claim to explain such an origin. — Matt O’Dowd, PBS Space Time
> Well, no. The density in the observed universe is used to extrapolate the number of galaxies in the non-observed universe. The size of that universe is extrapolated from the rate of expansion and the time since the big bang. > We may not know the exact size at the start, but we know it was infinitesimally smaller than it is today. So the size of the initial universe isn't a big factor in the equations about how big it likely is today. Weather it started as a few centimeters across or a few thousand light years across, both are functionally zero compared to the current size. Most things you're saying are correctly rooted except for what's beyond the observable universe. I'm not sure why the staunch belief that you can confidently claim this. To be clear, you aren't provably wrong - likewise not provably right either. The replies to you are just fine, they represent a significant portion of the scientific community that says our universe is likely infinitely big and that, possibly, the big bang was infinitely small, yet still, still infinitely large. An infinite expanding into infinite still results not knowing what's out there. PBS Space time talks about it in terms of "scale factor"[0] instead of absolute diameter. Still, these are all debatable theories, so your take _could_ be valid, but generally, it points infinitely large. [0] this video
> wouldn't it make more sense that time actually stretches infinitely the further back we go, thus nullifying the concept of a beginning? Matt from PBS space time covered this here. this video