b. We can see its effects (..the accelerated expansion rate of the universe..) but what it is or how it does what it does is totally unknown at this time. In fact, the universe started to accelerate long ago, some time in the last 10 billion years. Visible light has a shorter wavelength than ultraviolet light. Which of the following statements about energy is correct? As of 2013, the Lambda-CDM model is consistent with a series of increasingly rigorous cosmological observations, including the Planck spacecraft and the Supernova Legacy Survey. In 2004, when scientists fit the evolution of dark energy with the cosmological data, they found that the equation of state had possibly crossed the cosmological constant boundary (w = −1) from above to below. Dark Energy Is Responsible For The Acceleration Of The Universe's Expansion. [24] Dark energy is thought to be very homogeneous and not very dense, and is not known to interact through any of the fundamental forces other than gravity. 2008),[61] (Jassal et al. Eur. While the nature of dark matter has been determined, the nature of dark energy has not. The first observational evidence for its existence came from supernovae measurements, which showed that the universe does not expand at a constant rate; rather, the expansion of the universe is accelerating. Thus, unlike ordinary matter, it does not get diluted with the expansion of space. In this scenario, the Local Group would ultimately suffer heat death, just as was hypothesized for the flat, matter-dominated universe before measurements of cosmic acceleration. 0 The Amount Of Dark Energy In The Universe Is Equal To The Amount Of Dark Matter In The Universe. Lv 5. [13] Scalar fields that change in space can be difficult to distinguish from a cosmological constant because the change may be extremely slow. Inhomogeneous cosmologies, which attempt to account for the backreaction of structure formation on the metric, generally do not acknowledge any dark energy contribution to the energy density of the Universe. – Axions? ? The simplest explanation for dark energy is that it is an intrinsic, fundamental energy of space. Question: Which Statement About Dark Energy Is Correct? ", 'Accelerating universe' could be just an illusion, "Marginal evidence for cosmic acceleration from Type Ia supernovae", "The universe is expanding at an accelerating rate – or is it? Wind energy ? What's more, scientists should be able to determine which of these scenarios is correct with the experiments being planned for the Joint Dark Energy Mission (JDEM) that has been proposed by NASA and the U.S. Department of Energy. No evidence of quintessence is yet available, but it has not been ruled out either. [57] Dark energy could in principle interact not only with the rest of the dark sector, but also with ordinary matter. The first appearance of the term "dark energy" is in the article with another cosmologist and Turner's student at the time, Dragan Huterer, "Prospects for Probing the Dark Energy via Supernova Distance Measurements", which was posted to the, The first paper, using observed data, which claimed a positive Lambda term was, by Ehsan Sadri Astrophysics MSc, Azad University, Tehran, Friedmann–Lemaître–Robertson–Walker metric, Quintessence: The Search for Missing Mass in the Universe, "Cosmos Controversy: The Universe Is Expanding, but How Fast? The coincidence problem asks why the acceleration of the Universe began when it did. Which of the following statements about the lipid constituents of membranes is correct? Phantom energy? [77] A laboratory direct detection attempt failed to detect any force associated with dark energy.[46]. [81][82] The measurement of the speed of gravity in the first gravitational wave measured by non-gravitational means (GW170817) ruled out many modified gravity theories as explanations to dark energy. Element X is in group 5 and period 4 of the periodic table. Sean Carroll, Ph.D., Caltech, 2007, The Teaching Company, Albert Einstein, "Comment on Schrödinger's Note 'On a System of Solutions for the Generally Covariant Gravitational Field Equations'". Which of the following statements about dark matter and dark energy is/are true? To that end, several models have been proposed. Dark matter has only an attractive gravitational effect, while dark energy is repulsive. ? There are other, more speculative ideas about the future of the universe. In general, energy must be lost from inside a container (the container must do work on its environment) in order for the volume to increase. 53. The kinetic energy of the block is always equal to the potential energy of the spring. 2005),[62] (Wetterich. 1. [31] The Wilkinson Microwave Anisotropy Probe (WMAP) spacecraft seven-year analysis estimated a universe made up of 72.8% dark energy, 22.7% dark matter, and 4.5% ordinary matter. Some scientists think that the best evidence for quintessence would come from violations of Einstein's equivalence principle and variation of the fundamental constants in space or time. ", "New evidence shows that the key assumption made in the discovery of dark energy is in error", "Has Dark Energy Been Debunked? The "cosmological constant" is a constant term that can be added to Einstein's field equation of general relativity. d) The phosphorylation of the Na + /K + ATPase does not change its conformation. They were in for a shock: the observations showed that the expansion was speeding up. am i right? B. X can form ions with 3– charge. …, Both exceed the matter-energy equivalent of luminous matter, Dark matter has only an attractive gravitational effect, while the dark energy is repulsive in  nature. 2004),[63] (Oztas et al. Subinoy Das, in Les Houches, 2007. 1 Answer. i think that the 2nd one is correct because i no that energy is not lost when water is bpiled it is gained because of the bubbles and electrons and atoms moving around. The delocalization energy of an ester is about 10 kcal/mol, and the delocalization energy of an amide is about 18 kcal/mol. Due to the toy model nature of concordance cosmology, some experts believe[14] that a more accurate general relativistic treatment of the structures that exist on all scales[15] in the real Universe may do away with the need to invoke dark energy. Independently of its actual nature, dark energy would need to have a strong negative pressure (repulsive action), like radiation pressure in a metamaterial,[25] to explain the observed acceleration of the expansion of the universe. The other advantage is that there is a natural explanation for its origin. A. Infrared light has a shorter wavelength than ultraviolet light. The randomness of the system increases during vaporization III . The first direct evidence for dark energy came from supernova observations in 1998 of accelerated expansion in Riess et al. Some special cases of quintessence are phantom energy, in which the energy density of quintessence actually increases with time, and k-essence (short for kinetic quintessence) which has a non-standard form of kinetic energy such as a negative kinetic energy. aleahspitzley1840 is waiting for your help. This is the cosmological constant, usually represented by the Greek letter Λ (Lambda, hence Lambda-CDM model). This could, for example, treat dark energy and dark matter as different facets of the same unknown substance,[55] or postulate that cold dark matter decays into dark energy. Under this scenario, dark energy would ultimately tear apart all gravitationally bound structures, including galaxies and solar systems, and eventually overcome the electrical and nuclear forces to tear apart atoms themselves, ending the universe in a "Big Rip". In standard cosmology, there are three components of the universe: matter, radiation, and dark energy. Energy is transferred when atoms are rearranged. Which statement about energy from nuclear fusion is correct? Since it is quite rarefied and un-massive—roughly 10−27 kg/m3—it is unlikely to be detectable in laboratory experiments. [83][84][85], Astrophysicist Ethan Siegel states that, while such alternatives gain a lot of mainstream press coverage, almost all professional astrophysicists are confident that dark energy exists, and that none of the competing theories successfully explain observations to the same level of precision as standard dark energy.[86]. Thus, the current standard model of cosmology, the Lambda-CDM model, includes the cosmological constant as an essential feature. The term "dark energy", echoing Fritz Zwicky's "dark matter" from the 1930s, was coined by Michael Turner in 1998.[22]. The kinetic energy of the block is at a maximum at x = A. It has four electrons in its highest occupied energy level. Solution for Which statement is correct about waves? b. As of 2020, there are active areas of cosmology research aimed at understanding the fundamental nature of dark energy. For radiation, the decrease in energy density is greater, because an increase in spatial distance also causes a redshift.[26]. Question: Which Of The Following Statements About Dark Energy Are Correct? Energy is transferred when atoms are rearranged. (C) The kinetic energy of the block is at a minimum at x =0. Solar energy ? The phantom energy model of dark energy results in divergent expansion, which would imply that the effective force of dark energy continues growing until it dominates all other forces in the universe. To verify this theory, scientists carried out the result that shows the energy calculated through the total mass and radiation is less than the total energy. Choose one or more: Both exceed the matter-energy equivalent of luminous matter. It is sometimes called a vacuum energy because it is the energy density of empty vacuum. [29][30], Since then, these observations have been corroborated by several independent sources. e. Chemical species can have their oxidation number decreased at the cathode. Select five options. This accelerating expansion effect is sometimes labeled "gravitational repulsion". But, if quintessence is the answer, we still don't know what it is like, what it … One of the most popular models is the Chevallier–Polarski–Linder model (CPL). While moving away from the Earth (along the path from A to D) there is a component of force in the _________________ (same, opposite) direction as the motion; this causes the satellite to ___________________ (slow, Example 2.1A car travels at an average speed of 100 kmh-1what distance does it cover in 5 minutes?​, Use Newton's laws of motion to explain why it is important that baseballs and softballs each have a small acceptable range of masses.​, The bob of a simple pendulum oscillates with an amplitude of 2x10-2m and The Na + /K + ATPase uses energy to pump Na + inside the cell and K + outside. ? Distance measurements and their relation to redshift, which suggest the universe has expanded more in the last half of its life. Which statements are correct? The problem is attacked from a great variety of angles, such as modifying the prevailing theory of gravity (general relativity), attempting to pin down the properties of dark energy, and finding alternative ways to explain the observational data. D. X has 4 valence electrons. A. The proportion of hydrogen converted to energy in nuclear fusion is 7 percent. Is the universe expanding faster than the speed of light? Astrophysicists scramble to patch a hole in the universe, rewriting cosmic history in the process", "First Planck results: the Universe is still weird and interesting", https://einsteinpapers.press.princeton.edu/vol7-trans/47, "Astronomers Report Evidence of 'Dark Energy' Splitting the Universe", "Cosmology: Part III Mathematical Tripos, Cambridge University", "Wilkinson Microwave Anisotropy Probe (WMAP) three year results: implications for cosmology", Philosophical Transactions of the Royal Society A, "Big Bang's afterglow shows universe is 80 million years older than scientists first thought", "Planck reveals an almost perfect universe", "Dark Energy May Be Incompatible With String Theory", "Is Einstein's Greatest Work All Wrong – Because He Didn't Go Far Enough? Also, it is unknown if there is a metastable vacuum state in string theory with a positive cosmological constant.[50]. The cosmological constant can be formulated to be equivalent to the zero-point radiation of space i.e. While weak, such effects considered cumulatively over billions of years could become significant, creating the illusion of cosmic acceleration, and making it appear as if we live in a Hubble bubble. c. The proportion of hydrogen converted to energy in nuclear fusion is 0.7 percent. It has been argued that the dark energy hypothesis is a conventionalist hypothesis, that is, a hypothesis that adds no empirical content and hence is unfalsifiable in the sense defined by Karl Popper.[97]. It is relatively easy to measure redshift, but finding the distance to an object is more difficult. Measurements of the cosmic microwave background suggest the universe began in a hot Big Bang, from which general relativity explains its evolution and the subsequent large-scale motion. But the amount of energy in a container full of vacuum actually increases when the volume increases, because the energy is equal to ρV, where ρ is the energy density of the cosmological constant. C. The energy of infrared radiation is lower than the energy of ultraviolet radiation. Which is the best example of potential energy? The number of neutrons minus the number of electrons is zero. Much more precise measurements from WMAP in 2003–2010 have continued to support the standard model and give more accurate measurements of the key parameters. In order for it not to clump and form structure like matter, the field must be very light so that it has a large Compton wavelength. Dark Energy Is The Invisible Material That Holds Galaxies Together. What is the membrane potential of mitochondria if at 37 C pH is equal to 9 inside mitochondria, and pH=7 outside? Then, in less time than the blink of an eye, the universe expanded and increased in size by a factor of 1050[1]. 44) Which statement is CORRECT about the Law of Conservation of Energy? A study published in 2020 questioned the validity of the essential assumption that the luminosity of Type Ia supernovae does not vary with stellar population age, and suggests that dark energy may not actually exist. 3 A. The equilibrium is unstable: if the universe expands slightly, then the expansion releases vacuum energy, which causes yet more expansion. During the 1980s, most cosmological research focused on models with critical density in matter only, usually 95% cold dark matter (CDM) and 5% ordinary matter (baryons). (a) Ionization enthalpy increases for each successive electron. Explain which statement is correct: energy is lost when water is boiled or the energy used to boil water is present, but it is no longer in a usable form unless you use work or heat to make it usable. [20] and in Perlmutter et al.,[21] and the Lambda-CDM model then became the leading model. Measures of large-scale wave-patterns of mass density in the universe. Such expansion is an essential feature of most current models of the Big Bang. What happens when boundary plates collide or slide past each other? The evidence for dark energy is heavily dependent on the theory of general relativity. This happens because the physical quantity that causes matter to generate gravitational effects is the stress–energy tensor, which contains both the energy (or matter) density of a substance and its pressure and viscosity[dubious – discuss]. OHD directly tracks the expansion history of the universe by taking passively evolving early-type galaxies as “cosmic chronometers”. History of discovery and previous speculation, Implications for the fate of the universe. Answer Save. Because the Hubble parameter is decreasing with time, there can actually be cases where a galaxy that is receding from us faster than light does manage to emit a signal which reaches us eventually. Then, by exploiting the fact that baryon acoustic oscillations have left voids regularly of ≈150 Mpc diameter, surrounded by the galaxies, the voids were used as standard rulers to estimate distances to galaxies as far as 2,000 Mpc (redshift 0.6), allowing for accurate estimate of the speeds of galaxies from their redshift and distance. Expansion eventually began to slow down, allowing galaxies, star clusters, and so on, to form. Since energy and mass are related according to the equation E = mc2, Einstein's theory of general relativity predicts that this energy will have a gravitational effect. Specifically, when the volume of the universe doubles, the density of dark matter is halved, but the density of dark energy is nearly unchanged (it is exactly constant in the case of a cosmological constant). Accelerated cosmic expansion causes gravitational potential wells and hills to flatten as photons pass through them, producing cold spots and hot spots on the CMB aligned with vast supervoids and superclusters. For the shape of the universe to be flat, the mass-energy density of the universe must be equal to the critical density. The mass–energy of dark matter and ordinary (baryonic) matter contributes 26% and 5%, respectively, and other components such as neutrinos and photons contribute a very small amount. While dark energy is a force that accounts for the expanding universe, dark matter explains how groups of objects function together. Which of the following statements about dark matter and dark energy is/are true? Nearly all inflation models predict that the total (matter+energy) density of the universe should be very close to the critical density. In [S. Das, P.S. Dark Energy Exists In "empty" Space, So As The Universe Expands, The Amount Of Dark Energy Grows. 'Einstein’s 1917 Static Model of the Universe: A Centennial Review'. Work done in 2013 based on the Planck spacecraft observations of the CMB gave a more accurate estimate of 68.3% dark energy, 26.8% dark matter, and 4.9% ordinary matter.[35]. Bridget has nuclear energy. However, cosmology alone is not sufficient to effectively constrain the strength of the coupling between dark energy and baryons, so that other indirect techniques or laboratory searches have to be adopted. Therefore, it is conceivable that a modification to general relativity also eliminates the need for dark energy.

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