In 2023, yeah, but remember that it isn't in 2023 that the association was made.
Tritium watches used to be a much bigger deal some decades back, as you could actually use the thing in the dark. Subsequent to that, battery-powered digital watches with a light became common, and then a lot of people just moved to using a cell phone to know the time.
As the linked WP article details, uranium glass also used to be more-common prior to the government locking up a lot of supplies of uranium. I've only seen uranium glass in person in museums, and in general, plastic has displaced a lot of glassware today.
Tritium is also still very popular for firearm night sights. And I'm sure some radium painted one used to be as well. The night sights on my SKS may have been radium paint or just regular phosporescent paint, or may have had tritium vials that fell off.
For a while there was a full set of uranium glassware in my local antique mall for sale but I think someone bought it.
So, this is a basic misunderstanding of gravity and acceleration. The measure of Gs is the exact measure of how fast the acceleration is.
This is just like asking if it would be comfortable to survive 100 C if the temperature was cold enough.
There is no difference between acceleration and gravity. If locked into an elevator, you wouldn’t be able to tell with certainty if the elevator started going up, or someone had just turned the gravity of the planet up to make you heavier somehow. If the elevator suddenly dropped in freefall, you would not be able to tell if it was the elevator moving down, or someone had simply turned gravity off somehow. This is part of Einstein’s Special Relativity.
I'm having a feeling it's a combination of other stuff mentioned here like radium, which was then put on The Simpsons and then that's what everyone got the idea from. They made nuclear waste a green liquid and that's the cultural zeitgeist there, probably.
I assumed that once we decided what a second was, that’s what we’re going off of for that 13 billion year assessment.
I guess that’s mostly correct from what I can find online.
From the point of the big bang or creation or whatever, time has been progressing second by second for 13.7 billion years.
With the consistency of time measurement scientists use, it seems like that’s why they use conventional standards of time to measure how long the universe has been around.
From my understanding, yeah kinda. Will preface this by saying I’m not an astrophysicist in even the broadest sense.
But for time to exist at all, we have to assume there was a zero. And seeing as time is a measure of space, if time was zero, then space was too.
We can also ‘see’ the age of the universe. As we can see the earliest cosmic soup behind our stars, and through red shift (the way light shifts it’s wavelength over time) can calculate the age of this background to 13 billion years. So we can say the age of the universe was 13 billion years ago (relative to our viewing angle of our telescopes.)
We also know that even though that light itself took 13 billion years to reach us, The universe, and space it occupies, is expanding and we theorise that it could be as much as 89 billion light years wide. This doesn’t mean the universe is now 89 billion years old though. If you drew on a balloon and blew it up, the drawing would get bigger but there wouldnt suddenly be more ink. It’s just expanded in all directions.
We also know that space and time is affected by gravity. Space shrinks around black holes, and so does time. It’s not a clean straight line, but waves, stretches and curves as it is affected by the masses around it. From the relative positions of these black holes time and space will still appear the same and light will still travel at the same speed, it will still cross the same distance even though that distance has been compressed.
In other words from an outsider looking in it would appear that light has slowed down, and from an insider looking out it would seem that the universe outside is moving faster than it does to us on earth but this is warping nature of time and space. It doesn’t make the universe older or younger, It makes the time it took light to reach them appear different.
So for a person living in a black hole today, the red shifted light of the cosmic microwave background may look much much older, or may not have reached them yet as space has compressed, and as such the background is also further away (in raw space) and the time would be older. But thats relative to them and not ACTUALLY longer ago. Only because we’re still measuring that time scale in earth time units from our perspective in this conversation.
When I say living in a black hole I mean off the edge of the event horizon where time and space can still work according to our known principles of course!
Astrophysicists in this thread please correct me. This is a layman’s attempt at an ELI5 and is likely riddled with slight misinterpretations.
I’m probably missing something you explained in your reply but if I were sitting on the edge of an event horizon and was holding a stopwatch and I was watching someone outside of the event horizon holding a stopwatch, and we synchronized our start times, I would see their stop watch go for example 10x faster - theirs would say 1 minute and mine would say 6 seconds. Wouldn’t that make my relative/actual? time much slower making my universe only 1.4 billion years old and theirs 13.7billion years old. I think I’m having trouble understanding the difference between relative and actual
Yes it is possible because it has happened. I'm not an expert, but I believe survival rates are connected more to duration than G force. If the body becomes unable to circulate blood and regulate itself for a long enough period of time, it dies.
That's exactly what happens. The human body cannot withstand more than 2-3 G for a prolonged period. Above that, the heart just can't pump blood and you die if you stay there too long. For instance, Stapp, the world record holder only withstood 46.2 Gs for a brief instant. Normally your blood weighs about 8-10% of your total body weight, so for the instant he was at 46.2 G, he weighed about 7700 lbs and his blood weighed between 616 lbs and 770 lbs.
Time moving slower inside a black hole's gravitational field would have the opposite effect from what you're thinking. Like in the movie Interstellar, when they go down to the water planet they say "one hour on this planet is equivalent to 7 years on Earth".
So any civilization within a black hole's gravity well would actually be at a huge disadvantage and have considerably less time to prepare.
I use extra virgin olive oil for marinades and salad dressing (and an olive oil spread instead of butter or margarine) and rapeseed oil (usually just labelled as vegetable oil here in the UK) for frying. The latter has a high smoke point, is lower in saturated fat compared to sunflower oil (also higher in monounsaturated and lower in polyunsaturated fats, a bit like olive oil although that has even better proportions of the two) and has better levels of Omega 3.
vegetable fats can change during the cooking process, breaking down into harmful chemicals, including aldehydes.
…
The stability of the oil is important too: some oils, like sunflower oil, are more likely to oxidise when heated – or combine with oxygen in the air – producing harmful compounds in greater quantities. A 2012 study by researchers at Spain’s University of the Basque Country reported that aldehydes can react with our hormones and enzymes.
With the issues with sunflower oil after the invasion of Ukraine the UK’s Food Standards Agency drew up a report about the substitution of other oils, which has plenty of data.
A switch away from sunflower oil should reduce levels of heart disease, following this paper:
Zatonski et al. [25] examined trends of mortality due to coronary heart disease (CHD) and fat consumption in eleven Eastern and Central European countries from 1990 until 2002. They observed that, in countries where sunflower oil remained the primary oil (such as Russia, Ukraine, Romania, and Bulgaria), the rate of CHD remained stable from 1990 onward. Meanwhile, in countries such as Poland, Czech Republic, Estonia, Latvia and Lithuania, which started to use rapeseed oil, a strong decline in CHD mortality was observed. This finding is confirmed in our study. Although both oils are rich in PUFAs, rapeseed oil contains more α-linoleic acid (ALA, C18:3), an omega-3 fatty acid with atheroprotective properties. Moreover, ALA is partly converted to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which may protect against CHD and cerebrovascular diseases [26, 27].
That article is specifically about soybean oil, but sunflower oil also has a high linoleic acid content.
I think it really depends on your total linoleic acid intake. If you’re using a variety of cooking oils, and/or different cooking methods (e.g. steaming) then it probably doesn’t matter much.
Where I think it matters is when someone is taking in a diet of mostly prepared, highly processed foods that have things like soybean oil added.
It's a bit more easily understood if you look at a space-time diagram, but essentially it kind of boils down to the speed of an object through space and the speed of an object through time are related and they must add up to 1. So if you're traveling at 50% the speed of light through space, then you're traveling at 50% the speed through time compared to an object at rest. So if you're traveling at 100% the speed of light through space, you're traveling at 0% through time, or not at all.
I’ve read about this but it kind of loses me since it’s such an abstract model of what’s going on. It treats each dimension as equal but like, time certainly seems distinct from the 3 spatial dimensions too.
I know it’s legit and a proper way of understanding it though just nitpicking since it leaves me with a sense of fuzziness like, maybe a gross oversimplification?
Granted I know it’s only meant to explain what’s happening in a predictable way not actually address the nature of these values which I guess is what I naturally lead into wondering about
I found this channel (Science Asylum) really helpful in explaining things very simply. He uses space-time diagrams in this video to explain how gravity is an emergent property of time and how the two are linked together.
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