How do we know everything about universe with such precision?

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I understand that we build models and do calculations but aren’t there any potential errors/assumptions? That accumulate over multiple calculations and grow bigger the further we go back or over distance?
I.e. “At approximately 10−37 seconds into the expansion, a phase transition caused a cosmic inflation, during which the universe grew exponentially, unconstrained by the light speed invariance, and temperatures dropped by a factor of 100,000.”

In: Physics

11 Answers

Anonymous 0 Comments

We aren’t really measuring these things, we’re calculating and simulating them based on known physics and probable theories. It’s still all conjecture, though, and yes they could easily be off by orders of magnitude, if not entirely wrong. Also, the first few moments are currently entirely unknown to us because physics as we know it simply breaks down.

When these things are discussed and documented for non-physicists though, adding all the caveats of “according to XYZ theory/model” doesn’t really help understanding, especially if prevailing theories are well accepted.

Astronomy in general deals with such large numbers usually that what an astronomer might consider pretty close is actually off by several light years. The fact we can even have a pretty good guess at what happened in the first few seconds of the universe is amazing.

Anonymous 0 Comments

There’s always potential errors. A really big part of science is in quantifying and understanding all the possible sources of error, so that at best you can minimise them, and at worst understand what the confidence in your result is.

As an example, the current estimate for the age of the universe is 13.787±0.020 billion years. The “±0.020” part is just as important as the “13.787” part.

Anonymous 0 Comments

[Warning, I’m only a university physics student taking some higher-level undergrad astronomy courses]

the way we see the universe now is dependant on how the universe acted when it first formed.

If you see a car flipped over on the road, that tells you a car was driving, and then crashed.

In the same way, we look out and see for example a given ratio of protons to neutrons in our universe. We know from experimental data that neutrons can interact with some other given elementary particle at a certain temperature. For us to have the ratio of protons to neutrons that we have today, the universe would have to have a temperature shift at those critical moments in it’s early stages.

Thats just one example, but most all of cosmology is a fascinating puzzle of reversing effect to find cause.

Anonymous 0 Comments

We don’t know everything about the universe. If we did we didn’t need scientists. The only thing we do know with “such precision” is that we barely know anything about the universe

Anonymous 0 Comments

We don’t, not even close. There are a handful of examples of things like universal constants where we know the *exact* number, but far more where we *don’t*. I can’t sit here and list them all out for you, but just know that we very much do NOT know everything in the universe *at* *all,* let alone with any amount of precision. I mean we can’t even date ancient artifacts from a few thousand years ago without at least some range of error.

Anonymous 0 Comments

If you look at the wikipedia article where you got that quote from, you’ll see that the quote is citing a 2005 student website from Georgia State University, which itself was citing a 1994 article in a National Geographic Magazine written by an astronomer who was doing a PR piece on a new telescope in Hawaii.

A lot of wikipedia physics articles suffer from, at best:

1) Being based on non-technical publications that were written to be interesting to people who know nothing about physics, rather than accurate.

2) Being based on old, outdated theories – much of what’s on wikipedia is >30 years out of date.

3) Being based on what is being taught at the college undergraduate level. While stuff in this category is better than #1, stuff being taught at this level is still dramatically oversimplified or incomplete in order to be comprehensible to undergrad students.

A fundamental problem with physics is that its non-intuitive and stupid. You can’t just take someone who has no knowledge of physics, dump PhD level physics on them and expect them to comprehend any of it. To get around this, physics is always taught at an overly simplistic but sort of correct level that gets more accurate as you get higher up. One of the problems with that is as you get higher up and the physics gets more accurate, you’re continuously told “ya what you learned previously was close enough for the level you were at before, but its all wrong…”

You’re probably more familiar with this process because its also how math is taught. For example, when you were in elementary school you were probably taught that you could not subtract a smaller number from a bigger number when you were first learning math. Then you were taught that you could the next year. You were also probably taught that 4/3 is “1 remainder 1” when you were first learning division. The next year you were taught it was 1 and 1/3. Then the year after that you were taught it is 1.3333~. Physics is taught the same way, except the concepts are more complex and, as a result, the previous year’s teachings are generally more wrong.

You also have to keep in mind that when you enter into post-grad physics, you’re entering a world in which the cost of conducting basic research is very high and the results can be used to develop nuclear weapons and cutting edge products. The result of this is that governments and large companies have their own physics models that are both non-public and more accurate than what will be taught at any university. So, for example, a scientist working at Los Alamos or Nvidia will have a better understanding of the physics areas that they’re working on than most university professors will.

So to answer your question – the quote that ended up being presented as a hard fact on wikipedia was never meant to be taken literally. Its just a random factoid from a 30 year old pop-sci magazine that was being used to illustrate how old the stuff a telescope in Hawaii was looking at. That is, at best, par for the course for wikipedia and you should never take physics articles on wikipedia as being anything more than what they are – which is simplistic articles that are being written to be interesting and comprehensible to people who know little about the underlying subject.

Anonymous 0 Comments

>but aren’t there any potential errors/assumptions?

Yes, tons of them. This is why the theories and models keep changing as we gather new data.

Anonymous 0 Comments

The first thing is we don’t know everything about the universe. There are many many things we don’t know. We are still making discoveries, some of which voids previously “known” theories.

Anonymous 0 Comments

Very few people that are actually doing the research present their work as fact and they make judicious use of qualifying statements. That’s across most scientific fields.

What scientists can’t control is how third parties in the media present their research.

Anonymous 0 Comments

errors might always happen, but if your work is reviewed by peers, it usually mean its pretty good.

for space and the universe, we dont know much actually, we mostly have approximations. accurate approximations but still approximations.

tho i wouldnt suggest taking your infos from wikipedia, which is, at best, incomplete, at worst, completely wrong. but its still better than reddit for sure.