Ask a physicist anything. (7)

[LOCO]

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The latest trio to win the Nobel Prize for Science were working on the study of exploding stars. The trio found in 1998 that the universe was expanding at a more rapid rate than anticipated, which would ultimately result in the universe becoming "more bleak".

Does this contradict, confirm or expand (pardon the pun) on the Big Bang Theory of Fr LeMaitre.

Blessings

 

[Chalnoth]

The latest trio to win the Nobel Prize for Science were working on the study of exploding stars. The trio found in 1998 that the universe was expanding at a more rapid rate than anticipated, which would ultimately result in the universe becoming "more bleak".

Does this contradict, confirm or expand (pardon the pun) on the Big Bang Theory of Fr LeMaitre.

Blessings

Well, it's a detail of the big bang theory that was not known about previously. It doesn't really change anything about the theory, but it does modify our understanding of the contents of the universe.

 

[LOCO]

Well, it's a detail of the big bang theory that was not known about previously. It doesn't really change anything about the theory, but it does modify our understanding of the contents of the universe.

Thank you for your very prompt answer.

If it was already a part of the BB Theory, they did not discover anything new.

Soooo.....Fr LeMaitre should have also been a co-winner posthumously?

 

[Chalnoth]

Thank you for your very prompt answer.

If it was already a part of the BB Theory, they did not discover anything new.

Soooo.....Fr LeMaitre should have also been a co-winner posthumously?

Nobel prizes are usually not given to those who develop theories, but instead to those who perform important experiments. Einstein's Nobel, for example, was not given for relativity, but instead for his experimental work related to the photoelectric effect.

I don't believe any of the co-developers of the FLRW metric upon which the big bang theory is based ever received a Nobel. However, the discoverers of the cosmic microwave background (which was a prediction of the big bang theory), as well as the anisotropies in this background did receive Nobel prizes.

 

[chris4243]

Wiccan Child claimed that you could crush say a cup of water into ice if given enough pressure.

It wouldn't be your normal floats-in-water ice. Normal ice is less dense than water (which is why it floats), and compressing ice would push it toward its water phase. An experiment to demonstrate this is to take an ice cube, put a string on it, and pull down on the string (or use weights). The string will sink into the ice cube as the ice under it melts due to the pressure (and the water above it refreezes because it is still cold).

But then there's some different ice, that has lower density than water (as most solids have more density than their liquid phase). If you put enough pressure on water you'll push it into one of these high-pressure ice phases.

 

[Steffenfield]

How could I make all of the electricity that goes to my house, change it's direction, and send it back to the electric company?

 

[Chalnoth]

How could I make all of the electricity that goes to my house, change it's direction, and send it back to the electric company?

Well, you can't. There is resistance in the wires that go through your house, so any electricity that enters your house will be somewhat dissipated. So the only way to prevent electrical power from being consumed in your house is to prevent the electricity from traveling into your house in the first place by disconnecting everything (or, alternatively, by flipping the main circuit breaker).

Now, you could, if you wanted, replace the wires in your home with superconducting wires (it would be incredibly expensive, and you'd need to pay huge amounts to cool them, but it could be done). However, if you then tried to allow current to pass through the superconducting wires, the low resistance would simply ensure that huge amounts of current pass through, so much so that if you don't trip any circuit breakers, you'll end up causing an electrical fire in the nearest part of the circuit that isn't superconducting. And if you did the more sensible thing and just used the superconducting wires to connect some appliance or other, then that appliance would still use up power. So no matter which way you slice it, you can't return as much power as enters your home. You can only prevent it entering in the first place.

That said, you could generate your own electricity, such as through the installation of solar panels. You would have to talk to your electricity company about this, but there is the possibility that if the solar panels generate enough, that the electrical company may end up paying you.

 

[mzungu]

How could I make all of the electricity that goes to my house, change it's direction, and send it back to the electric company?

You cannot! Buy a grid tie in inverter and some method of producing electricity like PV panels, wind generators, hydro generators etc. Make sure the utility company gives you a rate that will make selling to them cost effective and will give you a payback period of 4-5 years!

 

[Steffenfield]

Thank you mzungu and Chalnoth with your responses.

I was hoping to send my local electric company a big, middle finger and send all of the electrical junk they keep pushing on me with their inflated rates of service.

Perhaps I should just call them instead to complain.

 

[RickG]

Here's another question about ice.

Practically everyone has seen this experiment. Fill a glass with ice, and then water to the rim. As the ice melts completely the level of water at the rim stays the same and does not overflow the glass.

Now consider this. Arctic sea ice is floating ice and it is loosing mass rapidly. As this ice melts, will sea level rise, lower, or stay the same. And to keep this exercise simple, assume that any melt from glaciers is not entering the oceans.

 

[Nabobalis]

The melting of the Arctic won't increase sea levels.

 

[Chalnoth]

Here's another question about ice.

Practically everyone has seen this experiment. Fill a glass with ice, and then water to the rim. As the ice melts completely the level of water at the rim stays the same and does not overflow the glass.

This works because anything which floats upon water displaces precisely as much water as its mass. Since ice is less dense than water, it floats, and some of it remains above the water. But because the ice displaces exactly as much water as its mass, when it melts you're just left with water at the same level.

Now consider this. Arctic sea ice is floating ice and it is loosing mass rapidly. As this ice melts, will sea level rise, lower, or stay the same. And to keep this exercise simple, assume that any melt from glaciers is not entering the oceans.

Stay the same. Sea level rise will not occur because of the melting of sea ice. Rather, it occurs because of the melting of ice over land.

However, there is a secondary problem with respect to sea ice melt: sea ice tends to be very white, while the sea is very dark. This means that when there is less sea ice cover during summer months, the arctic sea tends to absorb dramatically more sunlight. This is why the Arctic sea is the one place on Earth that has warmed the most in recent decades, with some areas being as much as 10C warmer (on occasion) than they were 40 years ago. The antarctic has also seen a significant rise in temperature for similar reasons.

And this can have disastrous consequences for the ice locked on land in the adjoining areas, such as Greenland. The loss of ice in these areas has been accelerating in recent decades, with recent measurements showing much more ice loss than any models have predicted.

 

[Jazer]

The melting of the Arctic won't increase sea levels.

The melting could increase storm surges. The water is no longer trapped in the Arctic, it is now free to move around. So even if average levels remained the same the level could increase in some areas. From the wind, pull of the moon and so on.

 

[Naraoia]

Stay the same. Sea level rise will not occur because of the melting of sea ice. Rather, it occurs because of the melting of ice over land.

How big is the contribution from that compared to thermal expansion?

However, there is a secondary problem with respect to sea ice melt: sea ice tends to be very white, while the sea is very dark. This means that when there is less sea ice cover during summer months, the arctic sea tends to absorb dramatically more sunlight. This is why the Arctic sea is the one place on Earth that has warmed the most in recent decades, with some areas being as much as 10C warmer (on occasion) than they were 40 years ago. The antarctic has also seen a significant rise in temperature for similar reasons.

And to think that these same seas are swarming with very temperature-sensitive creatures...

 

[Chalnoth]

How big is the contribution from that compared to thermal expansion?

I'm not entirely sure, unfortunately. My understanding was that on very long time scales (thousands of years), thermal expansion is actually the major driver of sea level rise. However, thermal expansion takes a while because the ocean takes a long time to warm up.

And to think that these same seas are swarming with very temperature-sensitive creatures...

Yes, that too. Somewhere around half of plankton is gone now. And that should scare the you know what out of anybody.

 

[mzungu]

This works because anything which floats upon water displaces precisely as much water as its mass. Since ice is less dense than water, it floats, and some of it remains above the water. But because the ice displaces exactly as much water as its mass, when it melts you're just left with water at the same level.


Stay the same. Sea level rise will not occur because of the melting of sea ice. Rather, it occurs because of the melting of ice over land.

However, there is a secondary problem with respect to sea ice melt: sea ice tends to be very white, while the sea is very dark. This means that when there is less sea ice cover during summer months, the arctic sea tends to absorb dramatically more sunlight. This is why the Arctic sea is the one place on Earth that has warmed the most in recent decades, with some areas being as much as 10C warmer (on occasion) than they were 40 years ago. The antarctic has also seen a significant rise in temperature for similar reasons.

And this can have disastrous consequences for the ice locked on land in the adjoining areas, such as Greenland. The loss of ice in these areas has been accelerating in recent decades, with recent measurements showing much more ice loss than any models have predicted.

Also to add that sea levels rise due to the expansion of warmer oceans: [FONT=Arial, Helvetica, sans-serif][SIZE=-1]The thermal coefficient of expansion of water is 0.00021 per 1° Celsius at 20° Celsius.
Here is a very interesting article to read that also covers the expansion of water in the oceans due to temperature rise: Climate Change and Sea Level Rise
[/SIZE][/FONT]

 

[RickG]

Well, the answers about melting sea ice came along the lines I thought they would, and I'm glad to see the pick up on thermal expansion. If I had thought about it I would have taken thermal expansion out of the equation as well.

Actually, there is a slight increase. Follow the link provided below for details. What I missed as everyone here did as well is that sea ice is virtually pure water. If it were melting in pure water the scenario would be as in the glass of water. But sea water contains salt and is therefore more dense. The fresh water will dilute the sea water making it less dense and therefore take up more space.

Sea level rise due to floating ice?

 

[Chalnoth]

Well, the answers about melting sea ice came along the lines I thought they would, and I'm glad to see the pick up on thermal expansion. If I had thought about it I would have taken thermal expansion out of the equation as well.

Actually, there is a slight increase. Follow the link provided below for details. What I missed as everyone here did as well is that sea ice is virtually pure water. If it were melting in pure water the scenario would be as in the glass of water. But sea water contains salt and is therefore more dense. The fresh water will dilute the sea water making it less dense and therefore take up more space.

Sea level rise due to floating ice?

Interesting. Looks like overall it turns out to be a small effect, though.

 

[mzungu]

Sea level rise is the least of our worries. The greatest risk is the Gulf stream stopping and thus cause an Ice age to appear very quickly. Ice ages wreak havoc by trapping water as ice and the annual rainfall worldwide to decrease substantially and droughts will be the norm in any geographic zone!

Here is an interesting documentary that may help one to understand the process:

The Gulf Stream and The Next Ice Age | Watch Free Documentary Online

 

[Nabobalis]

I don't think the Gulf Stream will shut down within our lifetimes let alone our childrens.

There was a paper published a few years back saying that so far the Gulf Stream hasn't weakened so far.