The jet streams flow eastward in both hemispheres. Their directions of flow are determined by the Coriolis effect, in which high-altitude winds that are heading away from the equator veer eastward because of their angular momentum on the spinning earth.
The fax machine uses a row of optical sensors to detect dark and light spots on the original document. It scans the document one line at a time and enters the pattern of dark and light spots into a digital controller or simple computer. The controller or computer than encodes this pattern, together with enough information to correct minor transmission errors if they occur, as a series of numbers. The numbers are then sent through the telephone system in much the same way that computer information is sent through the telephone wires by a modem. The numbers becomes specific patterns of tones and volumes. While the electric currents flowing through the telephone system are meant to represent voice sounds, they can do a moderately good job of representing numbers instead. Because of various limitations on the currents that the phone wires can carry well, the fax system can only so much information each second. The receiving fax machine analyzes the tones and volumes it receives over the telephone wires and recreates the pattern of dark and light spots. It then uses one of several printing techniques to reproduce that pattern on a piece of paper. It recreates the document one line at a time.
The perception of time is different for observers who are in motion relative to one another. The issue is not how far away they, it’s how fast they are moving relative to one another. If you were to observe a person who is traveling past the earth at almost the speed of light, you would notice that their watch is running extremely slowly. It might be as though you’d have to wait one thousand years for their watch to show that a day has passed for them. Yet paradoxically, they would make the same observation about you! You would see them aging slowly and they would see you aging slowly! The resolution to this apparent paradox lies in the differences in the perceptions of space that these differences in the perceptions of time. In this short answer, I can hardly begin to resolve the paradox. I’ll simply point out that the mixing of space and time associated relativity are caused by relative motion not by relative position.
This phenomenon is the result of tiny electric sparks that occur when sucrose crystals in the Lifesaver crack as they are exposed to severe stresses. A separation of electric charge occurs between the two sides of the fracture tip and an electric discharge occurs through the air separating those two sides. The light that you see is produced by this electric discharge.
To understand how this charge separation occurs, we must look at how crystals respond to stress. Many crystalline materials are microscopically asymmetric, meaning that their molecules form orderly arrangements that aren’t entirely symmetric. To visualize such an arrangement, consider a collection of shoes: an orderly arrangement of left shoes can’t be symmetric because a left shoe isn’t its own mirror image—you can’t built a fully symmetric system out of asymmetric pieces. Like left shoes, sucrose molecules (the molecules in table sugar) are asymmetric so that a crystal of sucrose is also asymmetric.
Whenever you squeeze a crystal, exposing it to stress, its electric charges rearrange somewhat. In a symmetric crystal, this microscopic rearrangement doesn’t have any overall consequences. But in an asymmetric crystal such as sucrose, the microscopic rearrangement can produce a large overall rearrangement of electric charges and huge voltages can appear between different parts of the crystal. The most familiar such case is in the spark lighters for gas grills, where a stressed asymmetric crystal creates large sparks. In a Wint-O-Green Lifesaver, the large build-ups of charge cause small sparks that produce the light you see.
A dishwasher is really a number of simple machines that work together to clean dishes. These machines are controlled by a mechanical or electronic timer and include an electrically operated water valve, a water level sensor, one or two water pumps, a thermostat, an electric heating element, one or more rotating spray nozzles, and a fan.
The cycle begins when the timer sends electric current through a coil of wire in the water valve, making that coil magnetic and pulling the water valve into its open position. Water flows then flows from the high pressure in the water line to the atmospheric pressure in the cleaning chamber. When the water sensor detects that the dishwasher is adequately filled, it shuts off current to the valve and the valve closes.
The thermostat measures the water temperature and may delay the start of the cycle if the water is too cool. If so, it directs electric current through the heating element, where that current’s energy is converted into thermal energy and transferred to the water. When the water is hot enough, the cycle continues.
During the cleaning cycle, one or more pumps operate. They add energy to the water and increase its pressure. This high-pressure water flows slowly to the rotating nozzles and then accelerates to high speeds as it enters the narrow openings and sprays out into the low-pressure cleaning chamber. As the high-speed water collides with the dishes and slows down, its pressure rises again and begins to exert substantial forces on the food particles. The food particles are pushed off the dishes and fall into the bottom of the dishwasher. Soap added to the cleaning water forms tiny spherical objects called micelles that trap and carry away fats that would otherwise not mix with water. At the end of the cycle, the water, food particles, and fat-filled soap micelles are pumped down the drain.
The cleaning cycle may repeat with fresh water and is then followed by a rinse. A soap-like surfactant may be added to the rinse water to lower its surface tension and prevent it from beading up on the dishes. When the pumps have removed the last of the rinse water, a fan begins to blow air over the dishes. The heating element may heat this air to assist evaporation. The water molecules leave the surfaces of the dishes and become gaseous water vapor. The dishes are left clean and dry.
It doesn’t. When you dial a rotary phone, it briefly hangs itself up one time for every number on the dial. Thus if you dial a “5”, it hangs itself up briefly 5 times. In fact, you can dial the phone by tapping the switchhook briefly one time for every number. For example, if you want to dial a “5”, tap the switchhook (hang up the phone) briefly 5 times very quickly. It takes some skill, but you can “dial” just fine without ever touching the dial. It used to be that people installed key locks on the rotary dial to prevent unauthorized use of the telephone. Unfortunately, this action didn’t prevent someone with a nimble hand from dialing with the switchhook.
This seemingly simple question has a surprisingly complicated answer. You might expect that if the earth and one of these distant galaxies had been very near one another at the creation of the universe and had both been moving away from one another at almost the speed of light, that after 15 billion years each would have moved almost 15 billion light years in opposite directions and would thus be separated by almost 30 billion light years. That’s not the case. That simple view ignores the important effects of special relativity on rapidly moving objects.
To understand these effects, suppose that there was an observer who was stationary at the creation and watched the earth and galaxy head off in opposite directions at almost the speed of light. From that observer’s perspective, the two objects are heading away from one another at almost twice the speed of light. After 15 billion years, this observer sees the galaxy as almost 30 billion light years away from the earth.
Now suppose that there was another observer who was on the earth at the creation. From this person’s perspective, the galaxy recedes from the earth at almost the speed of light, but no more. Nothing can move faster than speed of light! After 15 billion years, this observer sees galaxy as almost 15 billion light years away from the earth.
These two observations don’t seem to agree. The problem lies in how the two observers perceive time and space. According to special relativity, observers who are moving relative to one another don’t perceive time and space in the same way. Their perceptions will be so different that they will not even agree about just when 15 billion years has passed.
With this long introduction, here is the answer to your question: no distant galaxy in the observable universe can ever be farther from us than the distance light has traveled since the creation of the universe. Since that creation was about 15 billion years ago, the most distant possible galaxy is almost 15 billion light years away.
Because there is no preferred reference frame for the universe, we can only talk about the earth’s speed in reference to other objects. For example, the earth is moving at about 5 kilometers per second relative to the sun and about 30,000 kilometers per second relative to the center of the galaxy. These speeds do affect our perceptions of time, so that times passes at a different rate for us than for someone closer to the sun or to the galactic center. However, gravitational wells also affect the perception of time, so that the effects are complicated. The earth is also receding extremely rapidly from objects at the far side of the universe; so fast that time passage is dramatically affected. Those distant objects appear to be aging very slowly and their light is shifted substantially toward the red.
Your telephone performs all of its functions using only those 2 wires. The 2 extra wires are virtually never used by a single-line telephone. The only exception that I’m aware of is the old “Princess Telephone,” which had a special light powered by the extra pair of wires. In most telephones, even the power for the lighted keys comes from the 2 main wires. While the telephone is off the hook, the telephone company sends a constant DC current through those two wires. This current powers the telephone’s electronics and its lights. When you talk, the microphone causes the telephone’s electric impedance to fluctuate up and down and this variation causes sound to be reproduced in your friend’s earpiece. Pressing the dialing buttons causes similar fluctuations in impedance and the telephone company uses these tones to make the proper connections. When the telephone company rings your telephone, they send a higher voltage AC current through the two wires and the telephone’s bell rings.
The sensor has two lenses: one that emits a beam of infrared light and the other that looks for a reflection of that light. As long as there is nothing beneath the faucet, there is very little infrared light reflected back toward the sensor and the sensor prevents any water from flowing out of the faucet. But when you hold your hands under the faucet, the infrared light reflects from your hands and some of it returns to the sensor. The sensor detects this light and opens an electronic valve to permit water to flow out of the faucet. The lenses are aimed so that only objects under the faucet itself will reflect the infrared light back toward the lens. A more distance object may reflect some of the infrared light, but the light won’t pass through the sensor at the proper angle and won’t be detected.