37

I think that your thought process is flawed in that you assume that by drastically increasing the temperature you are guaranteed to get heavy elements. As odd as this may sound, this isn't the case (especially during the Big Bang Nucleosynthesis (BBN)) for a few reasons. In fact, if you took a hydrogen-only star and made it go supernova, you wouldn't get ...


15

We don't know what's on the other side of the Big Bang, if anything at all. The Big Bang theory as well as the rest of physics is agnostic on this possibility. During the time period after the Big Bang, the entire universe was basically in a hot, dense plasma state; any physical signals propagating from a period before the Big Bang that could potentially ...


15

The correct version of your first sentence would be something like: Given our knowledge and the standard cosmological model, we estimate that the age of the universe is about 13.7 billion years old. Every work quotes slightly different values for the age, depending on methods, observations used, assumptions, etc. As example, the first results from the ...


13

This is a great question. I know of a couple of really big things about inflation people want to be able to nail down by using the cosmic microwave background. The first is measuring what are known as E- and B- modes, which are the curl-free and divergence-free components to the modes of cmb radiation: Essentially, measuring large scale Gaussian B-modes ...


11

tl;dr: Your field of view would cover roughly one square centimeter of the sky at that time, and you would observe roughly 50 billionths of the observable Universe. You can't really… With photons, you will never be able to see further back than to recombination, when the Universe was 380,000 yr old, because until then, the free electrons made is opaque to ...


8

This is really simple once you get it: The usual analogy here is to look at the surface of a balloon (which is a surface in 3D space, rather than 3D space itself, but the analogy still works) A partially inflated balloon has tight curvature, but as it is inflated, the curve decreases - the surface at any point becomes 'flatter' From an article on this ...


8

I...think you've got it backwards? Slow-roll inflation is alive and well, unlike models which involve tunneling between two vacua. The model of inflation first proposed by Alan Guth back in 1980 was a tunneling model. But it had a serious problem: it didn't reheat. Tunneling from a false vacuum to a true one (or a lower-energy false one) wouldn't release any ...


7

Gravitational waves from the big bang may be "heard" but not by LIGO. The waves emitted at or around the inflationary epoch of the big bang are expected to be at much lower frequencies (milli-Hz or lower) than those announced today by LIGO. There are various sources of noise that make LIGO insensitive to GWs at frequencies below about 10 Hz. It will take ...


7

Quick answer: Because they didn't entered our event horizon. Some never will. And some will move out of our event horizon - their last photons that'll be received here being sent right now. Let's do some fact checks first: [...]the galaxies that are now at the 'edge' (not visible theoretically) must have been (at some point in time) at place around ...


6

If you think on Big Bang as an explosion IN space, you are plain wrong. It was not. It was an explosion OF space itself. And time, for that matter. What happened before the big bang according to these scientists? Common misconception. There is no "before". Time starts at Big Bang. How on earth can it be a blast , because obv like any blast it should ...


5

What the video is clumsily alluding to is that the universe was very much smaller than it is today. However, if the universe is infinite, then it was still infinite at all times in the past. All one can say is that the density was much higher. Sometimes commentators are more precise. One can define a size scale for the currently observable universe and ask ...


4

Lithium, along with Hydrogen and Helium, was one of the 3 elements created in the Big Bang. Thus, it should exist to some part in any star that hasn't burnt all of it out, and as mentioned, it's not an easy thing to do. Population III stars are expected to contain Lithium, and Beryllium as well. The amount, however, is not particularly high.


4

It is unfortunate that the usual poor journalism labels the growth of the black hole as "inexplicable" and then further down in the article refers to some possible explanations. The basic problem is a growth timescale one. Radiation pressure introduces a negative feedback, such that there is a "theoretical" maximum for spherical accretion called the ...


4

To answer your second question first: Yes, antimatter does exist in the same space as matter. In fact, the universe creates antimatter (and an equal amount of matter) every day as a matter of course in events like lightning strikes and supernovae, and even in certain nuclear decays. Humans create it in particle accelerators for research and for commercial/...


4

The current model of cosmology starting with the Big Bang states that all spatial and temporal dimensions (Length, width, height, and time) as well as the four fundamental forces originated from a single point. With time starting with the big bang, there was no 'before', just like there was no up or down, no gravity or electromagnetism. There was no ...


4

We don't is the simple answer. However it is difficult to test any such theory and so it veers in the direction of metaphysics. But one theory is that the physics in our neighbourhood changed (a state change, much like a change in the quantum state of a molecule migh lead to a release of energy as light) and that the energy released caused the early rapid ...


4

WHY implies a reason, which is venturing in to the religious realm. The circumstances under which an event such as the Big Bang occurs are guess work at best. Since the Big Bang is a singularity from which time itself started there is no real before the big bang. That's the first problem. The second is that because of the spatial singular nature of the big ...


4

Nowadays, the universe is mostly ionized, and transparent. Transparent means that photons are able to travel long distances. So there comes the confusion: How could it be that recombination made the Universe transparent, and reionization keep it transparent? After the Big Bang we had a very small Universe, filled with ionized matter. That amount of ...


4

We don't have theories that can describe the big bang (or whatever happened) properly so we can't say anything definite about the big bang itself, let alone if/what was before it. We would need (at a minimum) something like a quantum field theory for gravity and we don't have one yet. We've no reason to think that's all we'd need. It's not even possible (...


4

Yes, and indeed it did. For some stars. Some first stars were close to us, some were far away. The light from the ones that were very far away has yet to reach us, while the light from the ones that were close to us, reached us in the past; if we look today at their location, we no longer see first stars, but instead see evolved galaxies. On the other hand,...


4

The very first stars were probably, massive, ultraluminous, and very short-lived. So if they were formed 400 million years after the big bang, then they would have ceased to exist only a few million years later. Given that, if we wish to observe the first stars, then we have to look at the light from galaxies that has been travelling for 13.3 billion years ...


4

In principle yes, in practice no. As seen in the temperature power spectrum below, the Planck satellite detects power (i.e. "a signal") even on the smallest probed scales, which is a few arcminutes. Fig. 1 from Planck Collaboration et al. (2016) with my own approximate corresponding angles annotated in red. The smallest scale shown in the figure is $\ell =...


4

We can, after making some approximations, trace the movements and locations of the matter in the universe back in time, using the laws of physics (mainly general relativity). At the moment we see a certain density of matter which is, on a large enough scale, expanding uniformly -- as if space were being blown up so that every bit of it doubles in size ...


4

I assume you're referring to the recent press release about the quasar J043947.08+163415.7, observed recently using Hubble. The paper about the observations details how the authors measured the distance to the quasar, by calculating its redshift, a quantity that describes how the wavelength of light appears to change based on whether the object is moving ...


4

According to Mashian & Loeb (2016), one possibility is that planet formation may have occurred around carbon-enhanced metal poor (CEMP) stars in the early universe. The paper focuses on CEMP-no stars as the most metal-poor CEMP stars mostly fall into this category. CEMP-no stars are thought to form from material polluted by supernova ejecta from ...


3

Given chaos theory, things could have been different. Given the laws of physics, there are limits to how much difference there could have been. To put it bluntly, a subatomic particle could have zigged instead of zagging, causing a fusion event that led to the formation of a star not to take place in one spot but another. But it would not prevent stars from ...


3

In early times of galaxy formation you would have seen a sky similar to this Hubble Extreme Deep Field image. A sky filled with small, irregularly shaped, young galaxies and galaxy predecessor fragments (sub-galaxies). Galaxies probably formed bottom-up from smaller fragments. Further back in time it would have been dark. Hydrogen clouds would begin to ...


3

We know that intelligent life exists on one planet. We do not fully understand the processes by which life (a) starts and (b) becomes intelligent. Therefore, the probability of these things happening elsewhere ranges from 1 to as close-to-zero as needs to be to ensure we are the first and perhaps only intelligent life in the universe. Therefore the answer ...


3

Your question is one that bothered cosmologists for a long time, how do you get clumps of matter out of a smooth initial condition, in the time allowed? It was long understood that a perfectly smooth matter distribution could not be maintained forever, because gravity creates instabilities-- the smallest overdensity in one region would tend, over time, to ...


3

Our knowledge of planet formation processes comes from theoretical work and is supported by observations. I'm going to give it my take based on that. On the lower mass end of the planet distribution, starting from comets up to Super-Earths/Mini-Neptunes one needs a high number of rock-forming elements in order to build rocky worlds. Without high ...


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