Yahoo! UK & Ireland Answers blog

Photo by Redvers

Answers is a goldmine of information, a maze of questions and curiosities, experiences and wonder. Navigating  it can be tricky though, especially beyond the usual categories. So in the first of a new type of blog post, we attempt to migrate meaningfully through the billion pieces of content we have on the site worldwide, finding connections as we go. We start our journey with one simple, high quality question…

Q: How do you read railway signals?

A:  “There are a bunch of them. But understanding some terminology will help you in your research. The first one is “aspect.” The aspect is the appearance of a signal that displays information to an approaching train. These are the different colours block signals display. Most commonly seen are red, green, yellow, yellow over yellow and flashing yellow. There are many other combinations. The next term is…” Read the full answer here>

Photo by Brostad

Railways are a fascinating subject, one that draws us back into history and how so many nations industrialised. Stephenson’s Rocket is well known as the first steam engine to go beyond the experimental phase and from there the mode of transport blossomed. It began to expand over the globe, leaving Answers users to ask…

Q: What is the longest railway route in the world?

A: “The longest railway in the world is considered to be the Trans-Siberian railroad (TSr). Its entire length is 9259 km (5753 miles) and goes from Moscow (western Russia, and capital) to Vladivostok, far in the East, a port on the Pacific. Total journey time is usually one week. The TSr branches off to make the Trans-Mongolian Railroad (Moscow to Beijing via Ulaan-Baatar [capital of Mongolia])”

Lake Bikal photo by World Resources Institute Staff

Over 9000km is a pretty serious journey and at least one Answers user, Our Man In Bananas, has taken it.

“Two years ago I took the Trans-Siberian Express from Moscow to Irkutsk then Lake Baikal, where I jumped on the Trans-Mongolian Express to Beijing . I’d recommend you try and do at least 3 stopovers (or 4 if possible), and believe me, Lake Baikal is a must.”

“At all costs, make sure you take the Circum-Baikal train, which is known as the Tzars Golden Buckle, because building in bankrupted Russia . I hope that gets you started, it’s a magnificent journey that you will never forget and the cheapest long-distance train in the world too…”

See some more, pretty incredible images of Lake Bikal on Flickr here.

Naturally the Trans-Siberian railway passes through Siberia, a notoriously cold place, in fact the coldest inhabited place in earth. According to Irish Joe, the Verkhoyansk Mountains of northeast Siberia have winter temperatures fall to −71°C (−96°F). Now that’s cold. But what is the coldest part of the earth? Not the spot on the surface that’s coldest, but the coolest overall layer of the earth itself. Star B wanted to know, and thankfully Bella was on hand to help.

Q: What layer of the planet earth is the coldest?

“The crust or lithosphere is the coolest layer by far. It is what we live on. It is in the vicinity of 0 degrees C (varying with depth and location). The mantle is about 1,700 miles (2,750 km) thick. The mantle gets warmer with depth; the top of the mantle is about 1,600° F (870° C); towards the bottom of the mantle, the temperature is about 4,000-6,700° F (2,200-3,700° C).

The inner core may have a temperature up to about 13,000°F (7,200°C = 7,500 K), which is hotter than the surface of the Sun. The inner core (which has a radius of about 750 miles (1,228 km) is solid. The outer core is in a liquid state and is about 1,400 miles (2,260 km) thick.”

All this talk about 7,200 °C core brings imagery of lava and molten rock, like these shots from the Volcano group on Fickr. But Garrett wonders…

Q: Why don’t we harness their power to solve another tricky energy power problem: nuclear waste?

“Dumping into a volcano, and injecting into the mantle are two entirely different things. If we could manage to bore deep enough to get to the mantle, there may be something to your idea. We would want to do that far from potential sources of eruption. Of course, we don’t come anywhere close to drilling that deeply. If we dropped that stuff into a volcano and the volcano erupted, that would be really bad – shot up into the air etc. The usual idea is to put that stuff somewhere very geologically stable so that there is the smallest chance possible that an earthquake or eruption will spread that nasty, dangerous stuff around.”

Image by Floodkoff

Richard has a great answer too. Perhaps it wasn’t such a great idea after all, and reminds us of the challenges of nuclear power and all the waste and containment issues it generates.  JST Max is of similar mind, asking…

Q: What is clean energy?

“”Clean”, or renewable, energy sources are energy sources that are continuously replenished by natural processes. They are flows of energy (from the Sun or the planet’s hot core) while fossil and nuclear fuels are to great extent stocks of energy (stored, accumulated energy).

According to the World Energy Assessment report (2004) “Renewable energy sources generally depend on energy flows through the Earth’s ecosystem from the insolation of the sun and the geothermal energy of the Earth”.

More info here:

Broadly, the following are renewable (clean) energy sources:

• Biomass energy (plant growth driven by solar radiation)
• Wind energy (moving air masses driven by solar energy)
• Direct use of solar energy (as for heating and electricity production).
• Hydropower
• Marine energy (such as wave energy, marine current energy, and energy from tidal barrages)
• Geothermal energy (from heat stored in rock by the natural heat flow of the Earth)

If you ask me, if the current reliance on fossil fuels and nuclear can be substituted by use of renewable energy listed above, then my answer would be: “Yes, of course!” However, to be realistic here, this process will require decades to make such a transition and a lot of political and individual will and commitment.”

And if you’re talking about green energy sources and being better for our planet, then cutting down carbon emissions comes to mind, not least through greener transport. Which brings us full circle back to W23 and his question about railways again…