Study reveals new details on what happened in the first microsecond of Big Bang | Hacker News Reader

Study reveals new details on what happened in the first microsecond of Big Bang

phys.org

48 pointsdnetesn64 comments

I don’t have any physics background so maybe this doesn’t make sense but I’m betting someone can answer.

If time is relative, what is a microsecond when there is nothing to relate it to? What does time dilation do to a microsecond when you’re at the center of a space with the mass of the entire universe?

I’m struggling to interpret a microsecond (or any other unit of time) near the boundary at which time came into existence.

Physics is so broken that they cant even explain galaxy rotation (dark matter is a failure) but the media is reporting with authority what was happening microseconds after the “big bang”.

Hard pass.

I expect you're uninformed but I don't know enough to prove it. Either way, I'm annoyed that you've been downvoted without a single reply. I'd like to know if/why you're actually wrong.

It's true that physics can't explain galaxy rotation (speaking as someone who recently taught elementary cosmology at a good university). I don't know whether that has much to do with the big bang though. I expect the downvotes are for non sequitur.

This is just how science works: we find evidence for some things, and we don't have evidence for others, so the things we can explain is limited to what we can back up. For example, we don't know why people yawn but that doesn't mean that we can't explain in detail how sedatives work.

But we also can’t explain in detail how sedatives work... We have no idea whatsoever how most classes of sleeping meds function.

We have a fairly good idea how most sedatives work and which receptors they bind to. But even when we don't, I am not sure what your point is: even when we know some things there are still things we can't explain yet…which was basically what I said?

You are essentially correct - popular scientism outlets do not have an appropriate degree of humility when reporting on things like this. However, the physicists themselves tend to have a good understanding of the caveats and context of their predictions, even if this doesn’t generally end up getting communicated to consumers.

"time is relative" has a very particular meaning, it's not just a "proverb". It means (in the simpler special relativity) that how fast time seemingly progresses is relative to the difference in velocities of two different inertial frames ("things that move at the same velocity and without external forces").

The only thing that special relativity assumes about flow of time in general is that within each of these frames, the speed of light is the same. This also means that you will always observe time progressing in any inertial frame, unless your relative velocity to it is the speed of light.

I have a hard time believing it’s possible to know such a thing so specific without some kind of supernatural knowledge, there’s simply too many assumptions that all have to be correct. It almost feels arrogant, but they even admit it: “Their findings provide a piece of the puzzle to the evolution of the universe, as we know it today”.

This is why the researchers have to proceed with extreme caution. All of the assumptions have to be testable through consequences that are observable in our world.

It's always struck me as odd that "arrogance" is applied to science, which is based on the ultimate humility of laying all of our cards on the table and agreeing to accept the consequences of empirical evidence that might overturn our beliefs.

In consequence, supernatural knowledge has already produced a plurality of definitive answers. That strikes me as arrogant.

It's like the Drake equation. So many unknown unknowns even guessing is utterly useless.

I wish scientists and reporters made it more clear that science, the process, can never know when it is right about something.

The Scientific Process can only ever know when it's wrong.

A scientist can gain confidence about their theory's correctness, but they can never be assured of it. A single discovery could completely overturn all of the understanding that appeared so rock solid the day before.

I'm just saying that the headline should reflect this.

"Scientists, and the process of science generally, who can only prove things wrong and can never be entirely sure if they are right, have produced a study revealing new details on what happened during the first microsecond of the Big Bang."

Imagine if people followed your request. How many times would you read that disclaimer before you got sick of it?

less tired than I am seeing things stated as fact, as if we know for sure, when we don't.

less tired than I am explaining this to people who don't understand it.

and the wording would be more like changing "Scientists now know..." to "Scientists now believe..."

Now do one microsecond before.

I know you're joking, but "before" the Big Bang doesn't really make sense.

If so, then "first microsecond of the Big Bang" also doesn't make sense. And that may be the point of the above comment.

The only time reference is the one within the universe that is doing the banging, and within that universe, time has no beginning, right? Every microsecond has another microsecond before it.

Unless you’re at t0. It doesn’t have to have a before.

Not really? It makes sense to ask what happens in the first minute of The Matrix film, but it doesn’t really make sense to ask what happened one minute before that. That particular domain (a specific film) has a pretty clear “beginning time” and apparently this model of the Universe does as well.

Have you seen Memento? It's a murder mystery that scrambles time. Much better than The Matrix.

There are two interwoven threads in the film, one in colour and the other in black-and-white. The B+W scenes are in chronological order, the colour scenes run backward in time. Colour and B+W scenes alternate. They meet up at the end - the murder scene, which in any sane movie would be near the beginning.

The protagonist has lost his memory, as a result of a bang on the head during the murder; he has no idea what happened "before the beginning".

There can be a point in time where you can't go further back - all directions point to the future - in the same way that there's a point on Earth where you can't go further North - all directions point South.

Yes, I believe it's called God. Maybe one day we can find a formula!

Science will never say that. Maybe they want to see him or something.

That would be very helpful.

Do you think that belief would make any sense in that case?

Sure there's even a story about that called Hell is the Absence of God.

> Maybe one day we can find a formula!

It'd be horribly depressing.

The big bang is not a complete cosmological model and does not necessarily preclude things happening before it.

It isn't a complete model, but it's the best one we've got and the most universally agreed upon.

It is, but it's not universally agreed that it's the first event of reality. I think most remain pretty agnostic on that point.

It might make sense if you subscribe to the idea of conformal cyclic cosmology. Where the big bang marks the transition between eons

https://en.m.wikipedia.org/wiki/Conformal_cyclic_cosmology

Could it be we create and always have the big bang by blowing shit up in a particle accelerator, and that is the great filter not just for us, but the rest of the universe since it just starts over?

In conformal cyclic cosmology, there are no big bangs.

Once everything in the old universe has been reduced to photons, and all the black holes have evaporated, the universe loses its sense of scale, and resumes operation as a universe the size of a grapefruit (or the size of the earth - I don't think it matters).

I don't know how Penfold thinks this resizing is supposed to happen, for example whether it's instantaneous or a slow process.

I'd love to have a few beers with Penfold; a lot of what he thinks about isn't maths or cosmology, and isn't all fit for publication, but I imagine it must be very interesting.

I condensed my post for brevity, there's no exact defined boundary between aeons or how that transition exactly occurs.

One could arguably say it's when there are no fermions from the previous one anymore, but that can be contested.

Not necessarily. I think the physics consensus is they don't quite know if "before the Big Bang" does or doesn't makes sense.

"Fluent"? Like water? I think the writer perhaps meant "fluid".

I found the article disappointing; apart from revealing that the for the first microsecond the universe consisted of quark-gluon plasma, which subsequently turned into hadrons, there's no substance.

And zero "new details" - I knew about quark-gluon plasma.

I think that title is linkbait.

A lot of sensible comments are getting downvoted here without any replies to them.

Welcome to HN in the last 3-4 years.

We have studied a substance called quark-gluon plasma that was the only matter, which existed during the first microsecond of Big Bang. Our results tell us a unique story of how the plasma evolved in the early stage of the universe...

Is this stuff at all... non-safe? I mean, could one use it to recreate the big-bang in a lab? It's hard to conceptualize how something like a "bang" happens without a catalyst, so couldn't the catalyst be scientists f**ed up?

You'd need to pour in insane amounts of energy. The people who build particle accelerators are trying to do exactly that!

I can understand that there was a Big Bang. But why does time necessarily have to start at that point?

Why not just assume that everything lay dormant for a very long time, maybe forever, before Big Bang. And then Big Bang happened. Like some quantum fluctuation perhaps.

Just because we don't know how we could measure time before Big Bang doesn't mean time didn't 'exist" before it, does it?

Check Conformal Cyclic Cosmology: https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology

You're right. The Big Bang theory really only concerns itself with what happens starting at around 10^−43 seconds after the presumed singularity that started the universe. That presumed singularity is just a consequence of running General Relativity backwards, and we know that quantum effects are also important at these kinds of insane energy densities, so the singularity can be thought of as a placeholder, until something better comes along. (A complete theory of Quantum Gravity would help a lot.)

I think we don't know. But even if time or anything else existed before the Big Bang, we have seemingly no evidence of it, no reasonable expectation we could ever have any evidence of it, or any way to measure or deduce anything about it. It might as well not exist, for all intents and purposes it no longer does if it ever did.

By contrast, we _do_ see evidence of the Big Bang itself, and our best models today are that everything we see is evidence of (and a product of) that Big Bang.

Additionally, the space expansion aspect of the Big Bang means that space itself in some sense came from the Big Bang. Everything we see was indescribably compacted at that point and then expanded from there, over time.

So if there was anything before the Big Bang, it wasn't space as we know it and it didn't have any knowable effect on the universe we see.

In conclusion, if you have nothing, in no space, does time even mean anything?

How certain are we of this? Why could the big bang have not happened in space, at a point in some time continuum that started before the event itself? Why could it not be a relatively local phenomenon that we simply cannot observe beyond?

I believe that's possible, but seems equivalent to there being multiple universes, none of which we can see.

> if you have nothing, in no space, does time even mean anything?

True. But I have hard time just thinking about what time means as a physical entity in our current universe. If nothing changes, does Time stop existing?

I'd say that if everything stops changing, then time is either meaningless or doesn't exist (I think depending on whatever stances are in your view of philosophy, you can pick either).

Well let's say that something is happening at a certain pace. Then it starts slowing down. The reason we can say it is "slowing down" is because we have the notion of time that exists regardless of how fast things are changing, or not.

So if nothing is happening I would think it means that things are happening at zero speed. Again we can say the speed is zero, because we have the notion of time that doesn't change juts because things slow down.

> But why does time necessarily have to start at that point?

Because that's just how the math works. It's just like asking what's north of the north pole, or what if you go more down if you are in the center of the earth.

The passage of time can't be measured in the absence of matter (with mass). "Particles" that whizz along at the speed of light can't be used to measure the passage of time.

So if there's nothing in the universe but photons, the passage of time makes no difference to anything in the universe; so there's grounds for saying that time exists.

Something can only be said to be "real" if its existence or non-existence makes a difference to something else.

/me is not a physicist or a mathematician; just regurgitating what I've read in popsci books and articles.

time is related to space (spacetime) so time essentially has only a meaning with inflation, hence when inflation started, essentially time started. But that doesn't mean existence isn't eternal which is independent of time ( depending on how you think of time )

I have always have one confusion towards big bang theory.

the evidence it has suggests that matter is moving away from a central location but there is no evidence at the size and time of this central position.

so how could bing bang theory claim that its original size was in milimeters as opposed to lightyears?

A more elaborate example:

consider this, we have a water balloon diameter 5 cm. I threw it towards a wall and it burst at time t = 10. from the observing that water flow at time t= 12 and t =13. i can say water originated from a single location. and at time t =10, water was in 5 cm balloon shaped form. at time t=9, it was in 3 cm balloon form, at time t=2, water was concentrated in form of 2 mm ballon. and so on.

does bing bang theory suffers from the same issue?

things aren't moving away, space is inflating, it has the odd property ( often explained like the surface of a balloon inflating but in 3d) that anywhere you are you are at the "center" of the universe with everything inflating away from you.

There was no central location. As far as anyone can tell, the universe was always infinite and has been expanding at every point for all time. It's pretty hard to wrap your head around. References to sizes are probably the size of the "observable universe", which is basically the parts from which light is able to reach Earth. It might help to think of those more as ways to measure the expansion than the size of any actual object.

I think the name "big bang" does the idea a disservice. It's not an explosion moving out from a central point.

My popular-science understanding of this goes like this:

So Einstein has this cool theory where space and time don't work like we think they do - they turn out to be a unified geometry: spacetime.

Since we are very small and move very very slowly[1], our intuition for how spacetime works is way off. It works a lot different from what our slow experience intuitions suggest. And the pictures we draw ourselves in our imagination when we imagine all of space are way off.

Space can have a curvature [2]. The curvature basically means that things moving in the straightest lines that they can move closer together or further apart. This turns out to describe gravity well.

The mathematics is thorny, but when we make the simplest possible models of the whole universe (sort of like an ant modelling the earth as a sphere because he knows it has a curved surface) we find that the entire space has a beginning and that the space part of it has been growing larger since then.

So it's like a 2d ant living on an inflating balloon. At some point the balloon was a small "point" and everything on the surface of the balloon is busy "moving away" from everything else as the balloon expands.

The big bang is what we call the small hot part near the beginning when space was very small (even in our terms of experience)

[1] Natural speeds are fractions of the speed of light and natural distances are distances related to how far light travels in a unit of time suited to our perception.

So, to the moon is a good kind of distance if you live at a second kind of level of perception, and around the earth about 8 times a second is a natural speed.

[2](without being embedded in a bigger flat space)

Eternal Inflation models of the universe have a really interesting answer to that question. It seems to be more mainstream than the conformal cyclic cosmology a sibling mentioned (which is also very neat).

Inflation models may be more mainstream; unfortunately, the evidence for inflation is rather thin. Inflation is a "theory" that purports to explain the unexpected smoothness of the cosmic microwave background.

It is not a good theory, because it makes no predictions that are testable, even in principle. I think the unexpected smoothness of the CMB is evidence that the big bang theory is not correct; fixing the big bang theory by bolting on inflation looks to me like mathematical voodoo.

I’ve never understood the claim that CMB homogeneity implies those regions need to be causally connected in a traditional sense; they might be “causally connected” by the fact that they obey the same physics. Even if you don’t accept that the physical laws themselves could be spread over a spacelike boundary, it could at least appear that way due to selection rules (the same way entanglement collapse can appear superluminal without being so under MWI).

Big bang is also just an reverse-extrapolation from the fact that the universe is expanding.

The universe expanding is also just another guess based on the fact that the light is red.

We also have all these weird guesses with dark matter and energy.

It all sounds flimsy... But to be fair this is probably the most difficult subject to tackle.

We are not due for a physic reckoning yet. We will need to probably wait for another 100 year (like a reckoning when we are convinced that Newtonian is inaccurate).

I think the reckoning will come when our technology is advanced enough to perform physic experiments on other planets, and we will see that some of our theories (especially around gravity) are wrong.

Right now we just assume gravity on Jupiter, for example, work in the same way like gravity on earth.

Another aspect is that our technology may be good enough to measure smaller particles or detect a very weak gravity force in particles.

Neat!

Time is only the relativistic motion of measurable phenomena. We can’t know what we can’t measure, it is perhaps possible that things “happen/happened” outside of the limits of what we can measure and extrapolate from measurement. We will never know what we can’t know. I would argue.

Care to explain the - points?

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