Ask A Scientist The Elements team answers your most pressing questions!

Q: How big is infinity, really?

A: The short answer is that infinity is unimaginably huge. List as many numbers as you can, and you will not have listed them all. Infinity is a concept, not a number, and trying to treat it like one doesn’t work. If you’ve ever taken a calculus course, then you’ll have seen it as a placeholder for getting very close to a value but never quite reaching it, as with limits taken to infinity.

The longer answer is that there are actually different sizes of infinity. Take the natural numbers, i.e. 1, 2, 3, 4, etc. There are infinitely many natural numbers. Now take all the even numbers and all the odd numbers. You might think that you’ve split infinity in half, but these groups of numbers (sets) are actually the same size as the set of all natural numbers. If you take the double of every natural number, then you have the set of all even numbers: the number of values in both sets is the same. The same can be done with the odd numbers (1).

Now for the weird part: the set of all real numbers, i.e. whole numbers, fractions, and irrational numbers (such as π), is larger than the set of integers (2). We were able to show that the set of odds, evens, and integers were all the same size by connecting every integer to every odd or even number, but that’s impossible to do with the set of all real numbers (2). Showing that is a much more complicated process, but if you’re interested, look up Georg Cantor’s Diagonal Proof to see it.

Q: What makes sunsets pretty?

A: The color of the sky which we see is the result of selective scattering of sunlight by air molecules. Visible light includes a spectrum of wavelengths, from violet (shorter wavelengths) to red (longer wavelengths). Typical air molecules are slightly closer in size to violet wavelengths, and therefore reflect and redirect them in all directions and to our eyes more effectively than for longer, redder wavelengths (3). If our eyes weren’t more sensitive to blue light than violet, we would see the clear daytime sky as violet! At sunset and sunrise, however, sunlight takes a much longer path through the atmosphere than during the middle part of the day. The light that reaches our eyes during these times of day appears reddened. A nearly infinite number of scattering events have occurred by the time sunlight reaches us, which remove the violet blue light within the spectrum and leave predominantly red wavelengths! You can imagine the same blue light you see in the sky in the middle of the day becoming increasingly red as it travels to reach somewhere further away where the sun is setting.

Q: Why is fiber optic cable faster than copper cable?

A: The two types of wiring use different methods to transmit data. Fiber optic cable uses light to send signals, while copper cable uses electricity. Light travels at 300,000 kilometers per second, much faster than electricity moving through copper, which travels at 200,000 kilometers per second (4). Fiber optic cable is designed to maximize the reflection of light as it bounces off the inside of the cable, creating total internal reflection and making it travel as fast as possible through the cable (4). Additionally, electromagnetic interference can slow the speed of electrical transmission through copper cable. Electromagnetic interference can be created by electrical systems or devices and can disrupt the electric field that travels through the copper cable as it transmits electricity (5). Fiber optic cable does not have this problem, since it doesn’t rely on an electric field, making it both faster and more consistent in speed.

Q: How do plants grow in the dark?

A: Plants, including seedlings, can grow in the dark, but not very well. When seeds are grown in the dark, or underground, they undergo skotomorphogenesis. Otherwise, plants usually undergo photomorphogenesis, which happens with light growth. Interestingly enough, the transition from skotomorphogenesis to photomorphogenesis— when the plant is introduced to light again—happens within a few minutes. These are developmental pathways for the seedlings to aid in their survival and growth. Growing in the dark is less than ideal for the seedlings, so they go through phenotypic, or morphological, changes (6). Plants without light are unable to undergo photosynthesis and therefore can’t produce vital energy. So, plants conserve energy by having smaller leaves and diverting their energy towards their roots. This is why dark grown seedlings have longer roots than those grown in light; they are attempting to reach a light source. Additionally, in the dark, chlorophyll formation is stunted, and green wavelengths are no longer absorbed, meaning pale leaves, without their familiar green color.

Q: What would happen to the Earth if the sun were a black hole?

A: There are two paths for stellar evolution, depending on the size of a star. The sun is what’s called a yellow dwarf, so it’s smaller and therefore its ultimate fate is to become something called a white dwarf (7)- incredibly dense, but not a black hole. In the process of evolution, it would expand enough to definitely engulf Mercury and Venus, possibly Earth as well. Either way, if it were as close to us as Venus, our planet would heat up beyond habitability. The only way for the scenario to occur, then, would be if the sun were swapped out for a black hole. Let’s assume that it’s the same mass as our sun. The event horizon of a black hole is essentially its surface. Within the event horizon, the velocity needed to escape being sucked in exceeds the speed of light (8) ― the point of no return. For a black hole the mass of our sun, that puts the event horizon at about 3 km (9) away from the center. For reference, the Earth is 6,371 km away from the sun. We wouldn’t get sucked into the brand new black hole at the center of our solar system, but we would also no longer have sunlight and freeze to death instead. No spaghettification, but absolutely freezing temperatures would abound.